No announcement yet.

Vorshlag C4 Corvette TT Build: Project DANGER ZONE

  • Filter
  • Time
  • Show
Clear All
new posts

  • Vorshlag C4 Corvette TT Build: Project DANGER ZONE

    Project Introduction, Dec 19th, 2014: Welcome to Vorshlag's latest crazy project build thread. Many of you know how we have documented our various project builds on the forums over the past 12 years and this will be another fun one. I will (soon) be cross-posting this on a number of forums, listed below. Pick your favorite, subscribe, and feel free to join in the conversation! If you've never seen my build threads before, there are links buried throughout (usually in bold) as well as LOTS of pictures. Click on any picture posted and it usually goes to a larger resolution version. I will embed videos in here, too.

    Before we get started I have to admit that this is just an introductory, background laying TEASER post. In it I will describe in basic terms what we are doing, and why, but we ARE NOT revealing what this new TT build car is until AFTER our first time trial competition event (NASA at MSR Houston Jan 17-18, 2015). Why? Everyone likes surprises, and I want to spring this on our competitors before they pitch a fit and leave the class, hehehe! This car will be built to run in a NASA Time Trial "letter class" (something from TTB to TTF) as well as SCCA Club Trials (when the two clubs' events don't overlap!). We might sneak it into a few other series and classes, if it looks like a good fit.

    Who Are These Vorshlag Guys?

    Some of you know Vorshlag (primarily a suspension parts manufacturing and supply company + street/competition prep shop) from our various online build threads, like our 2011 Mustang GT, shown above. We purchased this "test mule" to use for parts development, and with it we tested with 3 brands of shocks (AST, Moton and MCS), all with custom valving. We developed our second revision of the S197 camber plate set-up, helped Whiteline develop and test lots of parts, developed an 18x10" D-Force wheel for the S197 chassis, and tested and race proved Forgestar wheels, among other items.

    We tested these things by campaigning it in various racing groups over the past past 4 years (GTA, SCCA, NASA, USCA, Optima, Goodguys) and it was extremely competitive in the last 2 seasons in NASA's TT3 class, with dozens of wins and setting 13 NASA class track records. We also won with this car in Optima/USCA, SCCA Club Trials, Goodguys autocrossing, and more. All of the development on this car has been shared on this Project Build Thread, but that car is currently for sale (here) and off limits to me on a race track from now on. We kind of went overboard on the custom fabrication and suspension work with that build, so somebody is going to get a smokin' deal when they buy it.

    This Mustang was an example of Winning at All Costs. We used the best (and most expensive) suspension, high end aero parts, lots of custom body mods, and we ran on brand new "sticker" sets of Hoosier A6 tires ($1700 worth per weekend) at each event to guarantee success. Maybe we over did it... we set every TT3 track record for 2 years on the NASA Texas calendar and in 2014 had win margins over 2nd place by 5-7 seconds on most race days. Overkill costs extra. This DANGER ZONE project will be more about Winning with Low Costs, spending just enough to get that win, without massive overkill modifications or needless expenses. The inherent nature of the TT lettered classes limits our ability to go hog wild with spending or mods, too.

    Our TT3 Mustang was a big brawler - we ran it HEAVY, with the biggest tires Hoosier made, and with huge aero

    We learned a lot of valuable lessons with the TT3 build, with breakthroughs and mistakes, and shared them all publicly. While we had generally excellent results the last 2 years, the first 2 years of competition were a bust (poor planning on my part put it into the wrong series & wrong class), and even in 2014 I made a critical error that caused a high speed off. That little shunt at Road Atlanta caused some injuries to my back, but barely hurt the car or the splitter - this car is a tank! I am not keen to repeat those mistakes - so we will use all test data we can get and over-do the safety aspects on this car (spending far more on safety upgrades than are required in Time Trial - so I'm not counting that in the "race prep" budget). That TT3 car progressed greatly the last 2 years, winning 13 of 15 NASA TT events in 2013 and all of the TT events we entered in 2014, while securing the Regional TT3 championships both years by huge margins (with the maximum possible 800 class points). We relearned the importance of tires (width and compound) in TT, the value of proper testing, where to spend money on suspension, and of course we played with a lot of aero.

    At Vorshlag, when we purchase "shop car" it is to develop new parts + to go prove those parts in competition. We usually only keep a car for one or two years, jumping around from different makes and models that have ranged from BMWs, Mitsubishis, Subarus, Mazdas, Chevys, Fords and more. Running the same red Mustang four seasons in a row has somehow made us into a "Mustang shop" in many people's eyes. But Vorshlag is much more than that - we make suspension products for over 24 different makes/models and prepare and build race-oriented cars for many motorsports venues, including autocross, HPDE, TT, Club Racing, Pikes Peak, drag race, rallycross, and even top speed competitions.

    This pair of Subarus we have worked on aren't track cars. Left one is made for running Bonneville, the other for Pikes Peak

    We hope this new build will show some of the variety of cars we work on, across all budgets, and show off some of the fabrication and race prep skills our crew excels at. Of course we are known for LS1 swaps into BMWs (E30, E36, E46, Z3 - see below) and we have Alpha Builds (development projects for future kits) for the Miata NB chassis and Scion FR-S/Subaru BRZ as well. We have sold over 120 V8 swap kits since 2007 and we keep picking up new platforms to add big aluminum V8s to. Sadly, project DANGER ZONE won't be getting LS1 V8 powered swap, but it will make good power for it's class.

    A lot of people that see us at the track or read our build thread think "These Vorshlag guys spend a lot of money!", but the reality is we build our cars to run on a tighter budget than you might think. How did we stay on sticker sets of Hoosier A6s in 2013 and 2014? We won all of them, except for 1 set purchased at the beginning of the 2013 season. Our service shop also has experienced mechanics and fabricators who do all of the work on our cars between paying customer work - so we have the manpower, tools and skills, but not always the big bags of cash. We kept the engine bone stock on our TT3 car because it was easier for us to do suspension and aero mods than "purchasing horsepower" (we don't build or tune motors here). We also have two guys in the front office that are crew chiefs on outside race teams, and everyone that works here is a racer with regular motorsports experience, track side and/or behind the wheel. So a lot of times we build the things that might seem "expensive" to others, but are really just hand built items that come from hard work and experience - which can often be worth more than just throwing money at a race car.

    We have done some very low budget builds, too. In late 2009 we wanted to try our hand at a budget-restricted magazine shootout, so we jumped into the Grassroots Motorsports sponsored $20XX Challenge. This is an annual 2-day competition event with 3 differing categories: autocross, drag race, and concours. You have roughly two grand to spend on the car and parts, plus a rigid set of rules to go by. With an all-volunteer crew (15 people helped put in 1200+ man hours!) we built a BMW E30 in my home garage with a truck LS-series V8 and ran it in the the GRM $2010 Challenge (as in: we spent less than $2010). We did fairly well that first year, learned a LOT by going to that event, recognized what mattered most by watching the winners, and came back in 2011 and won the whole thing. Lots of people fell in love with that car - whether it was the home built wide body, the nasty little V8 under hood, the BMW Art Car inspired graphics for 2011, or the extensive custom fabrication work done throughout the car to keep the parts budget low.

    I also ran our little GRM E30 in NASA TTU class (where it fit with the power to weight ratio it ended up with) and had a blast there as well. It was actually a better track car than an autocross car, funny enough. We cleaned it up, added a splitter, added some good looking 18x11" CCW wheels and sold that car for $18 grand... so sometimes your budget builds DO pay off after all!

    Our very first NASA TT car was the TTU BMW E36 LS1 shown above, and it set an overall TT track record in its debut event way back in 2008. After that car left our stable we had a couple of other autocross cars that we ran briefly in TT lettered classes as well. My blue 2001 BMW E46 330 coupe (below left) was built initially around SCCA's DSP autocross class, flared with big 285s under all four corners, but it proved to be a MUCH better track car in TTD. It was run exactly one time and set a TTD record in the process. Same went for our STU autocross prepped 1997 BMW M3, which set a TTC record in one outing without any considerations made for track use.

    These two Bimmers were initially built as SCCA autocross cars but ran briefly - and won - in NASA TT lettered classes

    Before This Our 2015 Race Season Looked... Bleak!

    After the last two successful seasons running our Mustang in NASA TT3 and a couple of other series, this car was tidied up for SEMA with new flares, new paint, and new aero. We ran it at the Optima Challenge after SEMA as well, then when we came back home in November mid it went up for sale. The car looks so perfect right now that nobody here will let me take it out on track. They think I'll bang up the bodywork or paint... and with as wild as I drive, they are probably right. It now sits to await its new buyer, untouched and undriven.

    A major shop upgrade + new machines and equipment + extended SEMA/Optima trip all cost a lot of money

    We just moved into a new shop that is twice as big as our old place, and did construction here for 6 weeks before we moved. The move happened 2 days before we went to SEMA, which was a 10 day trip for almost everyone here at Vorshlag. The pair of CNC machines arrived a month later. So needless to say, a lot of money was spent on the pre-SEMA car work, the move, construction and equipment of late. My "its a done deal" buyer for the Mustang fell through right before SEMA, too. All of that combined put a series dent in my personal 2015 racing budget!

    There's a whole program of cars I was hoping to kick off with a shop built BMW E46 with a BIG nasty LS1 motor planned, and I've got 3 more chassis sitting in my home shop along with this E46, awaiting this turn-key race car program to start. But getting the drivetrain parts and wheels alone is going to take about $20K in cash, which seems to be missing at the moment, heh. So this project is delayed a bit while we get our CNC machines up and running and finish the construction at the new shop, so that meant no Vorshlag team car would be on track for at least 6 months. Sucks.

    In Texas we race dang near year round. We did some track testing with the new S550 Mustang as recently as this December and there are NASA and SCCA road course events we need to hit in January and February, so there's no "off season" to complete any big build. Even if we kicked off the E46 build TODAY it wouldn't be on track until May or June. That's the majority of our Texas race season, and NASA Nationals West is in August. Long story short: We're out of time, and need to make a quick, low budget race car to be able to make the 2015 NASA race season.

    continued below
    Last edited by Fair!; 04-23-2019, 02:01 PM.
    Terry Fair -
    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

  • #2
    Re: Vorshlag Budget TT Build: Project DANGER ZONE

    continued from above

    Well as luck would have it, something came up and I am picking up a semi-finished race car this weekend. Until we fix a few things, and do a track test, I'm keeping "identities withheld to protect the innocent", so the make and model of the car are under wraps. It will be prepped and stored off site in a secret skunkworks facility...

    NASA Time Trial Classing - A Brief Summary

    This next bit might be confusing, but I'll be quick. So NASA Time Trial series rules are nearly identical to the Super Touring (ST) wheel to wheel club racing ruleset, without a lot of the safety requirements. Those two series' subsets of classes have a lot of common competition rules but with two distinctly different main philosophies. The "Lettered Classes" (TTB/TTC/TTD/TTE/TTF) are set-up where every car model gets assigned a "base class" then you get 19 points per class to use for "mods", which could be added tire width, aftermarket springs, aero tricks, various tire compounds have differing points values, motor upgrades, etc. If you modify the car beyond your allocated 19 points the car bumps up a class (like from TTD to TTC), and you get another 19 points to use in that class.

    NASA Time Trial Rules:

    We bought the Vorshlag shop TTB, TTE and TTU cars to a NASA event once and ran them all. That was a hectic day...

    These classes also each have their own minimum weight to power ratio that you cannot exceed even if your points expenditure is on lowering weight or horsepower additions, and each base classing includes a "base weight" you start with. If you want to run lighter than the base weight, it costs you points. If you want to run more tire than the base class tire, points. Some base classing also come with either a 7 or 14 point penalty, too (one star or two stars).

    Each competition letter class has an assigned a minimum “Adjusted Weight/Power Ratio”. Regardless of how many points a car has, or which base class it begins in, it may not exceed the minimum “Adjusted Weight/Power Ratio” for its competition class. We will have to play with weights or power levels to stick with the limit for the class we're choosing, which could be one of the following:
    • TTB 10.50:1 (10.5 pounds per dyno measured wheel horsepower)
    • TTC 12.00:1
    • TTD 14.25:1
    • TTE 16.50:1
    • TTF 19.50:1

    Each letter class is also has an assigned "base tire width", regardless of what the OEM tire is. That list is below, as is small sample of typical base class listings.

    TTB: 265mm, TTC: 255mm, TTD: 245mm, TTE: 235mm, TTF: 215mm, TTG: 195mm, TTH: 175mm
    • BMW 330 ('01-'06) (factory 225hp models)... base class TTE... minimum weight 3285 lbs... Base tire is 235mm, power to weight limit is 16.5:1. You have 19 to play with before bumping up a class and could dyno a maximum 199 whp at the minimum weight shown (with driver).
    • Ford Mustang GT ('05-'06)... base class TTD**... minimum weight 3450 lbs... Base tire 245mm. power to weight limit is 14.25:1. Two stars (-14 penalty) means you only have 5 points to play with before bumping up a class and could dyno a maximum 242 whp running at the minimum weight shown (with driver).
    • Mazda RX-8 (R3 model) ('09-'11) ... base class TTC... minimum weight 3045 lbs... Base tire 255mm, power to weight limit is 12:1. You have 19 to play with before bumping up a class and could dyno a maximum 253 whp at the minimum weight shown (with driver).

    The inherently faster and less rules encumbered "Numbered classes" (TT1/TT2/TT3) are different and modifications are almost completely "free" and your power to weight ratio is what matters. Some cars are so fast in stock form they get a base classing in TT1/2/3. There are "modifiers" to that ratio if you run non-DOT racing slicks, sequential transmissions, AWD, and other major parts or changes like that. TT3 is unique in that any non-base trim level OEM aero mods cost you a big 0.5 modifier on your power to weight (we took that in our Mustang build, for example), but aero mods are free in TT1 and TT2. TTU is the "Unlimited" class for NASA TT as well - you can run it as light and as powerful as you want, so long as it meets safety rules and has bodywork over the wheels (NASA eschews all open wheeled race cars).

    That was a brief summary only, and I hope that made sense. We wrote this basic primer on NASA TT back in 2008, and of course the TT rules are linked above.

    We like making track cars fly - using non-stock aero tricks helps in Numbered Classes, but costs "lots of points" in Lettered Classes

    We weighed the options for our TT3 and took the aero penalty (running a massive wing out back and splitter/ducted hood up front), maxed out the power to weight ratio (running at 3802 pounds to keep power at 433 whp peak, off of an adjusted 8.8:1 pounds per horsepower ratio), and ran the biggest, stickiest tires made by Hoosier (335F/345R Hoosier A6). On that car we realized early on that the softer tire allowed us to get our fastest lap in the first two laps, before the front of the field tends to catch the back markers, which usually ensured a traffic free lap. That matters. We also noted the wider we went on tires (we started at 265, then went to 275, 305, 315, 335 and 345) the faster the car got. The added areo helped the car in high speed corners, of course, but also seemed to make braking better as well. We hope to apply some of this experience on our new TT car here, which is almost old enough to qualify as a vintage car, but spend less than 1/10th the budget. Will it work?? Are we delusional or genius?? You shall soon see...

    Maximum Effect from Minimal Investment

    This time we're not starting with a $40,000 brand new car, we're starting with an aging a 24 year old... well.... beater. This car was purchased by the previous owner for $3000, and then he sold the interior bits and some other discarded parts and recouped $1000 of that, so it was s cheap starting point. He then semi-prepped it for TT use but got busy with other projects and he suddenly wanted it gone - so it will soon came to my home shop to knock out the repairs and finish race preparations.

    It happens to be "base classed" particularly well, and once people who know TT classes see where it ends up they might cry foul - but is has been classed there for many years and I've been waiting for someone to build one. We will document all of modifications we do openly, show all testing performed looking for every ounce of speed, and post any race wins or losses along the way. Like we tend to do with all of our builds, we will be pouring over the rules looking for the optimum modifications allowed, and with several 25+ year veterans of amateur and pro racing working at Vorshlag, we know how read rules and seek out the most advantages possible.

    "Rulebook Research" and bench racing is all part of the fun of building a new race car, for us, and we've probably spent over 25 hours so far just looking at the "free" mods. We have run countless permutations allocating every point in the class (it isn't going to jump up a class), and going over every tire width/compound option, but there are still many unknowns in this build. Will an aero trick worth two points be worth more than a cat-back exhaust? We'll test that. What about this +10 point compound narrow tire vs a much wider +2 point tire? Testing it. Can it meet the power-to-weight limit? We'll dyno test the car early and often through the build.

    Of course it wouldn't be a Vorshlag build without digital scale pics; we will weigh EVERYTHING we touch. A lot of the interior has already been removed (its 400 pounds under the "base weight", so it will be getting some serious ballast added along with my 200 pound body) and nearly 50 pounds of drivetrain mass has been removed (100% legally), so the bone stock OEM motor is pretty "peppy". Look forward to lots of tech in this build thread which you might enjoy reading - or enjoy applying to your own track build.

    If You're Not First You're Last

    That Ricky Bobby logic above is going to apply here. As with our most recent TT build, pushing the limits but keeping it 100% legal is our goal for this project, so we won't be satisfied with anything other than a dominant performance and squeaky clean results in after-race inspections. We want to set ALL of the track records, win ALL of the trophies, get ALL of the points, and take home ALL of the contingency tires ... we basically want to swoop into a class we've not run before, act like a school yard bully and take all of their lunch money!

    We will be adding a roll cage and fire system, but that's not going to be shown as part of the TT "race prep budget"

    Total build budget for this build for the 2015 season we are shooting for is $7500, all-in with initial purchase price + parts. That's not a lot of money for what we think we can pull off with this car, and what we predict the lap times will be (shooting for 6-8 seconds a lap slower than our TT3 records). We will continually be upgrading the car all season, as shop time and budget permits, and it will have proper safety gear (full cage, fire system, nets) very quickly. Who knows - it might even become legal for the mating ST class?

    Tune in next time to see if we managed to win our first TT race or failed in epic fashion - either way, it will be entertaining! I will go back after the January NASA race coverage and show the initial 4 week build-up, any pre-race testing, and all of that. I also reserve the right to delete this thread and disavow all knowledge of it if the results are dismal.

