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Vorshlag C4 Corvette TT Build: Project DANGER ZONE

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  • #31
    Re: Vorshlag Budget TT Build: Project DANGER ZONE

    Continued from above

    Five seconds slower, just from lack of control. It wasn't "more rolling resistance" or "not enough heat in the tires", no the cause was "bouncing off the bump stops" with an uncontrolled suspension setup. The GRIP was definitely there, but I simply couldn't use it when the track got bumpy.

    I parked the C4 and ran the two remaining TT sessions in the BMW, where we had a shot at winning TTD class. And we did win on Saturday, but it was close. The C4 was WAY back in the TT2 standings from this lone session with 2 hot laps.

    Good party Saturday night, but it was cold all day and into that night. It was 32°F in the morning, got up to the low 40°F temps during the afternoon, but the wind never let up and we were always cold Saturday. The track did warm up enough to put some quicker TT times down at the end of the day.

    It was foggy, humid and damp for the first TT session but I wanted to get another lap in the C4 out of the way, so I ran that car first. I finally put the vidcam in, dried off the dew inside the windshield and back glass (we really need a defroster in this car), and lined up in 18th out of 38 on the grid for TT Session 1.

    Click here for in-car video of the bumpiest, scariest lap around MSR-H

    After getting out of traffic on the first lap I made one hot lap and ran a 1:46.991, quicker than I drove Saturday, but still 3 seconds off my 2015 TTC lap record on the little tires. The lap was still very sketchy, bouncing around like crazy. You can hear me comment on the video with things like "Wow, that was scary" after Turn 13. The rear suspension was hitting down on the bump stops and going up to full droop... it was much worse inside the car than the video shows.

    With the same minimal safety requirements as HPDE, there are stark differences in safety gear used in TT cars

    As I came around the last turn on the lap shown above there was a C5 parked in the middle of the track, right under the Start/Finish stand. It had just backed into the pit wall hard and was totaled. The driver is lucky to be uninjured - he was using nothing more than a helmet, stock seats and stock 3-point belts. I had to back off and pull off line to miss the car (it happened only seconds before I got there, and there was not a yellow at the previous corner station yet). Made me appreciate our decision to fully cage the C4 and invest in a HANS and other safety gear. And made me rethink letting Amy out in her TTD BMW with none of these things, too.

    I am posting pics of the crashed TT car to share what can happen to people at any track event, if things go very wrong. I hope that maybe some folks will have that "light bulb" moment after seeing this and upgrade their personal safety gear. /off soap box

    Once again, after the first TT session in the Corvette that day, I came in and parked it. Nothing had improved magically overnight and it was still way under damped for these tires, springs and track surface. Everything was moving around, uncontrolled, and I recommend you NEVER do this. The sad thing is that I knew better, damn it. I might should have gone with smaller 315s and of course spent the money on REAL shocks before trying this test. I just got greedy!

    With fielding 2 track cars this year, a business to run, and coming out of our slowest time of the year I just couldn't afford the $4500+ in dampers and springs and bushings that these tires demanded. It was a gamble but it didn't pay off. Running these big, sticky tires on 25 year old shocks was flat out dangerous. #DangerZone was supposed to be a joke, not a real motto!

    Parking the C4 for the day freed me up to be able to ride right seat with Amy (above left) in an HPDE3/4 session, to try to instruct a bit and get her confidence up. In just a few laps she had found 2.5 seconds (it was all in the braking zones) and was back in the TT fight. It felt good seeing that big of a time change just by giving her a few pointers. I might actually try to Instruct with NASA again... I kind of miss it.

    I ran the BMW in 2 more TT sessions (2 and 3) mired in traffic, but I had what I thought was a healthy lead in TTD towards the end of Sunday so I let Amy drive the E46 in the 4th TT session... and sure enough, her BRZ competitor in TTD found a bunch of time and got the win on day 2. Oh well, we still have a LOT of work to do on this Bimmer.

    Left: On Saturday the C4 was 6th in TT2, 330 was 1st in TTD. Right: On Sunday the C4 was again 6th in TT2, 330 was 2nd in TTD

    This race weekend was a mixed success. The up-classed TT2 Corvette was way off the pace for both the class and the times I had driven here last year in TTC. That car took 6th out of 10 in TT2 on day 1 and the had same finish position on day 2. While the suspension setup was a bust, at least it ran reliably, was leak free, and the rebuilt engine never skipped a beat or blew any smoke. The BMW 330 was also a bit off the pace of the old TTD track record (1:48.4), but it did OK for such limited prep in its debut event, with one 1st and one 2nd place finish for the weekend.

    Hey.... we don't need TWO Archer themed Corvettes, hah

    We learned plenty at this event and still had a LOT of fun - seeing friends, the Saturday night NASA party, and both of us getting plenty of seat time in the BMW. The dismal results in the C4 made me rethink this new direction for Project #DangerZone.