    What's Next + Vorshlag 2015 Race Schedule

    These are the Time Trial and other competition events we want to enter with this car in 2015:
    • January 17-18 - NASA @ MSR-Houston Clockwise
    • January 17-18 - SCCA Club Trials @ MSR-Cresson (GRR! Why do they book the same weekends!?!)
    • February 14-15 - SCCA Club Trials @ TWS
    • March 14-15 - NASA @ MSR-Cresson
    • March 22 - Goodguys AAS at TMS (200 treadwear)
    • March 28-29 - USCA @ TMS (200 treadwear)
    • April 25-26 - NASA @ TWS
    • June 13-14 - NASA @ Hallett Summer Shootout
    • July 31-Aug 2 - NASA @ Laguna Seca - Western States Championships
    • September 4-6 - NASA @ VIR - Eastern States Championships
    • September 26-27 - NASA @ MSR-Houston Counter-Clockwise
    • October 17-18 - NASA @ "TBA" (???)
    • November - NASA @ "TBA" (probably ECR)

    The main goal is to hit all of the NASA Texas events, and while the Laguna Seca "NASA Nationals West" event isn't that likely for us, "NASA Nationals East" at VIR might be in the cards. Right now we have only FOUR weeks until our first NASA race (we will skip SCCA for NASA, you double-booking dingbats), so its going to be a thrash to get it prepped for track use in less than 30 days! Our shop is very booked with suspension and race prep work, so I will work on it after hours if need be to get it done. Sleep is for the dead!

    Our fab shop just took this street car and turned it into an ST3 prepped race car - cage, wiring, fire systems, aero - in 6 weeks

    This is going to a gutted/stripped car with NO compromises for street use at all, which we believe gives us the best chance for success. Daily driven cars haven't won many (any?) TT national championships with NASA in a while. This car has some great prep by the previous owner but it still needs some basic upgrades before it is fully track ready. We need to swap out the radiator for a racing-duty version, add an oil cooler, build in some major front brake ducting, install a proper racing seat (have one sitting in the lobby that I will steal), bolt in some harnesses and wrap them around a 4-point roll bar (initially; cage will be done hopefully by the February event). It also needs tires, a new windshield and a few other small repairs. Again, this is a CHEAP car to start with but when we're done its going to be embarrassingly quick on track. Cheap and Quick!

    My final reason for building and racing this car in 2015 is - I'm a degenerate racing junkie, and I was clawing my eyes out thinking I was going to miss the next race season. Sure, I'm bummed that we cannot have the TT1 car built in time to run with NASA this year, so this was my only possible racing option. But I figured that running in a quarter century old beater has to be more fun than NOT racing anything at all, right?

    What's in a Name?

    We're going to be focusing exclusively on The Things That Matter, so there will be very little time spent on cosmetic improvements or other frivolous upgrades. But of course we do have a vinyl plotter, and a big part of running this car is MARKETING for Vorshlag, so we will throw some simple graphics on the car based loosely on the Martini stripes on the Porsche 918 shown below (substituted with Vorshlag's Red/Black/Silver colors). We're trying to show that we can make anything fast and win, even aging 1980s era cars that have been mostly forgotten.

    “Something, something, danger zone! I know. I’m not even trying anymore.” - Sterling Archer

    We've come up with a project name (gotta call it something other than "Broke Ass, Last Minute Backup Racing Plan") which has some obscure references to the 1980s, when this particular car was designed. After about 3 minutes of brainstorming we picked Project (DANGER ZONE), which might make more sense when we get this thing on track (there is usually an inherent "Zone of Danger" surrounding me on track, especially in nearby grass areas). We tossed around some ideas to get there, like: the fact that this car designed in the 1980s, it may or may not have been on a cheesy 80's detective show called Miami Vice, which led us to the cars featured in Grand Theft:Auto Vice City, which inevitably led us to the last season of ARCHER season 5: Vice. That's only one missing step to tie into Kevin Bacon, I think. And who doesn't like Archer? Think of all the quotes I can use in my write-ups! This car would fit in well that TV series, if we added an in-dash mini-bar.

    ...and THAT'S how you get ants...

    Other than those obscure hints, I'm keeping my lips sealed. The car will be built at a "secret location" (Dick Cheney's basement), so no matter what you think see in the Vorshlag shop, I won't reveal this dirty little secret until after Jan 17th. I will be posting more clues on the Vorshlag Facebook page, so keep an eye out there.

    Until next time,
    Last edited by Fair!; 08-05-2015, 05:50 PM.
    Terry Fair -
    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


    • #3
      Re: Vorshlag Budget TT Build: Project DANGER ZONE



      • #4
        Re: Vorshlag Budget TT Build: Project DANGER ZONE

        Project Update for December 29th, 2014: This is an unexpected update - I'm going to break "radio silence" early because too many of you have guessed the car we are building before it's first race. Many of the guesses were hilarious and infinitely entertaining, and some of them were pretty good ideas for TT builds. More importantly this little project got some engagement and feedback. I'm always looking for feedback and comments, in case you have a better idea or way to do something, so keep it up! Now let's get to the answers to "The What and the Why" in this update.

        Lucky guesses and True Detectives

        Here were the initial clues I put in the first post, then some follow up clues on social media and various replies to questions and guesses on the forums. The clues became more specific as more folks chimed in with better ideas and guesses. If they gave their reasoning in their replies I would often answer yes or no, which led to more clues over the past few weeks.
        • It's not a Mustang
        • It's nearly 25 years old (so roughly a 1991 or 1992 model)
        • It's a chassis designed in the 1980s + something related to Miami Vice?
        • It does not have an LSx V8 in it, but it will be run with the factory installed engine
        • Worth about $3000 nowadays (in poor condition!), when purchased right
        • Not a turbo nor a 4 cylinder, and definitely not Front Wheel Drive
        • I stated that we would be racing on a tire 30mm smaller than the OEM size
        • I drove through Madisonville, Texas on the way to pick up the car from Dallas (hence a lot of guesses that it was in Houston)
        • After picking the car up I said it had a flywheel/clutch 50 pounds lighter than stock, and spun the tires through the 1st three gears
        • I hinted that I had possibly owned one of these cars before, and towards the end I said it was domestically produced
        • Lastly I said I worked "under the bonnet" one day last week, but then admitted not everyone calls it that but it was "more than just a hood"

        All of these things were 100% true. The "Danger Zone" name was the only red herring, heh. That last clue was what triggered an avalanche of correct guesses. Jason Newman was the first to guess correctly - and he knew he was right a week before anyone else - with only about half the clues. That guess gets him a free Vorshlag T-shirt! Several others guessed "C4" along the way as well.

        My Past Was Also A Hint

        It helped that Jason knew more about me than most - he was a racing friend from college, when I raced in and helped run the largest collegiate sports car club in the country, the Texas A&M Sports Car Club. This was a club with over 150 members when I was there and we had one of the best autocross sites in the country - an old air force base that the school owned (Riverside Annex).

        Left: My 1994 LT1 6-spd Corvette Z07. Right: One of three V8 1992 Camaro 1LE/B4Cs (ex-pursuit) I owned

        We set up huge autocrosess there, joining multiple runways at times. We also had lots of fun at nearby Texas World Speedway (TWS) running annual time trial events we called Aggiecross. This little college club was holding Time Trials back in the late 1980s, which didn't happen in NASA for decades. A lot of us worked at TWS while we were in school, and when we worked corners for PCA HPDE events we got free track time in our clunky, broke-ass student cars as well.

        Left: My ex-pursuit 1987 Mustang LX 5.0 was one of 6 Foxes I've owned. Right: Amy's 92 Mustang GT and my 1969 Mustang (C Prepared)

        During my time racing with TAMSCC, both during college and after, I ran in a variety of cars. Since I was the proverbial "starving student" while in school many of these cars were crappy and cheap, but most of them still V8 powered and RWD. When I met Amy she had an 86 RX7 but once she raced in some of my cars she jumped to Mustangs and then Firebirds. Between us we've owned about 16 pony cars (Camaros and Mustangs) of various years, from 1969 through 2013 models. Two years after graduating I landed my second post-college job, which allowed me to commute from the same town (College Station). I was making great money in an oil field mechanical engineering position, and had extremely low living expenses. At one point there I owned 7 cars, including two project builds and an immaculate two year old Corvette (the white 1994 shown above).

        Left: Amy's supercharged 1994 Trans Am on 17x11" HREs. Right: Her 1998 LS1 Formula

        I tell you this because knowing what I used to own and race in my "Pre-Vorshlag Days" (nowadays I typically do NOT buy the cars I want but instead buy cars that need suspension development) helped clue in some old friends that knew this was to be a LOW budget build, but that somehow I knew it would be fast. Three amigos of mine were the ones to ferreted out the last few clues and got to the correct answer without question, before I confirmed it to them privately. These guys knew me too well, and were more racers from my days running with the TAMSCC: Matt Miller, John Scheier, and Doug Willie

        Yet nobody correctly guessed that we'd keep it in TTC class.

        Project Danger Zone Is...

        So get on with the answer already! Sheesh...

        This is the car we're building. It looks great, from this angle. This photo was staged perfectly - its a mess from any other angle!

        This is it. What you are looking at is a 1992 Chevrolet Corvette 6-speed that is bone stock, except for being stripped of a nasty old interior. This is a base trim level car with the factory 5.7L "LT1" (Gen II) 300 hp iron block V8 and ZF S6-40 6-speed manual transmission. It has the strong Dana 44 rear axle assembly (not the Dana 36 that came in the early C4s and automatics). This particular car has 68K original miles and from the angle shown above doesn't look at all like a $2000 car. Regardless of how clean it looks now it was still a hot mess when purchased.

        The entire interior is gutted, even most of the dash. We will finish what was started and put the dash cap back on

        I will go over the issues on this specific car as we chronicle the repairs and upgrades to it this season. The previous owner (Brian Matteucci) has done a lot of repairs and refurbishment, and even a couple upgrades but we still have a laundry list of safety updates to tackle, as well as a few performance mods to "max it out" for TTC class points. We are keeping the car legal for TTC class so there aren't a whole lot of "points" we can burn on upgrades, so the car will remain stock in many aspects. Luckily, a stock 1992 Corvette doesn't suck!

        Why is the C4 Still A Worthwhile Track Rat?

        To understand why we consider this 24 year old car still relevant, we need to look at how this car was designed and what it came with that was ahead of its time. Here is a brief look at the C4 generation Corvette, which was produced from 1984 to 1996.

        We're already getting to work on this 1992 Corvette at Vorshlag. Parts are ordered and it was detailed by yours truly

        GM calls the Corvette chassis the Y-body and it has been produced from 1953-current in 7 distinct chassis generations (see the Corvette Wiki). The "C4" generation was designed in the early 1980s and was delayed a bit before launched as a 1984 model (there was no 1983 Corvette). This chassis was a huge leap in sophistication from the C3 chassis it replaced. None of the subsequent Y-body chassis were this revolutionary - C5, C6 and C7 all share design aspects of the C4 and are instead mostly refinements (yes, the C5 had some serious updates!). The C4 was the first "Billion Dollar Chassis" design in the history of automobiles - and it doesn't share anything with any other GM chassis, so there was nothing to be gained for another, mass produced chassis (exception: almost all engines developed in the Corvette make their way into the F-body chassis and others).

        With fairly low production numbers each year this has got to be a "loss leader" for General Motors at only about $40,000 when this car was new in 1991. And now with 3 newer generations of Corvette following the C4, this chassis has bottomed out in resale value - its not old enough to be considered a classic but its not new enough to be worth a lot of money. Some year C4s can be had for next to nothing, and even the later C4s can be snatched up cheap if it has any issues (like this one) and made into a low buck race car faster and more sophisticated than 75% of the cars at any given NASA race weekend. And this 1992 model one of the best of the C4 generation.

        Engines: The C4 had 4 major engine designs in its 13 year run (1984-1996), which began in 1984 model with the abysmal Cross Fire V8. This was a horrid, 205 hp, early attempt at a fuel injected V8 and a complete carryover from the outgoing 1982 C3 Corvette. The Crossfire L83 has ZERO redeeming qualities and was only used for one model year in the C4. Starting in 1985 was the 5.7L L98, better known as the Tuned Port Injected or "TPI" V8. These long runner intake equipped V8s had LOADS of low end torque but petered out above 4000 rpms. With aluminum heads this "Gen I" Small Block Chevy (SBC) made decent power for the early 1980s (230 hp then up to 250 hp) but stuck around far too long (through 1991 model).

        This was followed by the revolutionary 300hp 5.7L "LT1" Gen-II V8 in 1992, considered the first new design in the Small Block Chevy's long history (hence the Generation II engine; the LS1 in 1997 was the Gen III). There's tons of data out there about this motor, of course. In 1996 there was a special edition version of this motor called the "LT4" made 330 hp. Lastly, during the middle of the C4 model run was the LT5 DOHC V8 that came in the ZR1 (1990-95, 385-405 hp), which was a technological marvel for its time but was quickly overshadowed by the all aluminum OHV V8 that came out in the C5 - the LS1.

        The Gen-II LT1 engine was unique in that it only lasted 5 model years, but it was also used in the 4th Gen F-body (1993-97 Camaro/Firebird) and the Caprice/Impala (1994-96 B-body) as well as one Cadillac (1994-96 Fleetwood). The reverse flow cooling was a big change but other than the bump to 10.5:1 compression ratio, produced very little benefit, and this "reverse" cooling style (heads cooled before block) was dropped in the Gen III LS1. The distributor (Optispark) is very unusual; it is driven by the camshaft and tucked behind the water pump. It is somewhat problematic and prone to water damage, but the later '95-96 "vented" style works better and aftermarket versions better still. The intake manifold is about as far from the TPI motors as you can get - it has larger but very short runners which produce a higher RPM range and a much flatter torque curve than the tractor motor curve of the TPI.

        The Y-body LT1 always got 4-bolt main bearing caps (the other's all had 2-bolt mains), but the 1992 Corvette's LT1 is unique in one key way. The TPI motors (1985-1991) all used a crude form of Fuel Injection called batch fire port injection, and used a Mass Air Flow meter to meter incoming air into the engine. These early MAF designs used a circuit board that was in the airstream and were problematic from day one. The 1993-96 Y-body and 1993-97 F-body LT1/4 engines went to a more modern hot wire element MAF with the electronics housed outside of the airstream. But for the 1992 Corvette (and 1993 F-body) this new EFI system wasn't ready and for one model year only GM went with a speed density air metering system (no MAF). This uses Manifold Pressure Sensor along with a atmospheric pressure sensor to read incoming air. This lack of a MAF means a lack of a restriction in the airstream for that one year - and the 1992 model ran the strongest of all of the LT1s in stock form.

        The manual transmissions used in the early C4s (1984-88 models) was a Doug Nash designed "4+3" transmission – a 4-speed manual coupled to an automatic overdrive on the top three gears. It was designed to improve fuel economy but was mostly a steaming pile of crap. For the 1989-96 model Y-bodies, GM went to the Germans and they offered up the S6-40, made by ZF. It is an unusual transmission and parts are hard to come by, and shops have popped up like ZFDoc that specialize in rebuilding these brutes. This trans is nicknamed the "ZF6" and is big, heavy and very strong, if a bit noisy. With 6 speeds and 2 overdrives (.75 in 5th and .50 in 6th), it made for excellent fuel economy. The Borg Warner/Tremec copied these overdrives for the later T56. With the ZF6 tall 2.68 first gear, the "black tag" version is rated to withstand 450+ ft lbs of torque (and is much stronger with a modern carbon synchro upgrade). To quiet the noises, GM used a heavy dual mass flywheel, which tips the scales at over 40 pounds. The clutch is also strong and the Dana 44 rear differential out back is also a brute. The limited slip unit in these 44s tends to last decades... and I hope so because we're not touching it. The halfshafts are big beefy aluminum tubular units with U-joints (cheap to replace!) instead of CV joints, and the driveshaft is built the same way.

        The body is fairly aerodynamic (low height, low drag, small front area) and works well at high speeds. The body panels are made of fiberglass - which is good considering it has some chunks missing, and fiberglass is easy to repair. Some damned fool drove this car through a barbed wire fence back in its' checkered past, which damaged the front bumper cover and body panels on the left side. The driver's door was trashed but the replacement doesn't match the car's white paint well, so that will likely get repainted at some point. I will patch the fiberglass that is damaged myself and prime it for later repaint.

        continued below
        Last edited by Fair!; 12-29-2014, 06:07 PM.
        Terry Fair -
        2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
        EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


        • #5
          Re: Vorshlag Budget TT Build: Project DANGER ZONE

          continued from above

          Where Did This Car Come From?

          So about 3 years ago an old friend, Brian Matteucci, wanted to build a NASA Time Trial car. He was a long time autocrosser and former SCCA W2W Club Racer and watched what we were doing in NASA. He liked the cost-to-seat-time ratio of the TT series of classes, which was why we were in it as well. I helped him understand the NASA TT rules as well as the confusing TT classing formula and points classing system. We bench raced several builds over a few weeks and came up with the C4. That was no accident - because we had both raced these in the past. My history with Matteucci goes way back to about 1989, when he was a racer in the Texas A&M Sport Car club racing in a notchback 5.0L Mustang... I was about a year ahead of him and happened to be racing the same exact type of car.

          We were competitors and friends through college, both helped create a new and popular autocross class called Super Street Mod in 1990 (we used this class to help push the SCCA to create Street Mod), and were roommates after college when we both worked at our first jobs in Houston as engineers. He and I both used to love digging through rule books looking for ringer cars and rules to exploit. After college we both autocrossed C4 Corvettes for a time - he was in a 1987 Z51 while I raced a 1994 Z07, both in SCCA's Super Stock class. When his 87 Corvette's fuel pump died on day 2 at Solo Nationals one year he co-drove my C4 - and hated it.

          My 1994 Corvette Z07 running in Super Stock at Solo Nationals in 1998. It was on Hoosier DOTs but was otherwise bone stock

          The differences between our cars was dramatic back then - at low speed autocrosses - but it was obvious to both of us that the LT1 was far superior to the TPI engines at higher speeds. Already owning a C5 Z06, when he suggested a letter class TT build 3 years ago I immediately suggested another Corvette, but one that was a 100% dedicated, no-compromise race car build. Jason and I here at Vorshlag had often talked about the TTC classing of the late C4, and after some discussion with Matteucci, he agreed that it had a lot of potential in this class. He went out and bought this mess for $3000, sold off the interior bits for $1000, and had a $2000 platform to build a TT lettered class car from.

          During the next 2-1/2 years Matteucci proceeded to strip hundreds of pounds out of this car and replaced lots of broken OEM bits (24 years can take its toll on anything), while testing it at various autocross events along the way. He did this while he was very busy with work, building a new house and shop, building a chump car, and autocrossing his C5 Z06. In December 2014 he got to a good stopping point and I bought the car for a great price - along with a promise to let him co-drive the car with me in NASA TT. Amy and I did that last year and it was a good way to get us both out on track for less money spent - which fits this project well.

          With our "Team Vorshlag" entry we can both drive the car for one entry fee, doubling the chances for a fast time (two sets of eyes and brains are better than one). Matteucci worked at Roush Engineering for several years, and while there was responsible for building and developing a fleet of Bonduraunt school cars when Ford was their supplier in the 2000s. He lived at the track for many months, driving these cars for hours every day, so he's no stranger to finding a good track set-up: he was paid by one of the biggest engineering/racing companies in the world to do just this.

          Left: The factory power steering cooler is a huge double-pass unit. Right: I pressure washed underneath to help find an oil leak

          Last but not least, Matteucci was also the designer of our first three initial camber plate designs when he started Motor-Force Engineering back in 2002. We bought his company (and IP) back in early 2006 and several of the current Vorshlag camber plates can trace their roots back to his initial designs. Other than some manufacturing aspects and tweaks to materials and coatings, they are for the most part unchanged. So he has a long history with me and Vorshlag, whether he wants to admit it or not, heh. When I picked up the car on December 20th I gave him a bunch of Vorshlag swag, which was part of the deal with the car - he has to wear this stuff at the track, especially if he is the one who gets the wins!

          TT Classing Looks Solid

          So if you look at the NASA TT (and PT) classification for Corvettes something jumps out at you (go to page 20 of the TT rules) - most Corvettes either require a dyno test for an initial base classing (C1-C3) or are just shoved straight into TT1/2/3 numbered classes (C5-C7). The lone exception is the C4 generation, which has 5 separate letter class listings:

          MODEL........................................BASE CLASS...... MIN WT
          Corvette C4 ('85-'91)............................ TTD**......3223
          Corvette C4 ('92-'96) (LT1)................ TTC*.......3203
          Corvette C4 (LT4 option) (330 hp)...... TTC**......3350
          Corvette GS ('96).................................. TTC**......3350
          Corvette ZR-1 ('90-'95).......................... TTB*........3500

          While the TTD entry for the 1984-1991 "TPI" Corvettes might look the most attractive place to start at first glance, the minimum weight is higher yet they make a lot less power (230-250 hp) than the LT1s. With two stars it is already -14 points out of 19 in TTD class, and strapped with TTD's 245mm base tire size, so it would be nearly impossible to stay in TTD class, meaning it would need a lot of work to be competitive in TTC. Of course upclassing adds 20 points to play with, so it might make the 12:1 power to weight ratio of TTC, with some dollars and points burned on engine upgrades. The two LT4 powered cars (all 1996 6-speed cars and the '96 GrandSport) have an extra star (-14 points in class) and extra 150 pounds of minimum weight, but the only advantage being +30 hp over the LT1 it is not ideal (plus they are worth more money used). Likewise the ZR1 has +300 pounds more minimum weight (and boy were they heavy!) and its up a class (TTB) and has one star (-7), plus these are somewhat rare and pricey, and expensive to maintain and upgrade. Yuck.

          So the lighter, rugged and simple 1992-1996 LT1 cars are really the best bet, in my mind. TTC seems like an odd place to class the 1992-96 LT1 Corvette - and it might well be, but it is pretty old and I doubt many (any?) have been competitively run in NASA TT or PT. We shall soon find out if this base class makes sense, because that's where we are going to run it.

          TTC 1992 Corvette Build Basics

          While several folks guessed we would be building a "C4 in TTB", nobody guessed the TTC angle. And why would you? With the base classing of TTC* we only have 14 points to play with in class, so how could it be as "fast" as I predicted? For one, it doesn't need any points spent on power mods to meet the max power-to-weight ratio, as it will easily make the 12:1 limit for the class. So we save points there. How do I know? I owned a nearly identical 1994 Corvette that I had dyno'd on a modern DynoJet, where it made 277 whp in bone stock form, back in 1996 (these cars were a hair under-rated at "300 hp" crank). Another TAMSCC racer (Mike Mclure) owned a 1996 LT4 Corvette and dyno'd it at 308 whp the same day on the same dyno (also under-rated by the factory). If you know your dyno numbers, you will see that the LT4 makes almost exactly what a stock LS1 makes in a C5 (~310 whp), and the LT1 just a little bit down on that.

          Left: The 12" front brakes are adequate but can be upgraded to 13" rotors "for free" (no points). Right: The ABS system is ahead of its time

          The factory brakes are also ahead of other cars from this era and not much if any off of the C5. GM developed its best ABS systems on the Y-body and this 1992 model has one of the best of the generation. And while the 12" diameter front brakes seem a little wimpy on the Base Trim Model, which this car has, they aren't total junk. The calipers are twin piston floating PBR units, a cast aluminum design used on the Y-body, F-body, and even the SN95 Mustang Cobra, to name a few. We have found a way in digging through the rules and Base Trim Level of the 1992-96 Corvettes to upgrade the discs to thicker, 13" diameter discs for zero points (more on that soon), so that saves us points and only costs a few dollars.

          We will show better suspension pics in the next update, but these will do for now

          Suspension is very advanced for the time period, and better than what many of us race with on brand new cars from today. Forged aluminum uprights at both ends pivot on double A-arms up front and a multi-link rear IRS. Both ends are sprung by a composite transverse leaf with factory monotube Bilstein dampers. Other than some freshening and an alignment we're going to leave that pretty much alone.

          Last up is the tires. The late C4 was designed to house massive wheels and tires (factory used 17x9.5" on almost all packages and up to 17x11" out back). While we won't be making flares to house big wheels, which is kind of one of our "go to" first mods, we will blow almost ALL of the available class points on tires (more on that next time).

          Why not bump up to TTB? Sure, we think this car could be just as competitive there at this class' more aggressive 10.5:1 pounds-per-hp ratio, but it would allow for a lot more mods, and that costs $$. The goal of this is to keep costs down, but with +20 more points to play with after upclassing we could easily spend an extra $10,000 chasing down the points and the top cars in TTB (S2000 + E46 M3). While this would be fun, that's not our goal for the 2015 season. We want to instead focus on the "free mods" that TT allows as well as spend our precious 13 points as wisely as we can, as well as show some of our best "race prep" and safety upgrades - that are the same for virtually all classes.

          In the next post we will sow our first few mods - brakes and shocks - that are both zero point upgrades. We will also show our first point mod and show the behind the scenes upgrades and race prep.

          What's Next?

          I always close my build thread posts with a teaser for the next entry. Well we haven't done much to the car yet, so there's still a lot of track prep to knock out. We did order OEM replacement brake parts and shocks, all zero point upgrades which I will explain in my next post. The next biggest things the C4 needs before the first event are all safety related.

          In early 2014 our crew here built the cage and did all of the fire/safety/lighting upgrades for a 1987 Corvette convertible that was initially run in Lemons and Chump but lately has been competing in WRL series endurance events (also known as - the Poorvette). We learned a lot working on that car that will apply to this TTC build, of course. One of the items we will replicate on our car is the roll cage, but due to time constraints (3 weeks to go!) before the first race we will only make the main hoop, harness bar and rear downbars (4 point roll bar) for now.

          We will go back and complete the full roll cage structure this car after the first event, to make everything safer (and to add some more ballast weight). Unlike this black 87, our 92 C4 has a roof - but its just a bolt-on targa panel, like all hardtop C4s. That removable roof panel makes it easier to build the cage and provides some aerodynamic advantages over the drop top, but the rear (glass) hatch main roof support structure will still be in the way and make this one a bit more challenging to build.

          Left: This is the seat we'll be using in the TTC car. Right: An adjustable seat back brace is visible in this pic

          Another area that needs some attention fast is the seat mounting. The OEM seat that came with the car BROKE at an autocross event, which Matteucci warned me about ahead of time. We bought this Kirky 56700LW aluminum seat (see above left) for the Poorvette, but the driver wanted something different so we were stuck with it. This TTC4 project will get a lot of those cast away parts, some of which are brand new. Since the seat is a touch on the big side (17" width) we will make a poured foam seat insert, as well as a seat back brace tied to the cage (see above right)

          Due to the weird floor structure of the C4 chassis (some parts are composite and some are sheet metal), and some damage from a previous owner (aka: the Crack Head that tore up the interior and drove through the barbed wire fence), we need to repair and reinforce the floor areas. These cars are tricky to safely mount a racing seat into, as well as ballast plates, both of which we will need to do. The car is already 200 pounds under minimum weight (including a 200 pound driver) and that will only worsen as we (legally) replace OEM body panels and rear glass with lighter weight alternatives. We will run this car at the 3203 pound stated minimum weight and NOT burn points on running a lower weight. Running lighter might seem advantageous but we would have to lower the power output as well (the 12:1 ratio doesn't change for TTC class even if you burn points to "run lighter than minimum").

          Two zero-point mods Matteucci already added include the Moroso 20185 road race LT1 oil pan (allowed under TT rules, page 36), which at $288 includes more capacity, a Kicked-Out Sump and Trap Door Baffling for improved oil control, built-in Windage Screen and a port for an oil level sensor. The QuarterMaster 7.25" triple disc clutch ($599) and flywheel are also zero point mods (see page 36) and knocked nearly 50 pounds out of the drivetrain mass. It makes this little LT1 rev quite nicely and shift very well at speed - but driving it around at low speeds is a BITCH and it unlocks a LOT of transmission noise. Don't have accurate pics of these mods yet, but when we take them apart I will get better images and weights. I will include these "zero point" aftermarket part upgrades costs into our build budget, below.

          WHAT'S NEXT?

          That's all for this time. I will post another update before the first race, January 17th at MSR-Houston, where we will debut the car in NASA's TTC class with me and Matteucci at the wheel. That's assuming everything goes smoothly! The next update will show some actual work being done besides my initial clean-up, and I will also lay out more of our game plan for the season, including which tires we plan to run with. They are 30mm smaller the stock size, but it will make sense why soon.

          Last edited by Fair!; 11-06-2018, 10:07 AM.
          Terry Fair -
          2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
          EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


          • #6
            Re: Vorshlag Budget TT Build: Project DANGER ZONE

            Project Update for January 9th, 2015: The first stage of "initial race prep" for this project is getting down to the wire with the NASA race debut only ONE week away! Let's get caught up on the work we've been knocking on Project DANGER ZONE, our TTC class prepped 1992 Corvette. I had intended this to be a quick update, showing the initial stages of race prep, but I started writing and somehow this post spiraled out of control. It now includes some aero/drag reduction theory, the History of Iron and Steel, a good bit on roll cage tubing and design, some tire analysis, and other random tidbits of tech. If you get bored easily just skip down to the pictures and enjoy.

            Safety First, Kids!

            There are many Safety Upgrades we want to add to (or repair on) this Corvette during the 2015 season, which are the same for virtually any dedicated road race build. Unfortunately we were pressed for time and won't get them all done before the first race. The Safety list includes: a full roll cage, racing seat install, 6-point racing harness, window nets, full fire extinguisher system, secondary 2.5 pound fire bottle, tow hooks at both ends, tie-down hooks at both ends (for towing), replace the broken windshield, replace the rear hatch glass with Lexan or Plexiglass, and more. That's a lot of parts and work on the "Punch List", but as far as what's "required" for NASA Time Trial, that is much less. We also have some repairs and performance upgrades to tackle, too. We got almost nothing done over the holidays (short weeks, busy on customer cars) so let's see what we can get done in two weeks.

            Windshield + Small Aero Improvements

            This repair is really a safety upgrade, because you cannot race with a busted windshield. Before I bought the car from Matteucci he had warned me about this problem - it had a lot of big cracks on the passenger side and chunk missing where the OEM rear view mirror attached, with the cracks propagating into the driver's view. The upper right corner of the windshield trim and weatherstrip took a hit when a former owner (ie: The Crackhead) drove it through a barbed wire fence. Matteucci literally found a crack pipe (maybe a meth pipe) in the car after he bought it. So yea, now you understand part of why this was a $3000 running and driving car purchase.

            Nasty, broken windshield and trashed weatherstripping has to be replaced

            We discussed delaying the windshield replacement because when you install a roll cage it is ALWAYS easier (and often required) to get the front windshield out of the way to access and weld tubes along the front of the cage. In some cars with a fixed rear glass window, that is often removed as well. The cages we built in the two cars below required the windshield to be out. At left is an SCTA legal cage for 200+ mph use on the salt flats, which has more of a "Funny Car" drag racing cage (built per the rules). To weld in the the front tubing gussets requires windshield access. The one at right is a NASA ST3 legal Mustang the the dimple-die gussets and front corner tubes need windshield access - as does a proper paint job on any cage.

            We knew we wanted a roll cage in DANGER ZONE (to reduce the "zone of danger"), but with only 2 weeks of time build available after the short holiday weeks between Christmas and New years, and many other items that needed attention, meant only building a 4-point roll bar for this first race. Which meant the windshield didn't need to come out. But it was so cracked that it would never pass tech, so it had to be replaced. And when we go back and finish the full cage, out it will come again!

            We called our buddies at Titan Auto Glass and they extracted the old and busted and installed the new hotness. There are normally several windshield choices for most cars, varying in price, but for 24 year old Corvettes there was one - and it was a tick pricy at $260 installed. But hey, can't race with a busted windshield. Going to Lexan is an option but there are more downsides (more costly, harder to install, easily scratched, difficult to use wipers with them, more easily nicked by rocks or tire klag) than upsides (slight weight savings). A two layer, laminated, glass OEM style windshield is preferred by many racers when they have a choice.

            The OEM windshield surround rubber weather stripping was a total mess (above right). Matteucci had cut away the bits around the A-pillars when he gutted the interior and the top bit was destroyed by the barbed wire. The crackhead former owner had filled in the missing chunk in the rubber seal with SHOE GOO, and that had to be chiseled away (thanks Titan!).

            I wasn't about to put this mangled mess of rubber seals back on, but we needed the top bit of rubber to seal the targa roof panel smoothly along the top of the windshield and I also wanted the seals back in place along the edge of the windshield at the A-pillar. This should help smooth the airflow in a high payoff "Green Zone" of potential drag reduction - the edges of the windshield. Read this NASA Speed News article called "Getting Into The Zones" (page 60) written by aero guru Neil Roberts (also read his ThinkFAST Engineering blog for more great articles!) and that will make more sense.

            A smooth, new set of weather stripping should help aid the transition from the edge of the windshield (sides and top), reducing drag. We are looking to reduce drag in ALL of the Green areas (again, read Neil's article) on this car, and do so legally. We cannot run NASA events with the windows up, so the door window openings have to stay. We have tried to read the rules to say otherwise, but rule 7.2 of the NASA TT rules is pretty clear:

            7.2 Front driver and passenger side fixed/Lexan windows are specifically not permitted unless they are factory installed during the manufacturing of the vehicle. Both front side windows must otherwise be in the down position while on track."

            Running the windows UP would be a decrease in drag but it is not allowed in virtually any form of road racing, for safety reasons (easier extraction after a crash). Some drag racing classes and high speed events like Bonneville do allow for side windows, so the silver Subaru we're building the cage for above is getting a full Lexan window package (4 side windows + front and rear windscreens).

            Why Terry Needs A Roll Cage

            There isn't any additional safety requirements in NASA Time Trial groups than what is called for in HPDE run groups: a Snell SA2010 rated helmet and OEM seat belt, plus a roll bar for convertibles. There isn't supposed to be wheel to wheel contact in TT, but we are running for times and competing for contingency prizes, and many TT racers take it pretty seriously. I won six sets of Hoosier race tires racing in NASA TT3 class in 2014, and these were BIG tires that cost $1710 a set, so there is some decent swag on the line. When you are chasing a TT win you often push the limits and do stupid stuff...

            Crap like this

            My personal safety record, for the amount of laps I've driven on track, was pretty damned good up until 2014. In 27 years of running on road courses I only had a couple of "offs" that were worth mentioning. I de-beaded a couple of tires in a high speed off at TWS in the late 1980s that curled my hair a bit. A number of times I've had a quick "off and on" that bent a splitter or packed a grill with grass, sure. The stock brake pads came apart and I left Turn 7 at ECR at 90+ mph in 2013 in a stock '13 Mustang. But by far my most memorable off-track experience happened in 2014 (shown above).

            After the crash I began wearing a HANS device and fire suit to complement the FIA halo seat, 6-poiont harnesses and roll bar in our TT3 Mustang

            I briefly mentioned this in my first post, but it was a pretty spooky incident and I figured it might explain my "overkill" safety requirements for this TT build. After losing brakes at at Road Atlanta at a Global Time Attack event in May 2014, I went off the end of Turn 10A at 150mph, through the gravel trap, and took a big vertical hit coming out of a trap. I got hurt but the car barely took a scratch (splitter came off, was repaired and reinstalled and back on track 2 weeks later, but not with me driving). Even though I had a proper FIA halo seat, good harnesses, and a good roll bar, I wasn't wearing a HANS device. We think this might be why I fractured a vertebrae in my back and broke a rib. After this incident I was in a lot of pain, wearing a back brace for 2 months, and not racing.

            Having gone through the crash scenario many times and analyzing frame-by-frame pictures of the crash since, the injury seems to come down to too much "arching" of my back in the impact that broke these bones. A properly worn HANS device would have likely prevented this injury. The "off" happened because I ran out of brake pads, and had been ignoring measured brake caliper temp data of 490°F+ for months. I'm not going to make those series of mistakes again, and I also vowed in 2014 to start racing with better personal safety gear. I was setting a bad example and I needed to do better.

            So obviously, after this back-breaking scare I'm taking my safety on track a lot more seriously. I've starting using a HANS device (still haven't picked my favorite model after trying 4 different brands - and I'm about to try the brand new Schroth HANS design, since we are a dealer) and an FIA 3-layer driving suit in all TT events. I am also wearing my harnesses TIGHTER and keeping a much closer eye on things like brake fluid temps and brake pad material depth, so this scenario of failures never happens again.

            Roll Cage Is Safety More Than Performance

            The steel frame structure of the C4 Corvette. This is a 1984 model

            After the personal safety gear, the next most important safety aspect of any race car is the roll cage. This structure is helpful to make the chassis more rigid, sure, but it is there mostly to prevent bodily injury in many types of crashes and "offs". These include single car off track frontal collisions with a barrier (somewhat common), a roll-over crash (very rare), or any car-to-car contact (more common). While a roll cage wouldn't have helped me in my gravel trap "jump" incident at all, there are other types of crashes where it could save your life - and do so more effectively than the basic 4-point roll bars we have used in my last 3 personal race car builds. I own a shop that builds roll cages and haven't had one in my own cars in 6 years... that's crazy.

            Corvette roll cages are tricky. All Corvette chassis generations (C1-C7) have a strong metal frame (steel frames through the C5, with aluminum frames for C6 Z06 and all C7s) with a composite body attached to it. Adding a roll cage to these cars has some extra challenges, since you need to cut away fiberglass to access the metal frames, but its nothing we haven't done before.

            As I spoke about above, TIME is not on our side for this first NASA event, so we had to cut back on the roll cage plans for the maiden voyage. We could have bought a second-hand 4-point roll bar but it would never fit as tight to the roof structure in this gutted car (they are usually made for full interior cars).