    After the shellacking I took at MSR-Houston, we had nearly 2 months to think about the C4 would need to do to make it a more competitive (and safe) TT2 entry. I started adding up the cost of parts and the work it would need:
    • $4500-5500 in MCS doubles, springs, and Vorshlag spherical top mounts
    • New Delrin/Poly/spherical bushings at every suspension pivot location
    • A new set of heads, camshaft and valvetrain upgrade, maybe a new intake manifold (to his 380 whp)
    • Full length headers, custom exhaust, and a better tune (to his 380 whp)
    • Custom flares at all 4 corners
    • Splitter, big wing, ducted hood for some downforce
    • Thermostatically controlled oil cooler, Accusump, and other oiling system upgrades
    • Aftermarket carbon fiber hood ($3000) to lose more weight

    The list kept going beyond this, which was long after my budget gave up. These numbers just didn't make sense a car we really don't make any parts for, that is based on 33 year old chassis, and with a motor I had just spent several thousand dollars to have rebuilt to painfully stock specs. What was the purpose of this TT2 class move? Just to have "faster lap times", but yet give class competitiveness or require a LOT more money to handle as well on the big tires? Deep thoughts.

    We kicked around some ideas internally and on Corner-Carvers about an LS swap, but the hours and cost projections kept spiraling out of control. This C4 was supposed to just be our "tweener" build, done on a tight budget, to bridge the gap between our TT3 Mustang and the Next Big Shop Build. Now we were talking about a $40K+ showcase car... that was based on a vintage chassis? This didn't really reflect what we do at our shop, and was the epitome of bad judgement, so I went through the Pros and Cons for a week or two.

    Meanwhile I asked our crew to look into a couple of small fluid leaks that I only noticed in the trailer coming back from the MSR-H event. First fix was building a power steering catch can, shown above. The pump was spewing a small amount around the cap.

    We had this non-vented oil catch can lying around from another project, so that was re-purposed to catch the puke from the power steering pump that was getting past the (new) fluid reservoir cap. The next was an oil pan drain plug leak that has been weeping just a little fluid. I abhor fluid leaks, and the new copper gasket fixed that, mostly.

    As I was staring at these big, meaty tires one day, Ryan pointed out that the rear tires had slipped on the wheels. He had marked the location of the tire valves when he installed these 345mm A6s and they had slipped a good bit (the fronts had not). Must have been from that massive 354 ft-lbs of torque, LOL! Not uncommon on freshly powder coated wheels, so we will scuff up the inner lips once these tires are off, which should give enough bite to keep the tires from slipping.

    By this point I was thinking of ways to get the car back into TTC, but how do we cover up that MESS that I made of the fenders?? We cut all 4 fender lips off to clear the big tires, and the car would look turrible with the 245s back on.

    Around that time an old college buddy, Jason, brought his BSP autocross prepped 1989 Corvette by the shop, above. He took off the 17x12" autox wheels and mounted up some 18x10.5" Z06 street wheels at all 4 corners and got the dang thing registered and inspected. It being over 25 years old made for a simple $7 inspection of lights, wipers and horn. And the Vintage plates were like $70 for 5 years! But more importantly, I looked closely at his rear flares. These were just the GM "export" flares for the C4, also used on the 1996 Grand Sport to cover a slight poke from a 17x11/315mm factory rear tire they used. Hmm.

    Jason and I had discussed the C4 many times over lunch in the following weeks, and I was bouncing ideas off of him about the "Big Tire" test, how badly it went and how expensive it would be to keep going down this path. He, like many others, told me what I didn't want to hear... you gotta give up the big tire and put the car back in the class it was built for: TTC. I had also acquired another chassis to build for a shop car that could actually bring us some actual business, so investing a lot more in the C4 was not wise.

    345 vs 245 Hoosiers - just look at how much rubber I'm having to give up!

    One argument made was that a fully prepped TTC Corvette would sell for more than a half-assed prepped TT2 C4. This was a difficult choice, but it made the most sense for the business. Painting the car and cage would help resale value, and that was something I needed to plan for.

    Yeah, it was time to go back to TTC for Project #DangerZone.

    I decided to buy a pair of the Grand Sport flares, just to see if they covered up the sins we created when we cut the rear fenders to clear the 345mm tires. Sure enough, the rear fender cuts are almost 100% hidden under these... so we conceivably have an easy way "back to TTC", if needed.

    With the sticker set of 245s already mounted on the 2nd set of SSR 17x9.5" wheels it was a quick change to go from 335F/345R A6 tires to the 245 R7s. I re-ran the numbers, weights and power for the 2016 rules and realized that since the car had to weigh 3260 pounds for this year, now we could make up to 291 whp. And since the rebuilt 1992 LT1 made 288 whp (SAE corrected), I wouldn't have to run even more ballast to make up for the 4 extra whp it makes now (it made 284 whp before the rebuild). So for 2016 we would need to just run the 58 pounds of extra "minimum weight" ballast.

    One small last thing I decided to modify for TTC use now was to locate a second pair of the Bear Racing .875" thick spacers for the front, keep the rear spacers in place, and widen the track with the skinny tires. We can increase track width up to 4" over stock in TT-Letter classes without a penalty, and this spacer addition would add 1.75" of track at both ends. More mechanical grip is the payoff, and if you can keep the tires out of the side air stream it doesn't add any aero drag.