            Frame differences on the 1984-1991 (left) and 1992-1996 (right) C4 Corvettes

            Quick sidebar: the C4 Corvette had major changes to the suspension (1989) and even to the frame (1992), along with major changes to the drivetrain (1989 for ZF and 1992 for LT1), front crossmember, and transmission tunnel over the 13 year long model run. The two "body shop spec" images above show the changes to the frame at the 1992 model year, and we've noticed a lot of other differences to the interior fiberglass structure.

            Last year we caged and safety prepped a 1987 Corvette convertible (shown above) and after looking at pictures of both that and our 1992, it had a lot of structural differences at the tunnel, firewall, and rear bulkhead (behind the front seats), not to mention the dash, body, and other obvious differences. The frame was also different in some key areas. We are using the NASA CCR for cage design specifications on our car, but the black 87 used a mix of NASA, WRL, Lemons and ChumpCar series cage rules.

            A Brief History of Iron and Steel

            OK, this is a big tangent. It might not be boring to a racer - unless you are a metallurgical engineer. Modern race car roll cages are made from steel tubing (aluminum is not allowed) and picking the right alloy and type of tubing for the job involves both a rule book (General Competition Rules or GCR/CCR) and some engineering knowledge. There are generally TWO accepted types of tubing allowed for roll cages in SCCA and NASA: 4130 Alloy steel and 1018/1020 Low Carbon (aka: Mild steel) Steel DOM tubing.

            Working as a Mechanical Engineer at a foundry in my first job out of college exposed me to a lot of practical metallurgical design and lots of different steel alloys. I also took a welding class at college, where we talked a lot about steel and iron and the changes welding can do to metal's molecular structures. That's where I learned that steel is the best metal on planet earth, and in many ways unique among all metals.

            Iron is is, by mass, the most common element on Earth, forming much of Earth's outer and inner core (same scenario in almost any rocky planet). It is also the fourth most common element in the Earth's crust, which means it is relatively easy for humans to get at and mine. The production of iron by humans began sometime around 2000 BC and was so significant it began what is now called the Iron Age - when iron replaced bronze in implements and weapons. This shift occurred because iron, when alloyed with a bit of carbon, is harder, more durable, and holds a sharper edge than bronze. For nearly four thousand years, until replaced by steel after ~1870, iron formed the material basis of human civilization in Europe, Asia, and Africa. Iron has shaped human history for the past four thousand years, and it's use accelerated technological growth.

            Natural "iron ore" has a lot of oxygen in it, so it is smelted at high temperatures to extract a more pure mass of iron. Carbon naturally gets mixed in at these high temperatures (along with 2-3 other elements) which means cast iron has a relatively high proportion of carbon (3-4.5%). This makes cast iron hard and brittle; it is liable to crack or shatter under a heavy blow, and it cannot be forged.

            Blacksmiths learned to work iron - after heating it in a furnace at high temps they removed a pasty mass and hammered it on an anvil to drive out the cinders and slag and to compact the metallic particles. This Wrought iron (“wrought” means “worked” or hammered) contained generally from 0.02 to 0.08% percent of carbon (absorbed from the charcoal), just enough to make the metal both tough and malleable. Wrought iron was the most commonly produced metal through most of the Iron Age.

            Steel alloys have a little bit of carbon in them (0.2 to 1.5%), enough to make them harder than wrought iron, but not so much as to make it as brittle as cast iron.

            continued below
            Last edited by Fair!; 01-09-2015, 03:33 PM.
            Terry Fair -
            2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
            EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


            • #7
              Re: Vorshlag Budget TT Build: Project DANGER ZONE

              continued from above

              Its hardness combined with its flexibility (from some other alloying elements) and high tensile strength make steel far more useful than either type of iron: it is more durable and holds a sharp edge better than the softer wrought iron, but it resists shock and tension better than the more brittle cast iron. After about 1856 (the invention of the Bessemer converter) and into the 1870's (Andrew Carnegie's grasp of the vital importance of chemistry in steel making) steel alloys became cheap to manufacture and exploded in use, replacing wrought iron rails in railroad tracks and other uses.

              Some of the sources I used, other than past knowledge: This and this and that, and more.

              Modern Roll Cage Steel Choices - 4130 vs 1020/1080 Alloys

              There are two basic steel alloys used in roll cage structures and we will start with the "stronger" and more expensive alloy allowed: 4130. AISI 4130 alloy steel is about 97% Iron and has 6 other alloying agents that make up the last 3%. Chromium (0.80 – 1.10%) Molybdenum (0.15 – 0.25%) are the two key elements added that give this metal its higher tensile and yield strengths, and are the two most expensive elements in the alloy as well - hence the nickname "Chromoly Steel". These alloys are harder to weld properly (generally they are only TIG welded) when compared to Low Carbon/Mild steels. The yield strength of 4130 is 66,700 psi (67 KSI) and when this metal is used, a little LESS of this alloy is needed to achieve the same total assembly strength as Mild steel. It has a good strength to weight ratio, but the same density as all steels (all steel alloys and iron have nearly the exact same density, .284 lbs/cubic inch, due to the fact that all steel alloys are still almost entirely made of iron). In the past, roll cage rules allowed for thinner 4130 tubing to be used relative to Mild Steel, but that is no longer the case for most road racing bodies.

              I used to use a lot of "A36" mild steel 15-20 years ago when I designed oilfield equipment, which had a minimum yield strength of 36KSI, which is relatively soft and very cheap. The modern 10XX series steels have gotten better and a lot stronger - closer in strength to 41XX Chromoly steels, but without the negatives. AISI 1018 and 1020 "Low Carbon" or "Mild" Steel alloys (also known simply as Carbon Steel) are lower cost and slightly weaker than 4130, but these 10XX series alloys have excellent weldability and offer a good balance of toughness, strength and ductility. Once cold worked (via the DOM or CDS process) these Mild steels become even stronger and stiffer.

              1018 steel (0.14 - 0.20% Carbon) has a yield of 54KSI and 1020 steel (0.18-0.23% Carbon) has a 51 KSI yield - which isn't that far off of 4130 (67 KSI). Ultimately 4130 is about 20% stronger than Mild steel. But 1018 tubing that is DOM cold worked gets stronger, and is rated at 70KSI, and 1020 DOM tubing is rated is 65 KSI. Cold working 4130 tubing via the DOM process turns it up to 90 KSI yield... roughly 22% stronger.

              The key benefit to racers building roll cages out of Mild steel over Chromoly is that 10XX alloy steel is much more forgiving with respect to weld embrittlement and tends to "crash better" than the harder "alloy" steels. When you weld the 41XX series alloys the molecular structure of the alloy changes near the heat affected zone, especially if you put too much heat into the weld (and some welders like to "weld hot", which can really make the weld area change), so 4130 cages are almost exclusively welded with the trickier TIG welding process (a Tungsten tipped torch with a shielding gas and a separate metal rod, with a variable control on the welding arc).

              Mild steel isn't nearly as susceptible to this issue and can be TIG or MIG welded and generally does not lose much strength at the welded joints. 10-20 years ago 4130 was all the rage for roll cages but lately 1018 or 1020 Mild steel is the norm, as long as they are DOM. To me nothing beats a properly designed, TIG welded, Mild Steel DOM tubing roll cage. This has the best combination of variables and the least number of compromises.

              DOM vs ERW Tubing?

              ERW or "Electro Resistance Welded" tubing is how steel tubing and pipe is made (at least initially) - where a continuous, flat roll hot rolled steel is bent around round (or square or rectangular) dies and welded at a seam (see image above). That's how lower cost pipe and tubing is left - with this visible welded seam on the outside and often a physical "ridge" on the inside of the tube (see below). This problem is - seam ultimately becomes the weakest point in this type of tubing. And the hot roll plate material isn't ever as strong as cold worked steel.

              A visible seam and often a raised ridge is the result of the welding process from ERW tubing. All tubing starts as ERW...

              The DOM process (Drawn Over Mandrel) takes ERW tubing and "cold works" it by drawing over a round mandrel and through round dies, inside and out. This makes the now DOM tubing "seamless" (its really hard to find the seam with your eyeball) and work hardens the steel structure - adding strength and removing the stress riser at the seam. ERW tubing was previously allowed in roll cages (up until just a few years ago) and the various CCR/GCR rules sometimes still reference ERW for "grandfathered" cages built before it was outlawed, but nowadays all roll cages are spec'd as seamless tubing - either 1018/1020 Mild Steel (DOM or CDS) or 4130 Alloy steel (DOM or CDS). There's another cold working seamless tubing process nowadays called CDS (Cold Drawn Seamless), but I can't seem to find any CDS tubing in common roll cage sizes - yet. The CDS specification seems to be more common in Europe. It could be the exact same process as DOM, but some U.S. tubing companies specify them separately, so I don't know.

              The stiffness difference between ERW and DOM is shown in this video, with the same diameter and wall thickness tubes of both types in a side-by-side bending test. The lower strength of ERW + the stress riser of the seam are why it isn't specified in roll cages any longer, but it was a pretty recent deletion from roll cage specifications.

              The FIA has updated their specified tubing to 350 N/mm2 (50.76 KSI) tensile strength (see page 46, rule 8.3 of Appendix K here), and material is simply listed as "Cold drawn seamless carbon steel". They used to only spec 4130 alloy tubing (or the European equivalent) but even the French have seen the benefits of using Mild Steel DOM/CDS tubing. As we have seen with changes to rules specs, ERW is no longer allowed and the advantages in welding Mild Steel outweigh the weight savings or 20% strength benefits of 4130 Chromoly.

              Picking the Tubing Material, Tubing Sizes and Cage Design Layout

              OK, that got a bit long, but it was hopefully worthwhile tech. Now that we know why we use steel, know more about the alloys, understand the benefits of the cold working and seamless processes that are required in the steel tubing specified, and why more cages are using mild steel DOM - let's pick the cage tubing size for this build and show some Corvette cage pictures already!

              Many of the cars we work on at Vorshlag lately, that are built around NASA specs, weigh over 3000 pounds so we're often using 1.75" diameter x .120" wall thickness DOM Mild steel tubing. And since the 1992-96 C4 Corvette is listed as a base class of TTC and a Minimum Competition Weight of 3203 pounds, I assumed that we had to use this tubing size. This is nearly the heaviest cage tubing in all of the NASA CCR, but lower weight cars can use thinner tubing diameters and wall thicknesses, as shown below (copied from the 2015 NASA CCR).

              NASA 15.6.18 - Roll Cage Tubing Sizes

              For the purposes of determining roll bar tubing sizes, vehicle weight is as raced, but without fuel and driver. Minimum tubing size for the roll
              cage is:

              Up to 1500 lbs:
              • 1.375” x 0.095” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM
              • 1.500” x 0.080” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM

              1501 - 2500 lbs:
              • 1.500” x 0.095” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM

              2501 - 3000 lbs:
              • 1.500” x 0.120” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM
              • 1.750” x 0.095” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM

              3001 - 4000 lbs:
              • 1.750” x .120” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM

              Over 4000 lbs:
              • 2.000” x 0.120” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM

              Since we do not need to include the weight of the driver (200 pounds) or fuel (20 gal x 6 pounds/gallon = 120 pounds), that means our goal weight of 3203 really translates to a caged race car weight of about 2900 pounds. So we can use the lighter 1.75" x .095" wall DOM Mild Steel tubing. I like this for two reasons. First, we have a bunch of this tubing already in stock at the shop. And two, we typically bend 1.75" tubing, so our tubing bender has this set of dies already installed. Right now we're building two cages at once, both with 1.75" diameter tubing (one is .095 and the other is .120" wall), so we won't have to keep switching the dies. This thinner wall tubing is also easier to bend.

              We use a JD2 Model 32 manual tubing bender and dies

              The weight is not insignificant: 1.75" x 120" wall DOM weighs 2.089 pounds/foot of tube length. The 1.75" x .095" wall DOM weighs 1.679 pounds/foot (19.6% lighter and about the same amount cheaper). The other choice for this weight is 1.5" x .120" wall DOM, which weighs more at 1.769 pounds/foot. Sure, we could have stepped up to a larger tubing size, but those CCR minimums are there for a good reason... mega-sized tube in a smaller/lighter car makes for less room to the driver and less energy absorption in a crash, so we're going with the recommended tubing range for a 2900 pound car, then picking the larger tubing diameter of the two options given there, which is slightly lighter.

              Cage Layout and Design

              There are three cage design options we can choose form the NASA CCR, shown in 15.6.8, -.9 and -.10. We're going with the "Forward Hoops" version from 15.6.8, shown above. This is the most common of the 3 methods (another is the "Halo style") and makes for the most room for the driver's head in a car like this. So about halfway through the day on Friday the 2nd, our fabricator Olof stared work on the cage install. He will build a majority of this cage while Ryan finishes a cage on another car at the same time.

              Before you can start bending any tubes you have to clear out the interior. This car was already gutted, which saved us 15-20 hours of labor. That work is never included in the "cage" price, which some people don't always understand. If you want to save some money, bring in a NAKED car with zero interior bits, like this. I came in early that Friday and removed the driver's seat and targa top, then the guys pulled the rear hatch glass off.

              The driver's seat normally weighs more than this, but it was alreay partially gutted by Matteucci and only tipped the scales at 34 pounds - I've weighed a lot of modern power front seats in the 60-75 pound range. The targa top weighed less than I had thought at 22 pounds. This is the plexiglass "See through" version, but I'm looking for a fiberglass version (both were offered from the factory) which we could paint white to match the car, but they sell for $$$ used. The weight is mostly in the metal frame structure, so the Plexiglass vs Fiberglass is probably a wash - except the fiberglass OEM version is likely stiffer. We might replace the Plexiglass with a custom Carbon Fiber skin (stiffer than Fiberglass). Is it legal? Well since we can run with the targa top removed (wouldn't that make its construction insignificant?) and as I read TT rule 8.3.B, we can lighten the "roof, hood, body panels and doors" as long as they "maintain their BTM (Base Trim Model) size and shape". The "no points" listing for I.h.20 says the same thing, with more details with respect to carbon/fiberglass doors being legal as long as the BTM body lines, hinges and handles are still operational. And an in-house built Carbon Fiber roof would be, you know, cool...

              The rear glass was much heavier at 46 pounds. That bit will likely never go back onto this car, as we have a formed, 3/16", trimmed Plexiglass rear hatch replacement inbound that should save 30+ pounds. I will show that in my next post, if it gets here before the NASA race Jan 17th. This is legal per the "No Points Modifications" rule I.b.8, as long as it has the factory BTM shape and no uncovered holes.

              Once the interior was cleared out enough to start Olof began cutting bits of fiberglass out of the way. See why I had the pictures of the C4 frame structures up above? That was to help us find where the frame is - which isn't obvious in some areas as there are big gaps between the shape of the interior fiberglass structure and the metal underneath.

              If you ever get a roll cage quote on a Corvette, now you know why it costs more than a traditional steel unibody car - because you have to cut access holes to get to the frame. And they need to be fairly big holes, to give the fabricator access to weld a reinforcement plate to the frame. Then you have to close up the holes in the fiberglass later... all of that is extra work.

              Once you have access to the frame structure it has to be cleaned of all paint (we use a pneumatic wire brush tool called a "Crud Buster" along with a flap disc on an electric angle grinder). Then the plates are drawn in cardboard and transferred to steel, in this case 1/8" thick hot rolled plate (minimum thickness is .080" for these plates, but we tend to use .125", since it is stronger and easier to weld).

              Olof cut the plates and tack welded them to the frame at the main hoop, which is in an unusual spot. Normally the main hoop mounts to the floor behind the driver's seat - often 6-8+ inches behind the back of the seat. But in a Corvette, for tall-ish folks, the back of the seat ends up right at the rear bulkhead, so the main hoop has to go up on the rear deck area. The frame extends up here and we've checked with NASA inspectors on Corvette cage hoop placements and have also built cages in Corvettes like this. Miata cage main hoops are done the same way - just the nature of these 2 seat cars and their compact interiors.

              On Monday the 5th, Olof designed and bent the main hoop, with help from our head fabricator Ryan. They got the hoop TIGHT up against the high strength steel roof structure, and placed it back the correct distance from my head. We had already done a number of seat mock-ups at this point and we knew where I needed to sit - with the seat almost touching the rear bulkhead. This put the main hoop where it is above.

              continued below
              Terry Fair -
              2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
              EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


              • #8
                Re: Vorshlag Budget TT Build: Project DANGER ZONE

                continued from above

                By this point we had switched our focus from the larger Kirkey aluminum seat we had in stock, to a PORNO RED! Cobra Suzuka Kevlar FIA seat we "horse traded" with a friend for. My buddy Jason McCall had ordered this seat from us last year for his 1989 Corvette but it wasn't fitting with the electric seat adjuster he wanted to use (for better fit with his shorter co-driver - his wife). It is brand new and still good through 2019 on the FIA certification.

                This seat happened at the 11th hour - the day Olof needed to start on the seat mounting and to lay out the harness bar. It turns out our aluminum seat fits better in his full interior C4 and his composite Cobra seat fits better in my gutted C4 with no slider. So we made a seat swaperoo!

                Once more access holes were cut in the rear fiberglass (shown below left) the rear downbars could be cut, notched and built. These will land on 1/8" thick pads on top of the frame, as shown. Two thickness of pad, actually...

                One of the compromises made from our reduced timeline was that the cage became a weld-in 4-point roll bar, and then when we looked at the next step, it became a bolt-in roll bar. Now before you hurl insults, you have to realize that this is going to be a VERY beefy design that can still become a proper weld-in roll cage shortly after the first race. Weld-on "nut plates" (see above right) were created and access holes for the nuts were cut in the frame. This is because the frame is fully boxed and we couldn't bolt into the frame otherwise. These plates have nuts welded to the back side and will be seam welded to the frame, then a matching "footer" plate from the 4 main tubes will land onto these and bolt in place.

                All this bolt-in nonsense was done for future access. After our first TT event we have a month off before the SCCA Club Trials event at TWS. During this break we can take the time to turn the 4-point roll bar into a fully welded in 6-point roll cage. The front cage section and door bars take the most time to fit, and we ran out of time. But to do the final welding on the door bars and A-pillar tubes, the cage has to be rotated forward and down, and this bolt-in rear layout will allow for this rear section to be moved for that access. Once the final welding is done up front the four "footers" of the roll bar portion will be welded to the frame plates, and the bolts can be removed. Make sense?

                Yes, that's a little crazy, but our 2 week timeline was just too tight to fully cage the car AND do all of the other performance, safety and maintenance work needed. Next up in the roll bar design is the main harness bar (which the shoulder harness straps will wrap around), then the main hoop diagonal. This is a horizontal bar that is kicked back from the main hoop about 5 inches, to allow for the shoulder harness adjusters to loop around the bar.

                The diagonal bar was cut and being tack welded in right before I made this post on Friday Jan 9th. One more tube is needed for the roll bar (a short tube connecting the harness bar and diagonal) and then it will come out for TIG welding. All of the pictures shown were just tack welds, which were done with the MIG. I'll show the rest of the roll bar and all of the other work happening next week in my follow-up "initial race prep" post. Gotta wrap it up!

                Seat Mounting

                Mounting a racing seat into a car is NEVER a fun job - installing a real racing seat is always a LOT more work than you might think. Ask any race car fabricator and they will tell you that this type of job sucks. We've installed a lot of racing seats over the years and it is never an easy "bolt-in". Any off-the-shelf seat bracket we've ever seen usually needs massive modification, and some of them raise the seat height by 2-5 inches. They only seem to work for little tiny short European children. Its a dirty little secret in motorsports - bolt-in seat brackets for fixed-back seats almost never fit.

                And this only gets worse with drivers over 6 feet tall with racing helmets adding another 2-3" to their torso height. At 6'3", I'm not a good fit in many OEM seats much less with a racing helmet added. Here at Vorshlag there are 5 people that are 6'2" tall or taller, so we're all used to these seat mounting headaches. The Corvettes from C4-C7 are all pretty cramped inside as well, and we've had to really fight to make racing seats fit in these cars.

                In the most difficult situations (cramped cabin + tall driver) it is not uncommon to spend 6-8 hours fabricating mounts for one seat. Adding in a slider makes this take even longer, but we were out of room here and just mounted the seats directly to the floor (my co-driver Matteucci is almost the same height, luckily).

                Olof took most of a day to test fit the seat (with me sitting in it in a helmet), mock-up the angles and height, reinforce the floor, then modify the OMP side brackets (see image in this section) to get the seat bolted in where I had enough head room to the targa roof with a helmet on. It was tricky and he lowered the "lowest" mounting holes in the OMP brackets by about 5 inches. The original OMP seat mounting holes are crazy tall - doesn't matter what brand of brackets, this always happens.

                I don't have good pictures of the seat mounting from underneath, with the car in the air, but we have beefed up all of the seat mounting points to the chassis. The rear studs were removed and an 1/8" thick doubler runs across the entire width under the steel floor pan section. The front studs were also reinforced. We are adding clip-in harnesses so eyelets with reinforcement plates will go in for lap belt anchors as well as a solid mount for the anti-sub belt under the seat. Will show all of this next time.

                Tires Are Everything

                Its time to talk about the single most important aspect of this TTC build - the wheels and the TIRES.

                Tires are the most important aspect of a road race car. Let me repeat that for emphasis: Tires Are The Most Important Thing In Racing. The four tire contact patches are the only things connecting your car to the race track. Through these four little patches all of your forward accelerations, braking and cornering loads are generated. All of the work we do on the suspension is just to make sure the tires are happy - to make them stay flat, to always keep them in contact with the road, and to make sure loads are distributed as evenly to all 4 patches as possible.

                So with this car being based in TTC class with a 7 point penalty, that leaves us with only 12 points to work with (19 class points - 7 penalty). And while that gives us some options for lots of different mods (upgrading power, brakes, suspension, lightening the weight, aero and tires), we're going to burn almost all of our points on the tires. This is a very critical decision, so let me explain what we're doing. This decision was made after hours of internal debate, hundreds of permutations of width + compound (+ other non-tire mods), but mostly comes from years of racing experience and knowledge: Knowing that the tires are almost all that matter.

                TIRE WIDTH - As I pointed out in a previous post, everything you modify in the TT letter classes is either listed as a No Points Modification (which we are using every one we can!) or is assigned a number of points. It is all clearly stated in the TT rules. Tire width changes are "expensive", and the points in sizes increases above the "base class size" (TTC = 255mm) are shown below.
                • Equal to or greater than: 10mm +1, 20mm +4, 30mm +7, 40mm +10, 50mm +13, 60mm +16, 70mm +19, 80mm +22, 90mm +25, 100mm +28, 110mm +31, 120mm +34, etc.
                • Equal to or less than: -10mm -1, -20mm -4, -30mm -7, -40mm -10,

                Big Wheels Keep On Turning!

                As you can see you can get points BACK by going to a SMALLER tire as well. There is no other way in TT-Letter classes to gain points back, so this a big deal - and something we are going to do. Many will be surprised by this, as I've preached "BIGGER IS BETTER" for so many years. And while that is still true, we just don't have the points to go bigger, and feel that burning the points ALL on the compound makes more sense. Here's a comment from a corner-carvers reader and my reply:

                Originally posted by Nick C
                Will the rules let you put 335's on? 17x12" rims are a bolt on affair.

                Yes, it would is technically "legal" to run 335mm tires on a C4, but unfortunately the points just aren't there to do this and stay in TTC class. We're going to be running much narrower tires than that, but with what we feel is the right compound.

                These pictures are of Jason McCall's 1989 Corvette that is prepped for SCCA BSP class (and was the National Championship winning car in 2005). It runs 17x11" CCW wheels in front and 17x12" wheels out back with Hoosier A6s in 315mm up front and 335mm out back. The fit is pretty tight - it has custom flared front "fenders" (the hood) and has the little 1996 Grand Sport "export" flares out back to make these fit - and we can legally add flares for zero points.

                I've driven and ridden in this car and it is a GRIP MACHINE, just a big go-kart. Very fun, and the wide, sticky autocross compound tires he runs are why its so fast. And while I'd love to do this on our C4, the points for the compound (Hoosier A6 = +17 points and A7 = +22 points!) plus the increase in tire width (255->335 = +80mm = +22 points) would cost a whopping +44 points for just this tire upgrade. Using all of the points we have in TTC (19 - 7 = 12) and then even moving up to TTB (+20 more) we're still short by 12 points for a 335mm A7, so that tire choice would be a move straight to TT3. This is why we cannot use the tires we'd LIKE to use (I'd slap 335mm Hoosier A7 tires on this in an instant if the points allowed it!) but the compromise we have chosen will still work well enough - we suspect. Remember: Everything in racing is a compromise... and everything depends on everything else.

                Many of you that have experience with the C4 Corvette know that most of the later C4s came with a 275/40/17 tire on 17x9.5" wheels at all four corners, as did our 1992 Base Trim Model Corvette. But the TTC class "base tire" is 255mm, no matter what the OEMs put on the car. Wheel width is unrestricted, other than a track width change limit of +4 inches. Beyond that you take points. Our car has 285/40/17 old and crusty street tires on it right now, which would cost us (+30mm over 255) +7 points to use, but they are a joke. So hard they can spin freely through the first 3 gears. I won't be caught dead on a road course with old street tires, not even brand new 120-200 treadwear street tires (which are worth +2 points), unless the rules require that for everyone.

                After racing our TT3 car in various "street tire" events/series last year, and at some tracks we also ran with R-compound Hoosier A6s in other series, I know the true lap time value of sticky R-compound tires. Going from a 335mm BFGoodrich Rival to a 345mm Hoosier A6 is worth a MASSIVE amount of time. On a typical 2 minute road course that difference is 5-7+ seconds per lap with the Hoosier over a 200 treadwear tire, and the Hoosier is MUCH easier to drive. So we're gonna stick with what we KNOW works and that has a great NASA TT contingency program: Hoosier.

                TIRE COMPOUND - The compound of the tire is as important than width in Time Trial. Maybe even more important. Why? Because every TT lap is essentially run at a Qualifying lap pace, where you need to be pushing 10/10ths. To win you just need to set ONE fast lap per day (each day is a new competition), and waiting around for 3-4 laps for your "tires to warm up" will only get you mired up in traffic, as the front of the field catches the back end. There are a LOT of tire compounds listed and points assigned for each. The only "free" tire compound in TT-letter are those over 200 UTQG treadwear numbers. The tire models are grouped together with compound and performance parity, and the points given look to be pretty fair. There were massive adjustments made to these points for 2015, which was long overdue.
                • DOT-approved R-compound tires: BFG R1S, Goodyear Eagle RS AC (autocross), Hankook Z214 (C90 & C91 compound only), Hoosier A7, Hoosier Wet DOT (if used in dry conditions—see section 5.6) +22
                • DOT-approved R-compound tires: Hoosier A6 +17
                • DOT-approved R-compound tires and those with a UTQG treadwear rating of 40 or less not listed otherwise in these rules: BFG R1, Goodyear Eagle RS, Hankook Z214 (C71, C70, C51, C50), Hoosier R6 & R7 & SM7, Kumho V710 (note: Continental Tire Sportscar Challenge EC-Dry tires OK (225, 245, 275) +10
                • DOT-approved R-compound tires: Toyo Proxes RR, Hankook TD +7
                • DOT-approved R-compound tires and those with a UTQG treadwear rating of 50 to 130: Maxxis RC-1 (ex. Kumho V700, Michelin Pilot Sport Cup, Nitto NT01, Pirelli PZero Corsa, Toyo R888, Toyo RA-1, Yokahama A048, etc.) +6
                • (non-R-compound) tires with a UTQG treadwear rating of 120-200 (examples: BFG g-Force Rival, Bridgestone Potenza RE070, Dunlop Direzza Sport Z1 Star Spec, Hankook R-S3, Kumho Ecsta XS, Toyo R1R, Yokohama Advan A046 & Neova AD08,) +2
                • Non-DOT-approved racing slicks +30

                That is a dizzying array of compound choices and, when combined with the size choices, it makes for a lot of possibilities. But we've run the numbers using these compounds + various widths and have settled upon: 245/40/17 Hoosier R7. Not the softest tire but damned close. Not the widest tire but "wide enough" (and it gives us a point back). The tire choices are still very limited in the brand new Hoosier A7/R7 compounds, but this seems to fit the bill. The spec's on this particular 245mm tire look pretty dang good, and I'm hearing good things about the R7 compound in tests. Our first event will teach us a lot... either we guessed right or made a big mistake!

                These wheels are stupid light! We will weigh the wheels alone once the old 275 Hoosiers that came on them are dismounted

                WHEELS - We will run these Hoosiers initially on some 17x9.5" SSR wheels, which are both light and strong. Very light, in fact... around 15 pounds. Getting a set of these Corvette sized SSRs is like finding a wild unicorn - very rare and no longer made. SSR went out of business after the 2008 recession but it seems that they have reformed and are back - but not making a lot of the "big" sizes that fit Corvettes any longer. This set came from our shop manager Brad's former Super Stock 1994 Corvette, and he has two identical sets in perfect shape. I have dibs one set but the other is available. The Hoosier A6s on these wheels are DOT stamped from 2008! These wheels are perfect and have been sitting in his attic for almost 7 years.

                What's Next

                I could go on. And on. But I have probably bored you enough! Our crew is still busy at work finishing the prep on the Corvette for the first race and I'll try to do a quick update next week, right before we head down to MSR Houston Jan 16th. There's still a lot to do and not much time left...

                Terry Fair -
                2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
                EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


                • #9
                  Re: Vorshlag Budget TT Build: Project DANGER ZONE

                  Love the bibliography references! Too funny.


                  • #10
                    Re: Vorshlag Budget TT Build: Project DANGER ZONE

                    Project Update for January 16th, 2015: The first stage of "initial race prep" is completed and I'm going to try to write a QUICK update before we load up and I head down to Houston (in the next few minutes!) for the first NASA Texas event of 2015. We had a lot of parts delays but the crew at Vorshlag got everything on the "MUST HAVE" list completed. They only worked on this car over an 8 day period - due to other cars on the schedule. Big thanks go out to Olof, Ryan, Brad and Jon for all their hard work and long hours over the past week and a half. Thanks also to Jason and Tim for helping pick the mods and source the parts we used. Now all I have to do is drive the thing well... but I have a good back-up driver in Brian Matteucci, thankfully.

                    Brake Upgrade

                    The last week was a blur, as we had a lot going on in the shop with other customer cars, the phone rings off the hook in January (everyone waits until now to order parts for the new race season), and we're still gearing up for our new CNC machines - which has been a royal PITA. I had a birthday this week, and tons of other crap going on, and I usually work seven days a week playing catch-up on Vorshlag stuff on the weekends. But last weekend I stole a day away to swap on the front brakes.

                    Left: The 12" front brakes are adequate but can be upgraded to 13" rotors "for free" (no points). Right: The two rotors in question

                    So the 1992-1995 "Base Trim Model" Corvettes all came with these wimpy looking front brakes, shown above. These include the 12.0" diameter x .810" thick vented rotor and PBR twin piston aluminum caliper, which I detailed a bit in my Dec 29th build thread post (post #5 for most of the forums). And I hinted that we would be able to upgrade from the 12" to the 13" rotor set-up for "no points". Normally this is a +2 upgrade, and we only have 3 total points left to play with. I'm saving those for later so we pulled the trigger on the correct rotors, calipers and caliper brackets back on Dec 23rd.

                    The measured weights for the two front rotor sizes were pretty close to the spec sheets from Centric. Since nobody seems to want to work the last 2 weeks of a year in the USA, we didn't see these parts until late last week (around Jan 9th), and I started installing them on Saturday the 10th. The right front set-up went on fine, but I got bogged down cleaning the front suspension and wheel well...

                    It was worth it seeing the beautiful, forged aluminum uprights and control arms after 45 minutes of brake cleaner and WD-40 plus some elbow grease got 24 years of gunk and grease build-up off of the metal. Be careful with brake parts cleaner as it is pretty aggressive, but it cuts through the thick caked on grease well. Once I started to see metal underneath I switched to WD-40, and used WD-40 only on all of the plastics and rubber seals. Decades of road dirt wipes off after a little soak with WD.

                    Cleaning the gunk showed me a split ball joint boot, which we will replace in another round up upgrades later (along with all of the original, crusty rubber suspension bushings - which can be replaced with any non-metal bushings). The old bits came off easily enough and the new 13" rotor and longer caliper bracket went on. And yes, we gained a solid 7 pounds in the rotor upgrade, but its "good" weight. This is cast iron that can both soak up brake heat and more rotor area and vanes to help radiate brake heat. This car will be 3203 pounds with driver and ballast and that's a lot of mass to slow down for thin little 12" brakes at both ends.

                    The 2-piston sliding PBR calipers (3.56 pounds) are familiar to me, as I've used them on SN95 Mustang Cobras and 3rd gen 1LE/B4C Camaros in the past, as well as on my 94 Corvette - which had the Z07 package and these larger "J55" option 13" front brakes. The J55 calipers are wider, and the J55 caliper bracket (2.56 pounds) is longer, but neither is much heavier than the "base" brake parts.

                    How are we getting to use the "bigger" J55 brakes from the Z51/Z07/ZR1/GrandSport models without points? Well the trick is this: all 1996 Corvettes models came with the larger J55 brakes, including the base trim model. And the listing for the car we have (1992 Corvette) is listed as 1992-96 Corvette (non ZR1, non-LT4). So we're updating to the base trim level brakes for the 1996 model car, since the 1992-96 cars are listed on the same line (again, not the 1996 LT4 or Grand Sport). We can also play around with swaybars and springs from the 1996 base trim model cars, which we might do later. Here's the rule that makes it all happen...

                    Rule 8.5, page 41 of the TT ruleset for 2015:

                    Updating of parts between different model years of the same vehicle model is legal provided that the competing vehicle is both in the same model group listing (same line) in the Table in 8.2.2, and in the same generation of that vehicle model, and that the entire assembly is replaced. Backdating of parts between different model years of the same vehicle model is legal provided that the competing vehicle is both in the same generation and is in the same or higher base class. No interchange of parts between assemblies is permitted in order to create a new assembly.

                    Just like in SCCA Solo, this "update/backdate" rule can be exploited to your advantage. It takes a lot of research and sometimes rummaging in junkyards, but it is there as a tool for dedicated racers to use. It helps to have factory manuals as well, which we do (thanks to Matteucci).

                    Again, this is a simple bolt-on upgrade and we have to use OEM (or OEM equivalent) parts to make it legal. No 2-piece rotors, no aftermarket calipers, this is all real deal GM bits. The brackets are from GM and the calipers are rebuilt GM calipers. So getting the right front corner swapped to the J55 bits took less than half an hour. I added blue loctite to the caliper bracket bolts, torqued it all to spec, re-used the old brake hoses (we will make stainless lines when we have time) with new crush washers, installed new caliper retaining pin and E-clip, easy.

                    Then a friend stopped by the shop mid-day Saturday and convinced me to go see the Interview at the Alamo Draft House. The movie was hilarious and I'm glad I went, but it put me behind on the right front brakes. No worries, I'll do it Sunday.... nope! Amy made me go write the eBay ad for our TT3 prepped 2011 Mustang, which I did then started writing the massive OUSCI 2014 write-up, which I finished today and promptly deleted (it was too harsh).

                    So on Monday I came in and the guys were working on other items on the Corvette, so I got to work on the left front brake upgrade. As soon as I tried to put the left front caliper on, DOH! It didn't fit.

                    The box had the correct J55 caliper bracket (which moves the caliper out for the 1" larger diameter) but the wrong caliper casting. It was too narrow by almost .300" and would never fit over the thicker rotor (.300" thicker). Crap. We had ordered the right parts, and the part number on the box from Centric was correct, it just had the wrong damned part in it. Oh well, stuff happens. We took these pictures, sent them to Centric, let them kno how urgently we needed the right part, and hoped for the best.

                    Left: original Delco/Bilstein dampers. Right: New Bilstein OEM replacements went on

                    Luckily they got the right caliper to us just in the nick of time (Wednesday the 14th!). The OEM replacement shocks also arrived at the same time (also ordered in December and also very very late) and Olof and Brad got all of that installed when I was out running errands that day. We replaced factory base trim model "Delco Bilstein" dampers with the OEM replacement Bilsteins that were listed in our Bilstein dealer catalog. The two original rears were blown and the new bits matched up perfectly. These are non-adjustable and are considered replacement OEM dampers available, so they are a "zero point" install.

                    We re-used the Carbotech brake pads Matteucci had purchased for the OEM brakes, which were XP12 front and XP8 rear. A little soft for my tastes but they were brand new so we will use them for this first event. We pushed some Motul RBF600 through the lines and it felt good. Too many other fires to put out to get to brake cooling this time around so we'll keep an eye on the fluid and Alcon temp strips at this first event.

                    Tires and Wheels Installed

                    The Hoosiers arrived this week Olof dismounted the 7 year old crusty 275/40/17 A6 Hoosiers that were on Brad's 17x9.5" SSR wheels. Then he mounted the 245/40/17 Hoosier R7 tires and balanced them. They did all that while I was at lunch one day and I didn't get to weigh the wheels without any tires, so I'll have to do that next time, but I can do simple math. Just weighed an old 275 Hoosier that was removed (22.40 pounds) and the weight of the wheels+old tires (38.76 pounds) that puts the 17x9.5" ET55 SSR wheels at about 16.4 pounds each. Not too shabby.