    This is what we ended up with, above. It has some monster fender gaps but the car is actually sitting very low (maybe too low - we are addressing this soon). At this point I had pulled the "TT2" class designation decals off and Jon was cutting some "C" decals for all 4 corners. I signed up both cars for NASA @ MSR-Cresson - TTD in the BMW and TTC in the C4 - including one Instructor entry for me. Amy was supposed to run the BMW, but had a death in her extended family which required her to travel across country over the race weekend, so at the last minute I was looking for a way to get both cars to the event...

    NASA AT MSR-CRESSON (1.7 CCW) MARCH 12-13, 2016

    It rained the entire week before this event but it looked like it would clear up sometime Saturday. I mentioned to my crew here that I needed someone to fill in for Amy. Our Order Desk Manager Jon started talking a bit of smack, so I surprised him with an offer to drive the red BMW in HPDE, and he took it. We did some last minute prep on that car and he drove it out to Motorsport Ranch Cresson on Saturday morning. I left the shop at 7:20 pm on Friday night with the C4 in the trailer and slogged through the rain to get to the track. I was unhooking at 9 pm, in the pitch dark, parked in the grass, on a steep hill. There was NOWHERE to park, as even with the rain looming, over 200 people showed up to run HPDE, TT, and W2W.

    continued below
    Last edited by Fair!; 03-25-2016, 08:55 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


    • #32
      Re: Vorshlag Budget TT Build: Project DANGER ZONE

      continued from above

      Saturday morning it was still wet and sprinkling, so I drove the BMW in the TT Warm Up on street tires, with Jon riding shotgun. I had hoped to show him "the line" (this was his first time driving at MSR-C), but anywhere on the 16+ year old, original track surface that was "the line" was polished smooth. Add in the water and it was like driving on ice, so the trick in the rain here is to NOT drive anywhere near the proper driving line. The marbles is where the grip is, strangely enough.

      Event Photo Gallery:

      After that drift-fest TT warm-up we came in - and realized we forgot to install the AMB transponder on this car. No official time, doh! So that meant that I would be gridding in the next TT session at the back, no matter which car I brought to grid. I ran the red 330 again and got a time good enough for the win for the day, but I was itching to get into the once again TTC classed C4. This would be the first time it has been run in TTC with the fresh motor, on a sticker set of tires, with the upgraded spring rates, and the "rebuilt" OEM shocks. Aka: the most prepped it has ever been for any class.

      After lunch the rain finally let up and began to dry, so we unloaded the Corvette. The track surface dried off in TT session 3 and I took the C4 out for the first time on Saturday. We had 6 cars in TTC class so whoever won today could potentially take home 2 Hoosier tires. I was mired in traffic and couldn't get a clear lap, ran a 1:24.X in the session with 2-3 passes per lap, but I at least moved up the grid. The old MSR-C 1.7 CCW track record for TTC was a 1:25.1, and both BJ and I had both beaten that already.

      In the final TT session of the day I was trailing BJ Meyer badly in his TTC prepped Mini Cooper S (parked to the left of me in the image above). Supercharged, on coilovers, lots of boost, and driven well at this, his home track. In the final TT session of Saturday I put down a blistering 1:22.206, with only one semi-clear lap for traffic, with a number of small driving mistakes. But BJ put in his personal best of a 1:21.996, taking the win for the day. My time was good enough for 2nd, but I knew I had more in the car - predictive showed some high 1:21's but traffic kept killing my best laps. At least I'd be further up the grid for Day 2!

      Jon was in HPDE3/4 and as the track dried up we swapped on the Hoosiers and he was having a blast. I saw the TT "needle go into the vein" for Jon this weekend... he's been cooking up TT builds on paper all week!

      Sunday morning was a bit of a mess, and it was my fault. This was the Daylight Savings "leap forward" day, where we lose an hour at 3 am. My smart phone alarm can catch that, of course, but the problem was I set the alarm for... a weekday. So I overslept and made us super late to the track. We rushed to the track from the hotel but I made it in time to get into the 330, throw some fuel in it, and make it to grid with 1 minute to spare. I ran the first TT session in the BMW and again was mired in traffic. Getting a good lap in a gutless car that cannot pass anything is actually pretty difficult. I ran a 1:27.604 in the car Saturday but only managed a 1:27.854 on Sunday in this, the only session I ran the 330. Turned that car over to Jon for the rest of the day and spent the the other trying sessions to chase down that damned Mini in TTC!

      In TT session 2 the Corvette was at least gridded 11th out of 39, so there should be a better chance of getting a traffic free lap? Well, not so much. I was on a quick lap and lost track of which car I was in... there's three left handers (T5 - T6 - T7) in the back section of the 1.7 course that I can take with the throttle matted in the TTD BMW, but not in the C4. Well I mis-remembered that, and kept the gas pedal mashed, and put two wheels off at the exit of T7 (Tombstone). And the grass was still wet, so that two off quickly became 4, which turned into a big graceful loop across track and into the grass. Yea, I spun it, which DSQ'd the session. I came back in and tried to get my head on straight.

      BJ was checking to see if I was going out in TT session 3, and I told him that I damn sure was. So I got to grid for that session and all 3 of the top TTC cars were lined up pretty closely. BJ's Mini was sitting on a 1:21.8, I was gridded right behind him, with Mark Schnoeer's TTC M3 just behind us both with a 1:24.8 (last year's record setter). I needed to get the lead out and put a clean lap in for the day in the C4. I knew the C4 had enough performance in it to beat the Mini - it had beaten it every time before - but there was the whole driver thing I had to do.

      I didn't know how much more the master cylinder had in it, but I was going to push for the win in this session. The first two laps of this session were traffic, and I passed some of the faster cars gridded ahead of me, but BJ was always right there about 30 yards ahead, too. By the start of the fourth hot lap I had passed the cars ahead I needed to, built a gap to BJ's Mini so I wouldn't be running into his mirrors, and got the 245 R7s up to temp. The brakes felt OK so I went for and achieved my best lap of the weekend....

      Sunday TT Session 3 in-car video

      All weekend I'd been touching 106 mph entering Big Bend and on the next straight reaching 110 before braking into T9. With these short tires, 110 mph is at the top of the rev range for this LT1 engine, so I started using 5th gear right before the start finish, and it gained me 2-3 mph (noted 112-113 mph into T9 on those laps). If you listen carefully in lap 3 in the video above, as I'm exiting the fastest corner of the course (Big Bend) I am running out of revs in 4th gear, so once again I planned to use 5th. I looked and saw that Predictive Timing showed me 1:21.6 right as I go to grab 5th... and CRASH! Synchros balk not once, but TWICE! It finally went into gear as I'm cursing the Germans who built this gear box. Even missing 5th gear twice the AiM logged a 1:21.90 lap time.

      Son of a... Hindsight being what it is, I should have left it in 4th, because the 5th gear synchro has been "hit or miss" since we bought this car. Its an EXPENSIVE rebuild on this ZF 6-speed, too. Would it have been enough to get ahead of BJ's 1:21.618 he ran in that session? Who knows. At least I knew I had dipped into the 1:21s, which was a goal all weekend.

      To make matters worse, after lap 4 in that stint I lost the brakes almost completely, with a VERY long pedal braking into T9. No brakes and no way to fix it at the track, so I missed the 4th session. Oh well, that 1:21.9 would still feel good for 2nd.

      No, it just keeps getting better! The AMB timing loop borked that lap and showed it as a 1:03.786... Of course they had to throw out that bogus time (which was during my best lap of the weekend) and used my next quickest of 1:22.786 from that session (in traffic). Sure, its nearly a second slower than what I really ran, but I get it - timing equipment isn't infallible.

      Even with a solid margin for Sunday, and after I told him I was done for the day, BJ still went out again in TT session 4 and dropped to a 1:21.589, resetting the TTC record with a strong number. So once again I was 2nd place in the C4 for the day.

      During the weekend I was instructing with 4 different HPDE1 students, and sometimes sprinting to the grid to meet them in time for their sessions after getting out of the two TT cars. The grid was way back on the 1.3 mile course, due to the lack of paved parking area on this wet event site. Instructing was fun but made for a hectic weekend and a lot of running around - I need to get a scooter or small track support vehicle, something to get around the paddock in.

      So once again the weekend was a mixed success. Driving two TT cars + instructing + talking to customers at our ever-busy trailer makes for a hectic weekend, but it was also a lot of fun. Jon got a check ride for TT and should have his comp license the next time he shows up to a NASA event. I managed two 1st place finishes in TTD (with only one timed TT session each day in this very under-prepped car) and two 2nd places in TTC. At least we were closer to the class winner in the C4 in this class, and we smashed the old TTC track record by nearly 3 seconds (but BJ reset it 3.5 seconds quicker than last year).

      We run the same 245/40/17 Hoosier R7 on both cars, so the C4's old tires become the BMW's new rubber, heh. After switching the tires on the BMW back to the streets we moved the trailer to pavement and loaded the Corvette for the trip home. If there was any brake pedal I'd have run the last session to try to chase BJ Meyer down. After instructing in the 5:20 pm HPDE session, I didn't get out of there until after 6 pm, and that 2 hour tow home made for a another 12 hour day. But compared to my normal 7 day a week work days, this was a breeze!


      After seeing results that were quicker on the 245 R7s vs the 345 A6 tires, it looks like we're heading back to TTC for the rest of this season. Jumping 3 classes up with just a tire change was foolish, and the proper path involves spending a lot more money than we have budgeted for this car.

      At a smooth track like Cresson I ran a 1:23.7 in January at the SCCA Club Trials on the Big Tires (335F/345R), yet I ran nearly 2 seconds quicker (1:21.90) on the little tires with no other changes in March. Being the "fastest car of the day" in January gave me a false sense of confidence, and over-shadowed how the car felt in bumpy sections of this course. At MSR-H the car was tougher to drive on the Big Tire setup, just due to the rougher track surface. In TT2 there I was 3 seconds slower than my 2015 pace on the narrower TTC tires.

      Please don't confuse this handful of "data points" with busted theories that "narrower tires work better" on a road course for any given car. I made some posts on Facebook (#SmallTiresMatter) that were in jest, but several people took them seriously. We've proven the small tire theories wrong, time and time and time again. A lot of folks have a lot of theories on why we were quicker on the narrower tires, but trust me... its just a simple matter of the current shocks not working well with the MUCH higher grip levels the wider tires made.