                    The SSR wheels were a bit dirty so I cleaned 7 year old brake dust off of the inside barrel and spokes with more WD-40 and some elbow grease. The 245 R7 looks so tiny to me, after a season of using 345 A6 Hoosiers, but it doesn't look bad on the car.

                    We will see if burning 10 of our 13 class "mod points" on tire compound was worth it this weekend. This is an experiment that could pay off big or fail miserably.

                    Roll Bar, Harness, Seat and Fire Bottle Installed

                    With only 8 days of shop time we were not able to build a full roll cage (that will be a 3 week job by itself) but Olof did manage to get the roll bar built, reinforced, and mounted.

                    A big time suck on this job was making the aluminum cover plates. These are necessary on a fiberglass bodied car to cover the access holes in the body to the steel frame.

                    Again, on a traditional steel bodied/unibody chassis car this step is not necessary at all. But its a Corvette, and has to be a pain int he ass. Olof used card stock to make templates (below) that cover the access holes, then transferred this into .065" thick 3003 aluminum sheet.

                    The sheet was cut, bent and welded at the joints to make a box-like shape that fit the funky fiberglass tub shape and covered the openings with about a 1/2" overlap. Then a few holes were cut to add small stainless steel button head bolts and riv-nuts were added to the fiberglass (these are special ones we use just for fiberglass, with a different grip length than normal sheet metal riv-nuts)

                    A silicone bead was added to the perimeters of the fiberglass and these four, somewhat elaborate aluminum covers were then set in place and bolted down. These will now keep water, dirt and debris from spraying up from the tires and getting into the passenger cabin. Olof did a superb job and they look great and fit tight around the roll bare tubes. These can be removed and the roll bar unbolted for when we go back and finish the roll cage. Similar plates will be needed up front at the additional 2 lower points of the 6-point cage design.

                    We knew we were going to be WAY too light for the class minimum (3203 pounds) and would need anywhere from 90-200 pounds of ballast. On Tuesday we were getting a little tight on time so I asked Ryan to step away from a cage job he was working on and make the ballast weight bracket from some heavy 1x2" tubing. I was thinking of something basic but he made this beefy assembly with a slick, threaded top cap that fits over a 2" tube.

                    For ballast I purchased new 45 pound "olympic" style barbell plates with a 2" center hole. Typically cast steel weights like this cost around $1/pound, which is what I saw at a few places like WalMart. But after doing some shopping I found the best price at Academy sports, who had a wider assortment of better looking plates to choose from. These 45 pound plates were $31 each, or about $.68/pound. Sure, you can slum around on CraigsList and maybe find some mis-matched weights for around $.50/pound used, but its very hit or miss. Save yourself some hassles and go to Academy. If you want something more compact you can usually buy lead for $1/pound at plumbing supply stores, but just wear a mask when cutting or grinding on this stuff.

                    I didn't get any detail shots but the factory seat mounting studs (which are reinforced and rated for carrying up to 300 pound passengers) were used with some BIG bolts cut down on the lathe (and drilled/tapped to fit over the seat studs) go down from the top to secure the rack in place. You could pick the car up from this set-up and the 2" tube fits tight to the plates in sheer. At a minimum we will run 90 pounds of ballast here plus 120 pounds of fuel in the 20 gallon tank. Once we replace the 46 pound glass rear hatch with plexiglass we will add another 45 pound plate to the ballast box.

                    continued below
                    Last edited by Fair!; 01-16-2015, 11:59 AM.
                    Terry Fair -
                    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
                    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


                    • #11
                      Re: Vorshlag Budget TT Build: Project DANGER ZONE

                      continued from above

                      The factory seat mounts are reinforced with extra steel from the factory, but we added more. 1/8" thick steel plate wraps around the stock stuff and was stitch welded to the floor as well as wrapped around up into the tunnel and frame on the sides, where it is bolted or welded for more support. The harness anchors for the lap and anti-sub belts are from G-force. These eyelets allow the clip-in ends from a Cobra/Schroth 6-point Profi-2 harness to attach. These are my favorite harnesses and made by Schorth in Germany to FIA specs. This set has 2" upper shoulder straps to better work with he NecksGen HANS device I will be wearing this weekend.

                      As usual, any "pretty" pictures you see here were shot by shop manager Brad with his Canon gear. The rest of the pics are from my "potato-cam" Galaxy S4 camera phone or my Nikon D90, which I can't seem to use worth a damn. The shoulder harnesses were wrapped around the harness bar tube with the proper wrap technique as specified in the diagram on page 42 of the NASA CCR.

                      Last but not least, a 2.5 pound fire extinguisher was added. This is a small "Halotron" (Halon replacement) hand held fire bottle that can be used to put out small electrical, oil or grass fires and doesn't leave a big mess of dry chemical or foam residue behind. We add these things to every track build possible, even when they have a full fire "system" with multiple nozzles. No need to blow a big bottle when all you have is a little grass fire under the car after pulling off track into dry grass. We used the Drake quick release mount here, which we have used a half dozen times. CNC aluminum, roll bar or floor mounting with the same kit, and one pin can be pulled for fast bottle removal but it stays tight and rattle free when racing. Good stuff.

                      Weight Check!

                      Now you've seen how crazy I am about dropping weight and weighing everything in this and other build threads. Weight is the enemy! Lowering weight helps all acceleration vectors, be it braking, forward acceleration or lateral acceleration (cornering). We do a LOT to lower the weight on any race car build, and this car has gone from about 3300 pounds stock (we never weighed this car with the interior but that's what my 1994 Corvette weighed) down to about 2720 pounds. This weight drop was from lighter wheels, no interior, no passenger seat no side or rear glass, and no HVAC bits. The air conditioning compressor has been removed as have the headlights. The lighter wheels and tires help, too.

                      Left: 2841 pounds with fuel but no driver or ballast. Right: 3200 with driver, fuel and ballast

                      We have added about 60 pounds in the roll bar and about 120 pounds of fuel (its nearly full) and the heavier J55 brakes and it was sitting at 2841 pounds. That's a solid 700 pounds lighter than our TT3 Mustang was without ballast or driver! Sadly we have to weigh 3203 pounds with driver (or else we have to burn points to run lighter), so ballast went back in in the above right picture to get us there. The plexiglass hatch should help remove about 30-35 pounds out of the 46 pound OEM glass, but it might not arrive in time, so we will save that 3rd 45 pound plate for then.

                      Classing Sheets, Dyno Test and Custom Tune

                      So we haven't built "letter" class car for NASA TT or PT before, but have helped a number of people class their cars. The base classing + mod points thing is nothing new to us. Just like TT# (numbered) classes, the TTx (letter) classes have an adjusted power to weight ratio. In TT3 the class has a 9:1 ratio but we were able to get ours to 8.8:1 with the adjustments. Likewise, TTC's base 12:0 pounds per horsepower limit has some adjustments as well, namely with a smaller tire...

                      Using the 245mm tire has had so many benefits and this is just one more - we get a 0.8 ratio bump for this small tire. That might not seem like a lot, but when you are at 3203 pounds it is nearly 20 extra horsepower allowed...
                      • 3203 pounds / 12 = 266.9 whp (267 rounded up, in favor of the driver)
                      • 3203/11.2 = 285.98 whp (286 rounded up, in favor of the driver)

                      Which is a good thing, as it was going to be hard to only make 267 whp even with a dead stock engine, manifolds, cats and muffler. We had the car over at True Street Motorsports yesterday and they were able to coax 284 whp and 331 wtq out of this 24 year old, bone stock iron block LT1, through the stock cats, manifolds and exhaust. Not too shabby. It even sounds better after the tune.

                      Above: Video of the stock LT1 motor at idle and revving, after the dyno test.

                      We have our dyno plot and classing sheet attached below. As you can see we've started with TTC + 7 penalty points, which left us with 12 points to play with. We got one back for running 245mm tires (-10mm below base class tire) for 13 points total. We burned 10 on the Hoosier R7 and still have 3 points to play with. We will be very stingy how we spend those this season, so stay tuned to see what we invest these points in to make Danger Zone faster.

                      Left: The SAE corrected dyno plot making 284 whp. Right: TTC classing sheet with points

                      Last Minute Tweaks and Fluids

                      The Moroso oil pan for this motor is huge and the motor now holds 8.5 quarts of Mobil 1 synthetic oil (15W50 is my preferred weight for track cars), with a fresh Wix oil filter. Olof went over the car and filled out a NASA tech form but we still need to get a Logbook issued for the car at the event, so the plan is to leave Dallas early and make the 4.5 hour trek to south Houston on Firday and get there before dark. Then I can set-up the trailer, unhook, unload the C4, get the logbook tech and weighing, and make sure we have our ballast set correctly.

                      I couldn't leave the massive openings in the hood where the pop-up headlights used to be so I asked Olof to make some aluminum brackets to bolt to the inner hood structure and to the existing holes in the headlight covers. Those went on and now forms a fairly seamless clamshell hood surface. The front turn signal and corner light assemblies were also reinstalled to fill holes. We will go back and make flush mounted aluminum covers later, when we have the time.

                      Brad jumped into the Danger Zone this week as well and did a lot of wiring and some light fab work to the Corvette. He used to race a C4 himself and knows the car all too well. The wired AMB transponder from our TT3 car was moved to the C4 and Brad made some brackets for that, wired it up to a lighted switch (sometimes its handy to turn off the transponder - if we want to make another entry in the same car with the 2nd battery powered transponder we have). He also got the rear brake lights to work, after repairing some cut wires.

                      He made an aluminum panel to mount the switch in the center dash area as well as the 3-port "power panel" shown above. This was a cheap purchase which arrived in only a few days for $31 shipped. This panel has waterproof covers over a 12 Volt cigarette lighter port, a volt meter and a stack with dual 5 Volt USB ports (one a high amp and the other a low amp draw - see detail image above). Very slick little package that should prove handy when it powers my onboard vidcam and AiM SOLO timer. I will report back with how well this worked, or not.

                      The formed, lightweight, plexiglass rear hatch we ordered a week and a half ago arrived this morning so there's no time to fit it, so we reinstalled the OEM back glass. Order Desk Manager Jon wrapped the "ugly" mis-matched door with white vinyl. He also designed, cut and mounted graphics for our logos, "DANGER ZONE", Hoosier and Bilstein decals, and some class/number decals for all sides of the car.

                      Its time to load up so I didn't get the final pics... tune in next week for the post race update to see the final look, or look for it on Facebook with this hashtag #DANGERZONE.

                      What's Next?

                      The only thing on my RADAR right now, outside of cutting metal next week on our new CNC machines (tooling is FINALLY here!), is the race this weekend at MSR Houston. I will be paddocked with Costas, Matt White and other friends probably near Turns 16-17.

                      We are running MSR-H in the Clockwise direction this time (they alternate the direction for NASA events every other year), so I haven't run this track layout since 2013. The video above shows the lap record I managed in the TT3 car 2 years ago, on the skinny 315 tires. The lap record for TTC is currently a 1:50 but I think we might be able to manage a 1:46 if everything manages to stay together on the car...


                      We have a pretty crazy class lined up: Our 92 Corvette, a 2003 Mini Cooper S (fully race prepped) and a 2005 Mazda RX8 (fully race prepped). Talk about an odd mix... and we will once again be the heaviest yet most powerful car in class, just like we were in TT3. I will post up more details after this weekends race. Until then...

                      Terry Fair -
                      2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
                      EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


                      • #12
                        Re: Vorshlag Budget TT Build: Project DANGER ZONE

                        Project Update for January 26th, 2015: Our first race for Project DangerZone has passed and this is my "post-race report" along with some analysis of what went right and wrong.

                        I Need To Apologize for Trash Talking? Really?

                        Before I get into our first event results or talk about what we're doing to this car next I think I need to address some of my "pre-race performance speculation", aka: TRASH TALKING. Some say it was unnecessary or disrespectful, but it was done mostly in jest. Getting people to notice our projects takes some extra effort when its a 24 year old ghetto jet, so I took a gamble and "bench raced" my way to some predicted wins and track records. Where's the harm in that?

                        This was how the car looked right before we loaded up to tow to Houston, sans NASA decals

                        This sport isn't an "everyone gets a trophy" kind of competition. There are winners and there are losers - that's kind of the whole point. Sure, racing is still fun when you lose, but winning is more funner. Since when do racers need to apologize for a little harmless trash talking? To those that were offended by any of that in my previous posts, all I have to say is "that's part of racing". If I chose to I talk up this project a bit and had it flopped the first time out, I would have looked like an idiot and had to eat some crow. That was the risk on my part, but this whole build is a calculated risk...

                        The Gamble: An Old Car And A New Tire

                        Building this 24 year old car into my primary race car for 2015 is a big risk, as it didn't really fit into the "typical cars we work on here". I've picked the wrong horse a few times but normally we can look at a rule book and class listings and see several underdogs that have unseen potential.

                        But honestly, this car isn't magic. We could have picked a number of other low cost cars that could do very well in this class (TTC), like an E36 M3 or an S2000, both of which are proven winners in TTC at the highest levels. The point of this build wasn't to find the End All Be All car, but to show that as long as the classing is equal the car you choose doesn't matter as much as how it is prepped and driven.

                        Am I saying the class could be won with any of these cars? Yes, I am. This 1992 Corvette isn't some super ringer, and we've prepped/won with both S2000s and M3s in this very class, with our own cars and customers' builds. Anyone can win if they start with a fairly classed car, prep the car to the limits of the class, test their set-up to maximize performance, use the best tires available (*tires are the biggest factor in any build!) and drive it well.

                        Another reason why we chose this car (other than it was a sweet deal that fell into my lap at the perfect time) was to show some variety for our business here at Vorshlag. We have unfortunately become "known" for BMWs and Mustangs and Subarus, but the reality is we work on anything that can be classed for road course, autocross, rally or other racing uses: new and old, Domestic, Asian, and German, you name it. People didn't "know us" for Corvettes but we have owned, raced and worked on a lot of them, and use the drive trains from Corvettes in a number of V8 swaps for all sorts of chassis. Having owned this same model Corvette in the past I knew it has potential to handle, brake and accelerate well. To me this C4 was a fairly safe bet, but the fact that it was a 24 year old car made for the biggest gamble. Any number of "old-car" things could have failed at the first event and shut down the weekend before the car ever turned a lap.

                        Left: The R7 tires were new when we got to the event. Right: After a race weekend with 5 sessions and 3 drivers - tires look great!

                        The tire was another unknown - the Hoosier R7 was relatively new and we had zero experience with it (I ran the 2013-14 seasons on the A6 in much larger sizes). We also chose to go with a narrow tire width (since there weren't many R7 sizes to choose from yet, as more sizes are being rolled out as the R6 sells out of inventory). Would a 3200 pound car be able to survive on a 245mm tire? It was another gamble. If the tire didn't hold up, we would have to revisit our choices.

                        Some folks sent me links to this build thread discussed online and apparently a few racers were upset that a "big money shop" was coming into the "grassroots" TT letter classes and bringing a purpose built race car against their TT cars they drive to the track. To them I say: the NASA TT rules don't have any wording about this set of classes being for daily driven cars, and in fact the TT division shares the same rules as NASA Performance Tuning - which is for wheel to wheel racing cars - just without the safety regs. We already see PT cars running in TT all the time, because the contingency is good and the PTB-PTF classes are direct crossovers to the TTB-TTF classes. The same holds true for TTU/1/2/3 and SU/ST1/2/3. Time Trial is a haven for race cars but also allows cars without full safety gear to enter.

                        As for this being a "big money build", that is hilarious and absolutely not what we have done here. This was a last minute option, "Plan B", eight day long race car build - that isn't finished. We had no other car ready for 2015 season, this deal fell into my lap, from a friend who I had brain stormed this car build with three years earlier, and I took this gamble - to have something to race. We have about $5000 dollars in parts/car purchase and about 60 hours of shop work (we log all jobs to the 1/100th of an hour) in this build so far. We worked on this car between regular customer jobs and only spent 8 days actually working on it, but it held together for the first race weekend (barely). We spent our time almost completely on the safety aspects the car needed and left everything else stock for this first event.

                        If the "speculative talk" in my first few posts here have people fired up to come join us in TTC - that's good! I'm hoping people look at how little money this car costs to buy and prep, how it has proven itself already, and "get the bug" to build a car for NASA Time Trial letter classes or Performance Tuning! This set of classes allows a lot of freedom to choose what you want want to concentrate on: suspension, tires, horsepower, aero. The rules are structured to limit your overall mods which in turn does limit your spending. Its a great series and I encourage people to look at the TT rules/PT rulesets, check out the car "base classing", and start hitting CraigsList looking for something fun to start with. It doesn't need to be a brand new car or an expensive car - look at the past and see how some of the best cars from the last 2-3 decades are classed.

                        As you may remember, I had proclaimed we could win TTC with this car its first time out, reset the lap record, and even predicted some bold lap times for our first event at MSR-H (1:46 clockwise). So, how did it all play out at our first NASA race weekend? Do I look like a stooge talking out of my hat, or was our guess work correct and did we prep the car in the limited time available in the right areas?

                        NASA at MSR-Houston, Jan 17-18th, 2015 - The Debut Event!

                        The old TTC lap record was a 1:50 here was set in 2013, which I showed in my last post on the Friday before the race. I had predicted a lap time of 1:46 but had privately hoped for a 1:45 lap. Let's back up to where I left off in my last post and get caught up on this debut weekend of racing for Project #DANGERZONE.

                        Friday January 16th, 2015 - Unloading and Tech

                        After Jon finished installing the decals and I fired off my pre-race forum post, we loaded the trailer and I left Dallas a little late, at about 12 noon - wanted to leave at 10 am. Took me a little over 5 hours to tow 300 miles to the south end of Houston, where MSR-H is located. Google maps has gotten better of late and it re-routed me around 3 construction zones or crashes, on a goofy route, but I never had to stop. It would re-route me on the fly, ask me to verify, then I'd go... which was nice. I got to the track at about 5:30 pm, at dusk, and Costas had a paddock area set-up with his trailer plus both of Matt's trailers. It was pretty far from grid so we did a lot of walking back and forth all weekend. We squeezed my trailer in near Turn 17 and I unloaded the Corvette and rushed to tech as the sun dropped.

                        The tech guys got me in fairly quickly, right as it was getting dark, and they went over the car with a fine toothed comb. The only thing they could find were the side post battery terminals were uncovered... now normally I'd agree that a top post battery ALWAYS needs plastic around the terminals in case something gets dropped on them, but these were buried on the side and covered by the fiberglass body. Some duct tape and I was legal for this event. I will add the rubber terminal covers soon.

                        Any time you have a new car teched for NASA Club Racing classes or NASA Time Trial for the first time you have to get a NASA Log Book and a NASA annual tech sticker. The log book cost me $20 and the annual tech decal cost me $10. From here on it would only need the annual $10 decal, as the Log book is good for the life of the car. We're working with NASA to be able to issue log books here at Vorshlag, which should happen soon.

                        They didn't have the scales set-up Friday night, due to a mix-up with the ramps, so I left the ballast in the car a bit on the heavy side (about 25 pounds over by my calculation) and figured I would weigh the car in the morning before we went out on track. Nobody likes to get a surprise weighing and end up underweight, so I ALWAYS try to weigh the car at the track on Friday or Saturday to make sure our scale numbers match up with their scales.

                        Reloaded the car back in the trailer, said hi to everyone hanging out, and shared half of a pizza, which I scarfed down on my way to Matteucci's at 7 pm. Crashed out at his place and dreamed of this track layout all night...

                        Saturday January 17th, 2015 - Race Day 1

                        I hastily made the TT map (below) for Motorsports Ranch Houston (MSR-H) right before leaving town Friday, which shows not only the track layout and direction we'd be running this weekend but also two special cues for the TT group. First is the "Bunch Up" line, which is between Turns T7 and T6. On the out lap in each session TT drivers can drive somewhat erratically to scrub tires and warm brakes from Pit Out to this line. When cars approach the Bunch Up line they need to quit screwing around and form a single file line with tight spacing. This is done to keep the field from getting spread out and hopefully prevent the front of the field from catching the tail.

                        The second line to note for the out lap is the "Go Green" line, where the leader of the pack should get up to speed, this time so the field isn't bunched up too tight going into the first braking zone. Starting to go green too LATE only keeps the field bunched up on the first hot lap, usually making that lap slower than it should be for everyone. The TT field should be gridded fastest to slowest, in that order, and this order changes all weekend if a driver goes faster (but not if they go slower).

                        We had our TT meeting at 8 am Saturday right before our first TT session, called "TT Warm Up" scheduled at 8:45 am Saturday morning. In the meeting we met all the new TT drivers, talked about safety aspects, and went over two areas that will be policed as "out of bounds" and counted as a 4 off if the driver is caught with 4 wheels past outside curbing in two spots that are paved beyond the track limits. Its a long story but there's a shortcut going CW at Turn 1 if you drive inside a curb and knock over the cones they have there to separate the Pit In lane. Another area is between T16 and T17. Each Race Director (RD) makes these decisions and declares out of bounds for each Race Group. Our RD for Time Trial is Richard Wootten.

                        Saturday's "TT Warm Up" is a unique TT session for the entire weekend. We grid ourselves by guesswork (since nobody has any lap times yet) and then the times from this session are what are used to grid the field for the first "real" TT session, TT session 1. Times from the TT warm up do not count for competition, but gridding well is important. Lastly, Saturday counts as a separate competition from Sunday, and each day we have 3-5 sessions to get our best single lap time in. The goal is to have the best lap time in class, and a first place finish in a given day nets you 100 points for the regional championship. Hopefully you win your class with enough competitors entered to score contingencies. The only one I care about is tires: to win Hoosiers you need 5 in class per day to score 2 tires for 1st place. With 7 in class they will additionally pay 1 tire to 2nd place. That's assuming the 1st and 2nd place drivers are signed up ahead of time with the Hoosier contingency program, and run Hoosier tires and decals all weekend.

                        Left: The R7 looks good after the first session. Right: The hope is to buy the first set and win 4 more each weekend...?

                        I got to grid fairly early at Warm Up and slotted in about 8th in line, behind Alan Page's TTB prepped E46 M3. Alan is a customer we know from previous work we've done to his car and he's also fast, with several wins and track records to his name. He was shooting for the TTB track record, set 2 years prior by another E46 TTB racer KenO. A lot has changed in the last 2 years, both to the prep level of cars in NASA Texas as well as the track and that day's conditions. Two years ago was COLD yet all of the old MSR-Houston CW records were set that year. We felt like many TT records would fall at this event, especially the TTC record of 1:50.534.

                        Video of first laps ever in DANGERZONE - the Saturday TT Warm Up session

                        If you watch the video above you will see me learning to drive this car while taking it easy on a new set-up. Before that session I had never driven the car more than 100 feet. I guess I know MSR-H fairly well, having driven it maybe 5 previous weekends in the past 6-7 years, but its by no means an easy track. It is also run in both directions and the two courses are quite different, and I think I've done this config 2 or 3 times. The 2.38 mile course was run ClockWise this weekend.

                        So I went out in the Warm-up and tried to follow Allan's TTB E46 M3, who had been there testing on Friday and was dialed in. He was also wearing his fancy newly painted helmet livery! He was on a sticker set of 245mm Hoosier R7s so I figured our grip levels would be similar, but his power-to-weight ratio should exceed ours so he'd probably pull away from me - which he did. Luckily I gridded early and got ahead of most of the field, including the other three TTC cars.

                        continued below
                        Last edited by Fair!; 01-26-2015, 07:06 PM.
                        Terry Fair -
                        2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
                        EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


                        • #13
                          Re: Vorshlag Budget TT Build: Project DANGER ZONE

                          continued from above

                          The other TTC cars included BJ Mayer's 2003 Mini Cooper S, from Clown Shoe Motorsports, above. This was his beefed, up daily driven, TTC car's debut. It has a better power to weight ratio due to the 205mm tire he runs (>245mm tire = +0.8 ) as well as it being FWD (+1.0), for an unadjusted ratio of (12.0 - 0.8 - 1.0) of 10.2:1 pounds per whp. This car had GAZ coilovers, Vorshlag camber plates, a header/exhaust, supercharger and engine engine mods to help it make more power. I think his race weight was 2550 pounds or so? He told me but I forgot. He was on the SpecMiata tire, which is a 205mm "SM7" Hoosier (essentially an R7).

                          The TTC regular for the Texas Region was Herberto Ferrer in his 2005 RX8. This car is pretty well prepped and he runs the Hankook R-compound race tire, but I am unsure of the rest of his mods. This is a dedicated race car, though, and he is at almost all of the NASA Texas events running TTC. We also had Bryan Leinart who brought his CMC 4th gen Camaro into TTC for two sessions (Warm up and TT session 1) on Saturday and Sunday.

                          The ugly side of the Corvette. We're working on it.

                          I took my first two laps pretty easy in the TT Warm-up and tried to follow Allan, as planned. I was still feeling out the car, shift points, brakes, and tires when I botched a downshift going from 5th to 4th into the Courusel, T2, on hot lap 2. Instead of grabbing 4th as I had hoped it went into 6th, but I didn't realize that for a few hundred yards. The motor made all sorts of grumbling noises and had ZERO power. I coasted for about 400 yards around the long 270° corner dubbed the Carousel (Turn 1) and even past the start finish line. I had seen a 1:49 on predictive timing flash by on that lap, but with the long period of coasting it made for only a 1:50.692 lap. I finally figured out what happened by T17, downshifted into 3rd and set-up for another hot lap. Then I caught the back of the field pretty quickly and started smelling some oil smoke, so I came in early.

                          What I had found when I went into 6th was what the engine tuner warned me about - there's a massive dead spot in the engine between 2000-2200 rpms. Nothing happens - it makes no power. This makes the car drive poorly at these low RPMs, as when you hit 2000 it wants to die. So I made a note to keep the revs above that range, even on the warm-up and cool down laps, and it didn't happen again all weekend. Kind of freaked me out when it happened, though. "Old car stuff"... probably a worn out sensor or something, but the 1992-only engine computer is really limited and hard to diagnose issues with.

                          Once I came in I went back to my paddock spot and Matteucci and I looked at the smoking issue. Just as he had warned me it was the rear main seal leaking. He had already replaced the RMS once, so I figured it had to be something else. After power washing the bottom of the car to clean all the oil residue off, it never leaked another drop when idling at the shop... but after a few hot laps on track it was clearly a leaking RMS. After we let the car cool for 20 minutes with the hood up we moved the car to get it in the air, and the oil spot (see above) was the extent of the puddle. Not much, about the size of my hand, but every drop that leaks out while driving on course hits the exhaust 4 inches away and made for a SMOKE screen. Luckily this only started after two hot laps.

                          Times from TT Warm-up - I was in 4th out of 4 in TTC!

                          I thought we would be sitting up front of the class, even with the 1:50 time, but that was wrong - I was in LAST PLACE out of 4, ouch! I quickly got some text messages from people who weren't at the event asking me why I was so slow, hehe. It's easy to armchair quarterback something when you are hundreds of miles away. The fastest TTC car was the CMC Camaro (1:48.069), followed by BJ's Mini (1:49.768 lap), then Herberto's RX8 (1:50.324) then my coasting time of 1:50.692 bringing up the rear. I suspect my first session times may have lulled some folks into thinking we'd be eating dust all day, but I honestly wasn't worried. Much.

                          So Matteucci and I got the car in the air on two jack stands and I crawled underneath to clean off the accumulation of engine oil, which wasn't much. A bit of brake parts cleaning and some blue shop paper towel and it was spotless underneath after 5 minutes. It wouldn't drip once the engine cooled off, but this was also wasn't something we could properly fix track side. The RMS repair would require removing the transmission, clutch and flywheel back at the shop. Once all that is out we could then assess the issue and probably install a "seal saver kit" for what is likely a ring scored around the back of the crank.

                          We went over the rest of the car and it all looked great - including tire wear (perfect) and oil level (still totally full). Brakes felt a little spongy but not enough to bleed yet. Warm tire pressures were 34-35 psi, which is right where the Hoosier A7/R7 "Tire Care Tips" article said to shoot for. After I noted that I had a bit of syncho "snick" going onto 5th gear, Brian adjusted the clutch pedal travel stop that he built, moving it a hair to allow for more clutch dis-engagement. These 3-plate clutches are tricky to set-up and a bit of a chore in the pits... I stalled it a few times until I got the hang of it. The release range is VERY narrow and with almost no flywheel mass the motor has less momentum - making it easy to stall at low speeds. But once at speed? Oh, yea it was worth it! You actually have to shift pretty quickly to allow the revs to match, otherwise the engine slows down too much and lurches even on upshifts.

                          After checking multiple times that day the NASA scales were still not operational and we were told they would be down for the rest of the day. Knowing that we could have pulled all the ballast out but that would have been a douche move, so we left it all in and even topped the fuel tank off after each session, to keep the tank full and to count on the 120 pounds of fuel ballast. Limiting our runs to 2 hot laps, plus the out- and in-laps, the car was using 1.5 gallons of 93 octane gasoline per session. This was good to know since we were using extra fuel as ballast. I always wanted to be ready if the scales suddenly became operational - weighing under your declared minimum weight (3203) will DSQ the times from the session you just ran, as does a 4-wheel off or spin on course.

                          Matteucci was signed off for his TT license, since he had extensive SCCA club racing experience. Our "tactical plan" at the start of the day was that I would drive the first two sessions and he would drive the last two. But with the oil leak he declined to drive at all, and I changed my own plans to only take one or two hot laps per session, thereafter. The weather during the warm-up session was cold and I knew the track would get quicker once the sun beat down on the asphalt a bit, so I got geared up for the second TT session of the day, "TT Session 1", which I had hoped would also be my last for Saturday.

                          Just part of the 32 car Saturday TT grid, lined up for session 2

                          I was 12th on grid, right behind BJ's Mini, and was anxious to knock out a better lap. I still felt that the 1:46 lap I predicted was possible, I just needed to put it together and avoid any mistakes. I left a pretty big gap to BJ on the out-lap and didn't do any tire scrubbing. The R7s don't need any warming on this car, and they just work. I really REALLY like this compound and I am glad we made this choice. They wear well and grip was well past 1.2g lateral, in the data logging. Dyson Pham had something like 22 heat cycles on his R7s and still won TT3 on Sunday.

                          Went out and the first lap was a 1:47 and gobbling up the gap to BJ pretty hard. I went ahead and took a second hot lap and finally nailed the speed into and out of the big Carousel, which plays a big part in any lap at MSR-H. The speedo was showing 110 mph at the "Launch" (T13-14), 119 mph entering T6 on the back straight, and 113 mph entering the Carousel (T2) and 86 mph though that crucial turn. When I saw the AiM SOLO show my second lap at a 1:44.956 I knew that had reset the old lap record by nearly 6 seconds, so I took a cool down and came in.... with the biggest smile on my face in months.

                          Saturday TT Results:

                          After seeing the times from that session I noted that our car was the 7th quickest TT car out of 32 entrants so far. But then I noticed we only had 4 in class, so I went looking for a TT driver and instructor who hadn't run TT yet that day. Once you declare a class you have to stay there for the rest of the day. An old college friend Chris Ramey had been having fun in his TT1 Corvette on street tires, running in HPDE4 that morning, and jumped at the chance to take a ride into the #DANGERZONE! Ramey owns 4 Corvettes at the moment, including a C6 Z06, a C5 Z06, an '87 Z51 C4 and a Callaway Twin Turbo C4. Our TTC prepped C4 would be one of the slowest cars he had driven in a while, heh.

                          After getting the car reset to drive (jack up, clean oil, etc) and adding his registration as 192 TTC, attaching my second (battery powered) AMB transponder to the car and switched off the primary AMB, we had our 5th unique TTC entry. He strapped into the car and asked me what the target lap was. I knew Chris would be fast, and he has a tendency to go "Faster than you'd expect" so I told him to run a 1:46 lap. And asked him to only take one lap, due to the smoke. He got to grid for the 3rd TT session of the day and promptly put in a 1:46.165 time on his first and only lap, watching the AiM SOLO predictive timer closely. Normally I'd have told him to go for broke but he wasn't signed up with Hoosier contingency and I was, so we held him back... Chris told me he felt a 1:43 was possible. Yikes!

                          End of day Saturday TT Results - #DANGERZONE takes P1 and P2!

                          The rest of the TTC class didn't get much faster and the sun went behind the clouds right after that session, which cooled the track down. I felt fairly confident that the times would slow down in the 4th session and we sat out the last chance to put in a lap that day. That always makes me nervous but the cooler temps did indeed slow everyone down and my one timed hot lap for the day was enough to win the class, and Ramey's handicapped lap was still good enough for 2nd. BJ and Herberto got quicker after the Warm-Up and beat the fastest entry from that session, the CMC Camaro of Leinart, and every single TTC entry that day clobbered the old class track record.

                          The TTC win with 5 entries netted us 2 tires from Hoosier and 100 points for the regional championship. The Mini's time was still pretty close to Ramey's but about 1.4 seconds back from my time, so we were definitely keeping an eye on the Mini and the RX8 for Sunday. Anything could happen tomorrow, which was a whole new race.

                          After Ramey's lap was done we got the car cooled off, up on jack stands, cleaned up the oil residue again, then bled the brakes (in the strange order you are supposed to on a C4) with some RBF600 and rotated the tires. We didn't need to do that last bit, but it didn't hurt and took no extra work. Chris had complained of a long brake pedal and he was right - the pedal felt like mush. Bleeding it didn't help much so it was something we'd have to keep an eye on all weekend and address back at the shop. The fluid looked perfect and the 4 corner bleed produced zero bubbles. Hmm. Matteucci found some RTV and pookie'd up the bottom of the bellhousing, hopefully slowing down the smoke - he was covered in black RTV when he was done, though.

                          Left: The smoke looked like this after 2 laps, time to come in or risk a black flag. Right: Sunset Saturday at MSR-H

                          Very happy with the first result considering how little we did to the car. The tire wear was phenomenal even with only -2° front/-2.5° rear camber. Toe was 1/8" out up front and 1/8" toe in rear - Matteucci had strung the car himself and we left the alignment alone. The 34-35 psi pressures worked perfectly. The car was neutral if a bit loose, which is just how I like it. The brakes were far from perfect but replacing the 24 year old rubber brake lines might make a huge improvement, as would some real brake cooling (there just wasn't time).

                          The regular Saturday NASA party was great, with excellent bar-b-q and beer, trophies for the class winners, and pictures for the NASA newsletter. Dozens of people asked about the build and were amazed at the 1:44 lap time,and we had dozens more stop by the paddock both days wanting to see the car and admitting that they followed this build thread. After we had our fill of food we went back to the VERY dark paddock to load the car in the trailer... the trailer door was blocked. Hmm, car has no windows and I couldn't find anyone. After we left I texted Paul Costas and he added a blanket to the car to keep moisture/dew out - which we dubbed his "woobie". It looked hilarious the next morning, for sure.

                          Sunday January 18th, 2015 - Race Day 2

                          Costas' woobie kept project #DANGERZONE warm and dry, hehehe

                          Matteucci was going to work on his C5 Z06 all day so I was on my own for Sunday, but Jaaon Toth planned to help me with the car in the paddock, plus he took a bunch of pics with my camera. I got to the track by 7:30 am, had tons of time, so I ran down to Buc-cee's and got breakfast burritos for everyone in our paddock area, a giant bag of ice for the coolers and filled up the F-350 with diesel. Was back by 8 am with the first session scheduled for 8:50 am.

                          Left: TT3 racer Joshua Garcia brought his Toyota 1UZ V8 swapped AE86 and had a blast. Right: An E46 330Ci which used to be mine

                          Figuring the first session would be cold again, and still needing an extra TTC entry, I asked TT driver/instructor Jason Toth to take the first session in the Corvette as TTC 192. Since Sunday and Saturday are separate races, using the same number as Ramey did the day before isn't a conflict. We strapped the extra transponder back on and he got to grid for the chilly first session. I was again hoping the same cars from Saturday would enter and give us five in TTC so the winner would get two tires, whoever that might be.

                          continued below
                          Last edited by Fair!; 01-26-2015, 12:32 PM.
                          Terry Fair -
                          2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
                          EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


                          • #14
                            Re: Vorshlag Budget TT Build: Project DANGER ZONE

                            continued from above

                            Jason's lap was a bit compromised due to a TT3 car that spun right in front of him on his first and only hot lap, shown above. He backed off but drove through the smoke and took a sedate lap, putting one in the books and keeping out of trouble. He said he felt a bit rusty and jumping into a strange car with such a crazy clutch was a challenge. I appreciate the effort and it would probably only take a few laps for him to be right there on times, as I've raced with him for many years.

                            As the temps rose it started to smoke and it was dripping a bit when Toth went to the scales. The tech guys wanted to see the car again before we went back out so I took the car back to paddock, did the raise/clean/reseal trick after the car had cooled off. Once it was back to tech it wasn't leaking a drop and they cleared me for laps once again.

                            At this point I wanted to only take one lap and head home. A headache was starting (probably from sniffing brake parts cleaner for two days!) and looking at the weather it seemed that session 2 on Sunday might be the "golden session" where the best lap times of the weekend would end up. Got up to 70 degrees in the afternoon but was still low 60s for session 2.