      With the right shock and spring package it would be quicker on the Big Tires. Always. We made big drops in lap times on our TT3 Mustang on each jump up in tire size, going to the same tracks. We went from 265 to 305 tires, 305 to 315, and 315 to 335/345, and each increase in width was a drop of 2-3 seconds per lap. Big Tires Do More Work. You just have to upgrade the rest of the suspension to deal with the higher mechanical grip levels. 25 year old OEM dampers ain't the hot ticket on 345 HoHos!

      If we had the points for TTC, I'd still install some adjustable MCS dampers for this car. There are still handling issues on even the smaller tire with the factory shocks, just not as pronounced. We're just "point maxed" for TTC right now and cannot add any more mods. Raising the ride height will reduce the chances of hitting the bump stops on bumpy courses, which it still does on the 245s, so that is planned before the TWS event. Here's our TTC build point budget:

      Base classing: TTC*, 3260 pounds
      - 7 penalty points for the base class "star"
      - 10 points for the Hoosier R7 compound
      + 1 bonus point for running 10mm smaller than TTC base tire of 255mm
      - 1 point for cold air mods / vented hood
      - 3 points for spring rate change
      = 19 points allowed within the first class (1 more point moves it to TTB)

      Shocks would be 3 more points we don't have. The inherent TTC class competitiveness on the smaller tire, and budget constraints, just doesn't make sense for us to upgrade the suspension and other parts to make the big tires work on THIS car.

      For TTC use this season we do have some small changes planned to make the car easier to drive and maybe a tick more competitive. A change to a smaller diameter racing steering wheel and a quick release will make it easier to see gauges + easier to get into the cabin of this car (after removing the steering wheel and hanging it out of the way).

      A full Tilton brake and clutch pedal assembly and firewall mounted Master Cylinders will be going in soon. Those will replace the factory pedals and OEM master cylinder (for zero class points), so we can hopefully get past these crappy reman MC units failing so often. Removal of the OEM plastic brake booster is another failure point we can lose, also.

      Next few NASA Texas events:
      • April 22-24 – Texas World Speedway
      • May 21-22 NOLA Motorsports Park – Crossover with NOLA
      • June 11-12 – Hallett Motor Racing Circuit

      After that we will add the small over-flares to fix the cut off fender lips, then maybe... hopefully this summer, get some new paint on the body and cage/interior. Check back next time to see what we do next to #Dangerzone to hopefully make it less dangerous!

      Last edited by Fair!; 03-25-2016, 05:16 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


      • #33
        Re: Vorshlag Budget TT Build: Project DANGER ZONE

        Project Update for November 9th, 2016: On this, the day after an historic election, I think we need a distraction. Let's talk about race cars - welcome to the #DangerZone!

        A lot has happened to our C4 Corvette since my last post. We developed a custom dual Tilton master cylinder brake setup to replace the constantly failing stock masters and booster. Then we tested that at an HPDE event and it worked flawlessly. Then we prepped the car for paint and off it went to my buddy Shiloh's shop. Afterwards the car came back SO beautiful we felt obligated to spruce up a few other things. Long story short - its now too pretty for me to own and race anymore, so the car is For Sale. Read below to catch up!


        After four rebuilt OEM brake master cylinders failed on this car we were out of patience with the stock parts. These were not lasting a weekend and the failure mode was pretty abrupt: one lap you solid had brakes, then on some random corner the pedal would go to the floor and you had nothing. Bleeding wouldn't help a bit. Luckily none of these failures led to a crash - so far.

        Jason had been wanting to make a brake solution to fix a situation just like this for years. This would replace the stock bake master cylinder and brake booster. As I have mentioned in the past the stock booster is PLASTIC on the C4 and they fail regularly as well (this car already had one rebuilt unit installed).

        Real race cars tend to not use vacuum assist brakes or OEM stepped bore master cylinders. For safety and tune-ability they use two separate master cylinders, which can vary in bore size, and tend to use them with new pedal(s), either hung from above or from below.

        Racing dual aftermarket master cylinder setups are almost always setup with one master cylinder for the front and one for the rear, plumbed independently for safety. A "balance bar" can then be employed to adjust the brake balance from front to rear quickly - literally by pressing on one master cylinder more than the other, via a lever at the brake actuator rod.

        Race cars with manual transmissions (which is most) will often also replace the clutch pedal and master cylinder at the same time, so there are 2 pedal/3 master mounting kits you can buy. And if the brake and clutch master cylinders are hard to access (on the floor or under the dash) for fluid checks/refills, the fluid reservoirs are often remote mounted elsewhere, like above.

        The trick in mounting these into an OEM chassis is having something to mount them to - usually top hung pedals are mounted to a roll cage tube, and bottom hung are mounted off the floor. Those both take lots of time to mount and brace. Sometimes you can mount the brake masters and new pedals right to the firewall, but usually they still need some support from a roll cage. We have done dual masters all 3 ways.

        There are complete "pedal box" kits you can order, sometimes even for a specific car. Most race cars with gutted interiors and roll cages are built using generic pedal kits, like the Tilton above. Mounting top mounted or "hung" pedals from a roll cage tube is a good bit of work, and there is still a lot of factory wiring behind the dash panel on this car (it has all of the working gauges). Floor mounted pedal boxes are slightly more common.

        These are the parts we sourced - the Tilton MCs, Tilton balance bar, Tilton remote knob, and the pedal multiplier

        The main issue we had was that the factory floor on the C4 is too narrow and is somewhat weak (fiberglass) and the firewall isn't really open to adding in more mounting holes (fiberglass), but the OEM brake booster opening is fairly strong - see below at left.

        We also didn't want to replace the stock pedals because, well, that's a bunch of work that is very difficult to un-do. We wanted to test a theory so a bolt-on solution that uses factory mounting holes was preferred - if this didn't work we could just put another new brake master and booster back on.

        The solution (above) we came up with is a setup that has a CNC billet aluminum bracket / mount that bolts to the OEM booster mounting holes at the firewall. This way we could keep the OEM brake pedal arm and bracket. No cutting, no fabrication to the car at all, purely a bolt-on assembly. This firewall bracket has a pedal multiplier setup built inside that changes the pedal effort for the now manual brakes. This make the brakes have more of an OEM-like amount of brake pedal travel. We might never make another one for a C4, but this would be a good test for an idea for other, more relevant cars that might need this solution.

        Forward of this billet firewall bracket are four studs that hold a steel bracket, to which the two Tilton master cylinders are mounted. In between the pedal multiplier and the masters goes the actuator rod and balance bar. This leads to a dial on the dash to adjust front to rear bias on the fly.

        It took some tricky machining on our CNC mill to make the main billet aluminum part, but we wanted some new challenges for our machines. Jason made this piece in 3 CNC setups and mounted the pedal multiplier to the main pivot.

        Ryan built the steel bracket that the two Tilton master cylinders mount to from a CAD drawing. Then all of this was bolted together into this assembly shown below. He then made a custom actuator rod that connected to the factory brake pedal under the dash. The rest of the pedal assembly was left stock. This was done to make this a bolt-in upgrade.

        Once installed on the car we had to find a place to mount the 1995 Corvette ECM, which normally goes on a bracket near the brake booster. The solution is shown above, which unfortunately hides some of the sexy machined bits in this new, dual MC manual brake setup.

        We did not want to chuck out the ABS system so we plumbed the return lines from the ABS pump into a Y-fitting that fed back to both master cylinders. This allowed us to keep the ABS functional.

        The Tilton balance bar adjustment knob was mounted to an aluminum panel on the dash that also holds the Traction Control switch (it defaults to off now). We initially tested this new setup on the street, and quickly changed master cylinder bore diameters to get more braking force. Even using the best hydraulic ratio formulas you often have some trial and error - we were close, but needed one more iteration. The pedal effort is firmer than before (no vacuum assist) but the pedal travel is perfect and heel-toe is still easy. We then needed to test the car on track to prove it...


        During this brake master upgrade period we also made some other small changes to the Corvette, to make it more reliable on track as well as to clear up any TTC class legality questions.

        Earlier in the year, as we were fighting brake master cylinder issues that we couldn't diagnose easily, we threw some hastily made brake duct inlets and backing plates on the front of the car. That was when we briefly ran the car in TT2 class, which has no aero restrictions. The easy place to add the brake cooling air inlets was under the front nose. Because this is not exactly a good high pressure spot I decided on some vertical panels (see above) on the outside of these 3" round vents, to keep air from spilling away laterally from the inlets.

        After some discussion with two different NASA race directors it was felt this vertical plane we added was in "a grey area" that could be protested, and someone could argue this deflector as a "canard" or "air dam". No, these didn't provide any downforce, and actually probably added a little lift, but they look like canards and the NASA rule book doesn't define terms like "canard"... its all up to the rules maker or protest judge to interpret the rules however they see fit. So to remove any doubt, we redesigned these brake duct inlets and removed the potential brake cooling "canards".

        These plastic NACA ducts had an identical 3" hose connection and they were, in fact, much easier to install than the work needed to fabricate the "canards" and and brake duct inlets we had used before. Are they as effective? Hard to say without some very detailed testing, but these were deemed TTC legal without any doubt (or points) by the same race directors, so they went on.

        A fire proof Nomex shift boot and aluminum mounting base were then added. We use this Joe's Racing shift boot kit on many builds, dating all the way back to our Alpha E36 LS1 car back in 2006. This boot goes over the old rubber transmission tunnel boot that was now 25 years old. This Nomex boot added a layer of noise, exhaust, and fire sealing to the stock transmission tunnel.

        continued below
        Last edited by Fair!; 11-09-2016, 07:05 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


        • #34
          Re: Vorshlag Budget TT Build: Project DANGER ZONE

          continued from above

          I had noticed a bit of heat on my right leg in long stints so Brad added the thermal / reflective DEI material to the trans tunnel (see below), which is adhesive on one side. This has a layer of fiberglass insulation underneath the infrared reflective layer on top. We use this DEI insulating material on all sorts of cars to shield passenger areas or things like fuel lines from exhaust heat.

          Around the same time as these things were going in I ordered another pair of the ZR1 / GM export flares for the C4 chassis as well as an ALDL connector (looks like OBD-II connector).

          After a couple of tries at ordering via part numbers we finally received the correct ALDL connector for the 1994-1995 "Pre-OBD-II" connector port.

          That was wired in to the ECM at the computer, then the connector mounted to the side of the dash on the passenger side. This port will help with tuning in the future, as well as checking CEL codes.

          SCCA Club Trial & PDX, MSR-C, May 8, 2016

          The next event we could sign up for that allowed us to test the brakes was this SCCA Club Trial and PDX event at MSR-Cresson. The weather was pretty poor and it rained off and on that day. Somehow we got almost no pictures of the two cars we brought, and the video camera I brought had a dead battery, so I got no video. I did get some dry laps in several sessions and the brakes were rock solid.

          This was a combined PDX (HPDE) and Club Trial (Time Trial) but they didn't post any results. I asked for my times recently and they gave them to me - best of 1:24.3 in traffic. Out of 26 in Club Trials the Corvette posted the 3rd fastest, out paced by a Wolf (prototype) and TT3 M3. I ran a bunch of 1:24 and 1:25 lap times that day. The SCCA Club Trials events here aren't quite like what NASA runs, and the field has "a full range of talent". So traffic with 26 cars on 1.7 miles was as bad as you could expect. It was cold, rainy, cruddy weather. Still, I ran the car in 4 sessions and the brakes felt perfect.

          I instructed that day and rode through with 3 different people, including Brad from Vorshlag in 2 sessions, an S550 Mustang racer for 2 sessions, and Amy for a session. Made good progress with my two PDX students and Amy dropped 4 seconds per lap in the 330 after some coaching. She was on the 245mm Dunlop street tires so the lap times she ran we're relevant to our times on Hoosiers.

          I had that "Brake... Brake... BRAKE!" moment riding with Brad on one lap, hehe!

          I didn't want to abuse the fresh Hoosier R7s so after fighting traffic most of the day I skipped 2 sessions and put the Corvette back in the trailer after confirming that the pedal effort was good, the balance worked, and the brakes were reliable.

          I had planned on racing the car in the next few NASA race weekends but that just didn't ever happen. After the car was painted it was just too damn pretty...


          After this May test event the car sat for a week then I decided to skip the NASA @ Hallett event in June and get a jump start on the paint work I felt the car needed to be able to sell.

          The first step was to remove all of the decals from the car. Brad, Jon and I took turns and used low setting on the heat gun to soften the adhesive and pulled each one off without issue. Well, except the driver's door, which was entirely wrapped. It had some paint damage when we bought the car so Jon had wrapped that entire door in white film. More paint pulled off as this sheet was removed - Not a worry as this entire door would get reworked professionally at Heritage.

          We pulled all of the rear plexiglass hatch off first, then the roof skin. This roof panel was black but I wanted to see it in white, so that would be prepped for paint work by Heritage.

          Our local glass guys at Titan came by to remove the front windshield, which waited in my office for 2 months during the paint work.

          Then the side view mirrors came off, padding from the cage was removed, seat and ballast box were unbolted, and all the nets came out. We cleaned the car and loaded it into the trailer for the trip to Heritage in Sherman, Texas.

          Because this was a super busy time for them - 2 hail storms this Spring have had the body shops for 100 miles loaded up all year - I told them this was no rush. This way they could take their time and fit this admittedly lower paying paint job in between more lucrative insurance hail work.

          The front bumper cover was never pretty but they managed to rework the nose nicely. This portion of body work made a huge difference in the end and I'm glad they spent the hours there.

          The driver's door was a donor from another C4, installed many years ago, and it had existing damage and didn't match the rest of the car. They still managed to rework the fiberglass skin and get it looking smooth as glass before paint.

          The rear bumper cover also needed some love, but they got it sanded down, smoothed out, primed and ready for paint.

          The roof panel was sanded and smoothed, then primed before paint. Many hours were spent smoothing the hood and other fender panels, and of course the ZR1 export flares were bonded to the fiberglass, reshaped, smoothed, and integrated before being primed.

          The roll cage took many hours to sand, wash, tack and prime, then paint. The interior and cage were painted separately from the body, but both received several base / clear coats of Siemens paint in GM Arctic White - which has no pigment, just white base. It is the brightest white made and it really POPS when you shoot it with a high gloss clear.

          I picked the car up in mid August 2016 and was blown away. It looked... way nicer than I had hoped for. The price was less than it should have been, but still a good chunk of cash. I had the car painted to help increase the resale value and I think we got more than we bargained for...


          Pictures simply do not to this paint job justice, and the pictures look GOOD. On a sunny day the brightness of this car is dangerous... #DANGERZONE

          After getting a few shots of the freshly painted interior and exterior outside, we brought the Corvette in for the final list of updates.

          I had a few things listed that I felt were necessary to "complete" my vision of this project.

          That open "storage cubby" area behind the seats always bugged me, so I asked Donnie to make an aluminum panel to cover this and match the flat rear deck floor height. With some fiberglass-specific nutserts added the panel can be unbolted quickly for access to the ABS hydraulics behind the driver's seat. There's room for the battery on the other side but we decided against relocating that for now.

          continued below
          Last edited by Fair!; 11-09-2016, 06:40 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


          • #35
            Re: Vorshlag Budget TT Build: Project DANGER ZONE

            continued from above

            The passenger floor always bugged me with its bumpy OEM shapes so I asked Donnie to make a pattern and then make a 2-piece false floor for this side. The front section can unbolt and the rear section sits under the weight box. Looked good.

            Ryan made the reinforced false floor for the driver's side, which you step on to get in and out of the cage on that side. We will add grip tape for the buyer when they arrive to pick it up - just showing off the shiny aluminum for now.

            The gaping hole in the passenger side of the dash was where the factory airbag was located, which was removed long ago. The open expanse looked awful and I wanted an aluminum dash cover to be built on that side. The marked up picture (above left) was all Ryan had to go on.

            As usual Ryan thought farther than I had on the design and made it a 2-piece assembly. The upper portion mounted to the dash bar with rivets along two seams - bolts on the leading edge would be inaccessible with the windshield reinstalled. The lower section was removable with bolted hardware and nutserts installed into the upper section and along the sides.

            Of course you don't want shiny aluminum up by your eye line for glare reasons, so these two panels were removed and painted with many coats of texture black paint. Many coats. The picture above right shows this in place before the windshield was reinstalled, but the vinyl portion of the dash had some conditioner sprayed on to soak into the stock material, which was later buffed off to a dull haze.

            As well as the masking was done during the paint job, there was a hint of overspray in some areas and a couple of spots at the cowl we told them to leave in the stock black. These areas needed some prep and touch-up, so Brad masked off the freshly painted bits and prepped the areas that got some semi-gloss black paint.

            Even the underside of the hood was cleaned and detailed, with the OEM colors and plastics shining like the day it rolled out of the factory. The difference here was amazing, but ate up 8+ hours of cleaning, prepping, painting, unmasking, and more cleaning.

            After detailing the underhood area, the Corvette looks better than new, without a hint of over-spray and just enough gloss on the plastics to make my inner neat freak happy. This damn thing is too pretty for me to race now.

            One of the things I debated for weeks on was over reinstalling the quick release fire bottle or adding a full fire system. It was deemed more costly and not what some people want, so I will leave a fire system up to the next owner. This is all the car needs to go Wheel to Wheel racing, by the way. Well that and updated belts (they are FIA Cobra/Schroth 6-point belts, but expired). The original reinforcing plates were shined up and installed, then the Drake quick release bracket and HalGuard 2.5 pound fire bottle were put back in place on the tunnel.

            The stock steering wheel with the airbag removed was always a HUGE eyesore, and it made for a cumbersome ingress/egress with the cage installed. The diameter was so large that it blocked my sight line to some of the factory gauges.

            I ordered the MOMO Model 88 in 350 mm diameter, and initially got it with the wrong 6-bolt hub adapter (p/n 2702, for GM telescoping column). We figured this out quickly and reordered the MOMO 6-bolt steering wheel hub adapter, part number 2401. This is the correct number for a C4 Chevrolet Corvette with standard GM tilt column, which we kept intact as it makes for easier adjustment for different drivers.

            The new wheel really made a big difference, right? We had originally looked at adding a quick release steering wheel adapter but with the smaller diameter wheel and the tilt column its actually pretty easy to get into and out of the car with the steering wheel attached. I will leave a quick release up to the next owner, as these come in a variety of styles, thicknesses, quality levels, and prices.

            Of course the rear hatch, the seat, the belts, nets, and SFI padding were all reinstalled. Some sections of wiring harness were secured and tucked better. All sorts of little odds and ends were made perfect before the final "for sale" pictures were taken. This was both fulfilling and painful. On one hand I loved to see the C4 finished like I had always envisioned. On the other I knew I'd never get to race the car again - it was just too perfect now.

            For now this works, and the interior looks really finished, and it better shows the work we do. Unfortunately it is with a car that most folks don't associate with Vorshlag, and that's where the problem lies...

            FOR SALE TIME

            After all of this work over the past 2 years - getting the car fast, reliable, safe and looking good - it is time to sell it. Why? Like I said, this C4 Corvette isn't really a car that we see all that often at our shop. Maybe its the labor rates we charge, or the lack of competitive C4 race car entries right now, but this car isn't really representative of the customer work we see. And I need to be racing in the types of cars our customers own and bring to us. Like how a new BMW dealership wouldn't field a 25 year old Honda race car, you know?

            Would I prefer to keep this car and race it? YES! Its one of the nicest cars I have ever owned, now that it is finished and painted. Damn the "marketing", I'd love to run this car in 2017 in TTC class or even TT4 with a few changes. But being a small business owner there are always expenses I have to plan for, and this car needs to fund some purchases that I have to do to keep Vorshlag moving forward.

            It really sucks how these things happen... our E36 LS1 Alpha car was really fast right before we sold it, but it had to fund many things in our business in 2009 when it was sold. Likewise in 2015 when we sold our TT3 Mustang. I damn sure wanted to keep it, but that sale paid for a big chunk of one of our new CNC machines, which the business really needed. This C4 has a lot of time and money tied up into it and with as clean and perfect as it is now, it would be crazy for me to run it another season.

            This car is ready for a racer to jump in and go to the track today. Be it Time Trial or even Wheel to Wheel (with 