                            Allan Page had run a 1:41.013 for a new TTB record in the morning but he also felt like session 2 would be faster. We weren't scheduled to go out until after 11 am, so we had a long break to reset the car. Meanwhile the sun did come out and warmed up the track. I got the transponders swapped back, got my suit and gear on, and went to grid sitting in P8 overall for this session, ahead of the rest of the TTC field and even some TT3 cars.

                            I was going to be putting in ONE hot lap, for the day, and it needed to be as perfect as possible. The goal was to go fast enough to ensure no other entries could touch the lap time for the rest of the day, so I could leave early with a little confidence. Ramey had predicted a 1:43 the day before but with the spongy brakes I wasn't sure. After frantically searching I realized that BJ had left Saturday night, apparently with a broken exhaust header. That left us with just 4 in class - Oh well, whoever won TTC today wasn't going to win any Hoosiers.

                            In the video above from this session you can see that the front of the field was really slow to take the green flag on the out lap and it bunched up the whole field badly on the straight before the Carousel. I was behind Dyson's TTB S2000 (running light and racing in TT3 for the day, trying to beat my old TT3 lap record and win that class). I wasn't sure about his power levels or times, other than he was gridded ahead of me so he had to be running quicker. Still, I backed off a bit on the run up to the Carousel.

                            Sunday TT Results:

                            I had talked with the TT3 driver gridded behind me, telling him I was going to be taking ONE hot lap than I'd get out of his way. But he saw me back off of the S2000 on the out lap and passed me. Technically we're not supposed to pass on the out lap (double yellow) but it wasn't a big deal... other than I had to back off a lot into that turn before we began the hot lap. I tried to gap him enough to avoid this, but as we took the start/finish I was gaining on him and had to brake early into T17. Crap, I figured my lap was ruined, but then he nearly spun off track in T16. He had some spin issues that weekend and I was ready for that. Once he got it straightened up he was way off line and I snuck inside him with a clean pass and got on with my lap. I probably lost only a half second there, at worst.

                            That lap was great and the car felt hooked up everywhere. I still had plenty of driving mistakes like early braking into "the Launch" and probably the T6 corner off the back straight as well, but it was still my quickest lap of the weekend. As I came around for the start/finish on this first hot lap I felt like it would match Saturday's time but instead it was a solid 1.2 seconds faster with a 1:43.733. Booya! Thinking the pass slowed me down I took a second lap but it was slower at a 1:44.3. I didn't try to push my luck with a black flag for smoke so I backed off after that and came into the pits. Wootten was watching and sent me to the scales, warning me that this entry was under "special scrutiny" from the National level and if I was light my times would get bounced (which is normal).

                            Before my session (at left) and afterwards (at right) in Impound, where I was scaled

                            I wasn't worried and just as expected I was 25 pounds over our minimum weight of 3203 pounds at 3228. That's exactly what I was shooting for - a big, safe margin of 25 pounds for this first event. For my first time to scales all weekend I was damned happy that our weighing and ballast had been perfectly in line on our scales as on NASA's. With constant fuel top offs after each session, this means we can run a good 15 pounds lighter next time (I'll always leave a 10 pound safety buffer over our minimum weight, at least).

                            After I got back to paddock and changed into my street clothes I let the car cool down and then looked at the results and decided to skip the last two sessions. I still had that pounding headache and a 5 hour drive home to look forward to, so I started loading up the trailer. When the car was cool enough I drove it inside (which itself was a huge win!) and strapped it down, then said some goodbyes and hit the road. With a pair of wins, a track record reset by 7 seconds, two tires won on Saturday (only 4 in class Sunday means no tires were available), 200 points towards the class for the regional championship, and knowing that I was able to back up the smack talk. Whew, what a relief!

                            Allan ran his best lap of the weekend in his E46 M3 and reset the TTB record to a 1:40.805, which was almost exactly 3 seconds quicker than my new TTC record. The overall results for that session are here and it looks like we were 7th quickest for the day, out of a total of 38 TT drivers for the weekend (we had several new TT drivers added after Saturday check-rides). I'm very happy with that lap time, and never thought we'd only be two seconds off of our old TT3 lap record in this old heap, but the track was fast that weekend and 6 new TT lap records were set - many of them on the Hoosier R7.

                            New MSR-H CW lap records set this weekend:
                            TTE - Team Black Armor - 1:49.525
                            TTC - Team Vorshlag - 1:43.733
                            TTB - Allan Page - 1:40.805
                            TT2 - Bill Woods - 1:38.550
                            TT1 - Raymund Guerrero - 1:37.114
                            TTU - Paul Costas - 1:34.301

                            Only the TTD, TT3 (our's) and TTF records remain unchanged from 2013.

                            So that was our first race report - probably too detailed and boring for everyone, but I wanted to explain the extra entries/drivers in our car, the challenges we had with the brakes and rear main seal, as well as show some of the competition we're up against. It should be a fun year!

                            Thanks Go To...

                            Big thanks to the Vorshlag crew for busting ass and getting the prep done in such a short time frame. Also thanks Matteucci for helping me at the track Saturday and letting me crash at his place both Friday and Saturday nights. He never got to drive the car due to the smoke and I feel bad that he didn't get any seat time. Sucks more because as he has a WRL race at MSR-H soon coming up.

                            I also need to thank him for the top notch car prep he did on the car for the years before we bought it. Matteucci owned, built and tested this car for three years and did all of the non-safety prep that wasn't detailed in my previous posts here. So much "old part replacement" maintenance, gutting the interior, got the car light, the crazy 3-disc clutch, the oil pan, the new Opti and more. We were damned lucky to get a car this well sorted to start with, as the work he did would have taken months to knock out.

                            Event picture and video gallery:

                            Five years ago Jason and I had seen the potential of this car and wondered why nobody had built one for TTC. When Matteucci wanted to build a TT car two years later I told him about the LT1 C4 in TTC and he jumped on it, found this car for a steal, and did all of this work to get it ready. After doing one RMS he found that it was leaking once again and just didn't want to mess with it - and neither did I, but I wish we had! I foolishly assumed it was something else, but was wrong. Would have been a much more enjoyable weekend without the smoke screen.

                            What's Next + Remaining 2015 Race Schedule?

                            These are the remaining Time Trial competition events we want to enter with this car in 2015:
                            • February 14-15 - SCCA Club Trials @ TWS
                            • March 14-15 - NASA @ MSR-Cresson
                            • April 25-26 - NASA @ TWS
                            • June 13-14 - NASA @ Hallett Summer Shootout
                            • July 31-Aug 2 - NASA @ Laguna Seca - Western States Championships
                            • September 4-6 - NASA @ VIR - Eastern States Championships
                            • September 26-27 - NASA @ MSR-Houston Counter-Clockwise
                            • October 17-18 - NASA @ "TBA" (???)
                            • November - NASA @ "TBA" (???)

                            You may notice that I have removed the USCA and Goodguys events from our season schedule. After some rules changes I strongly disagree with (that were actually aimed at our car), and what I felt was a botched Optima event in Vegas, we won't be trying to sneak Project DangerZone into these "street car" events - even though there are much more gutted, purpose built race cars racing in both. I'm going to give USCA another year to get the bugs worked out in their series before we jump into that circus again. We had only planned to do Goodguys in this car to test for USCA, and without a set of different wheels and 200 treadwear tires, the C4 isn't legal for either series at the moment.

                            Even though people think all we do here at Vorshlag is "work on Terry's cars" that is not at all the case. We had to squeeze in this prep in between customer jobs or after hours and only had time to do the basic safety prep, the brakes and tires, but just ran out of time to investigate the RMS, upgrade brake lines and fabricate the brake cooling this car obviously needs.

                            A dedicated track test like this is a MUCH better way to try out a new car BEFORE it is ever run in competition

                            And while this MSR-H NASA weekend was a great "Test" for us, and it was successful, the RIGHT way to do this would have been to get the car ready WEEKS before any competition event and test the car at a track somewhere, to work out the bugs and see where failures happen. Please don't take this one LUCKY example of us getting a car prepped in 8 days and winning/setting track records as the norm. It is not. Normally this quick-build process sans testing is a guaranteed way to look like a jackass and FAIL. But I'd rather be lucky than good...

                            The next event on our schedule is the SCCA Club Trials event, which we will likely miss. While I'd love to enter the Feb 17-17th event at TWS, which would be a great way to help that club grow it's PDX/Trials program and to test for NASA at TWS later this year, we're just too booked. We have some V8 swap projects we HAVE to wrap up for customers, plus the CNC machines are finally cutting metal, so Jason and I will be buried building hundreds of bits we need to fulfill backorders. There's no way we can work on #DANGERZONE in the next month so I have it stashed in my trailer for the time being. I will make NASA @ MSR-Cresson, however, and we will HAVE to do the RMS repair before that event.

                            We had talked about swapping the metal-puck triple disc pack for a Kevlar twin disc pack while the trans was out (for the RMS repair) but I kinda like the metal clutch now and I think we'll keep it. Front brake cooling and a new set of BrakeQuip flex lines will be built, for sure. We have found some clever ways to cool the brakes on a customer's C4 and we will employ similar tricks on this TTC build.

                            I'd like to address the body roll and brake dive this car has (see above), due to the stock swaybars and springs. The OEM replacement Bilstein shocks were also very "floaty" over the launch and anytime we touched a curb. The car handled like stock because it still had all the stock bits, but with 24 years of deterioration in many areas. The OEM rubber suspension bushings are disintegrated but we can replace those with non-metal bushings for zero points and $0 (Matteucci included a full set of poly bushings with the car). We still have 3 points left for mods - what do YOU think we should do with them? Here's a list of possible mods we might use the remaining points in TTC for:
                            • Springs +2. This could be aftermarket or OEM springs outside of the BTM 1992-96 Corvette options
                            • Swaybars +2. Burning two points would allow us to go with any aftermarket swaybar at both ends, providing its not cockpit adjustable
                            • Shocks +3. This is an expensive way to burn three points considering we have stock bars and spring rates
                            • Cold Air / Hood Venting +1. This is an unusual mod rule which allows all sorts of holes in the front bumper cover and hood for both cold air intake inlet as well as engine bay venting.
                            • Headers +2 points. As much as I'd love to do this its almost impossible to add real headers without taking +1 for moving/removing/replacing the cars and +2 for after-cat exhaust changes. And we're already at the limit for power at this weight.
                            • Adding 10mm of tire is +1 and adding 20mm is +3. That's tempting but I felt like we had more than adequate grip and tire wear was very good.

                            Give us your input - we'd love to hear what you think would make DangerZone faster. Remember: we have a very tight budget for purchasing parts and only 3 points left to play with in TTC. While I'd love to go nuts with an expanded TTB build of this car (and another 20 points of mods), that isn't in the cards this year.

                            Low Profile Build? Not So Much

                            This build thread has exceeded my hopes as far as how many people have read it (many thousands). We're posting it on 5 forums now (GRM, NASA Texas, SCCAForums, Corner-Carvers and Vorshlag) and I had probably 50 people talk to me at the NASA event and say they enjoyed reading it. One piece of potential bad news is that we now have some extra scrutiny at the highest level. We heard that the National PT/TT director Greg G has noticed our little build, as well as one other recently built Corvette TTC entry - Dave Schotz. Greg even called our TT director at the track and asked about our car. Uh-oh...

                            We know Dave from both his owning SCCAforums (one of the places we are posting this build thread) as well as his many previous wins in SCCA and NASA. We found out that he quietly built a 1991 Corvette and ran it in TTC for the first time a week before we ran our car. He told me he has always wondered why nobody built a C4 for this class, and when the tire points changed this year he decided to build one to replace his TTC Camaro (shown above in 2013, when he won THREE national titles in the same week!). With minor race prep and a set of 275mm R6 tires he has already racked up wins and a TTC track record at his first event. I won't say any more than that as Dave is likely to run his car at NASA Nationals West and he doesn't have "public build threads" like we do. If we can, we'll run our car at NASA Nationals East and hopefully NEVER have to run head-to-head with Dave... because he has a LOT of national championships.

                            Unfortunately this car Dave built, and our car if it does well, will probably get the C4 Corvettes a lot of scrutiny at Nationals and if either one does well, it might get these cars re-classed next year. I hope that isn't the case, and I expect that Greg will look at Dave's previous wins in a number of cars as well as the work we're doing before he makes any big changes. This car has been classed in TTC (and even TTD) for 5+ years without any alarm bells going off. Just a fluke that two serious C4 Corvette TTC builds happened to debut one week apart... what can you do? I'm just hoping we can make it through this season without any road blocks or rules changes... I like the car and want to continue developing and racing it for this season.

                            Until next time,
                            Last edited by Fair!; 08-05-2015, 06:08 PM.
                            Terry Fair -
                            2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
                            EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


                            • #15
                              Re: Vorshlag Budget TT Build: Project DANGER ZONE

                              Project Update for April 9, 2015: Wow, I started writing this about 3 weeks ago (March 18th) and never finished. I lost the last 3 weeks to our new CNC machines, which I have been manning non-stop 24/7, trying to build a lot of parts to fulfill backorders. Somewhere in the last month - and I'm having trouble remembering back that far - we ran NASA @ MSR-C, and the weekend before that (COTA). We also prepped and took 11 cars to the Optima event March 28-29 at TMS, where I raced a C5 Corvette. Anyway, we took the TTC C4 and our TT3 Mustang to the NASA event, but I will break up the "race report" into another post. Let's look at the prep work that we managed to sneak into the C4 before this latest NASA race. It was a lot of work, but maybe not quite enough...

                              Roll Cage + Nets + Dash Rework Completed

                              About 3 weeks before the MSR-Cresson event I pushed the C4 onto Ryan's plate and he took over the front half of the roll cage fabrication plus the remaining safety gear that needed to go into the car before the next event. It took him less than 30 hours to do all of the work below. I wish this could have started sooner but our schedule is always packed and we can only squeeze in work on our shop cars when we get a small gap.

                              The "back half" of the cage was built as a bolt-in roll bar, since we ran out of time to fully cage the car before the January event.

                              We noted that my helmet was in a tough spot when making the 4-point roll bar in January, and as you can see above, any roof cage structure that was kept inside the window frame would be INSIDE my helmet. As it was the targa structure was touching my helmet - this car is narrow inside, up top. I didn't think me leaning at a list to starboard was the safe way to drive, so we pushed those upper cage tubes outside the window track.

                              Will this affect airflow? Maybe. Will this positively effect drag reduction and top end speed? I highly doubt it, and nothing short of wind tunnel testing could prove it either way. Is it safer this way, keeping a piece of 1.75" steel tubing away from my helmet? OF COURSE IT IS. So we did it - its the safest, most common sense routing for this car and this driver. It looks a little odd, but its the right solution - this side of getting a shorter driver. My seat is already touching the floor - which we cannot alter.

                              The front, upper cage tube near the windshield surround also follows that contour closely, again - to keep it away from my head. It sits as high up as possible, to prevent the cage from restricting my forward field of view. The unusual angle of the upper tubing junction there was later gusseted with more tubing, shown lower in this thread.

                              An "FIA" style vertical crush prevention bar is also added, which narrows the side door opening but makes the heavily raked windshield and A-pillar structure much more "pancake" resistant in a crash that put the car on the roof. I would like to keep my head and spine as delivered, thank you very much.

                              Note the tight joint fit-up in the above right pic. After this point in the cage build (we missed taking pics of the door bars) pretty much everything was built and tacked in place, then the cage structure was completely pulled out of the car, in sections, to do the final welding.

                              Sub-assemblies like the NASCAR-style door bars and load plates (above) were welded on the fab table, for easier access to get to the bottom of tubes. The FIA bar was welded to the A-pillar bar, things like that. Standing on your head to weld upside down inside a car is the suck.

                              After the roll bar and cage sections were removed the B-pillar roof hoop was cut out of the car, lickity split. Yes, this was deemed necessary to gain access to the upper tubing joints for welding. The cage structure far exceeded the OEM rollover protection of this piece, and it was welded back in later. Luckily there was a body seam there that covers up the outer fiberglass cut. It won't have to be body worked.

                              The picture above skips ahead a bit, where the cage is almost fully welded and back in the car, and the roof structure hoop was welded back in place. At this point it is getting close to being done. The upper front corner gusset tubes are shown here, and yes, they do land on the FIA bar. It was another compromise to keep from having to cut a giant chunk of the already weak windshield frame away at the A-pillar. The roof diagonal is also shown in this top-down shot.

                              The tubing above ties the front downbars into the firewall at one of the few places that has any metal. This is still a mostly fiberglass car, and the front half of the floor pans, trans tunnel, and most of the firewall is all just thin fiberglass. Can't exactly weld or land metal tubing onto that structure. So Ryan picked the farthest outer edge of firewall, which is metal at the base of the A-pillar, and tied some short pieces of 1.5" tubing from there to the main cage. This is to prevent TIRE INTRUSION into the cabin in a heavy crash, and for a car like this, well worth it. It doesn't pass through the firewall or tie into any major structure there. The upper OEM A-pillars are still free floating, since there is no roof structure (its almost identical to a convertible in this respect). With the OEM targa roof removed and the windshield out, the windshield surround is surprisingly weak and flexible. Oh well... we cannot tie into the A-pillar in any substantial way without taking more performance points for TTC/PTC.

                              The door bars are pushed outwards to almost the skin of the fiberglass doors, and the factory impact beams were removed. This is to give a lot of ROOM to the driver's arms, and the extra room is appreciated. These bars have a lot of curves in them, to fit this crazy chassis, so they were tied into the outer frame rails in 2 additional spots, as shown above. This makes them stronger in a side impact, and the bars and frame would both have to deflect a lot to touch my arms. I'm rather fond of my arm and would like to keep it attached to my body.

                              Another thing the upper side cage bars do is go UPWARDS from the B-pillar joints/factory roof structure hoop, to give me more head room in a rollover. The seat is bolted right down to the floor, without a slider or any risers, to increase headroom. The only other trick left is to lower the floor - which costs performance points in TTC, which we don't have to spare. Everything in racing is a compromise.

                              Non-Cage Stuff + Safety Upgrades

                              Our friends from Titan Auto Glass (above) came out to re-install the windshield after the welding was complete. They had already been out a few weeks earlier to remove the new windshield they had installed in January - an added expense of doing the cage in two different time periods, with a race in between. Always, always get the windshield out of the way for a cage job.

                              The 14" wide panoramic mirror from Longacre was mounted to fit my driving position. With the driver's side mirror I have an unobstructed rear view. The passenger side door mirror is broken and useless, for now.

                              continued below
                              Last edited by Fair!; 04-23-2015, 08:44 AM.
                              Terry Fair -
                              2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
                              EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev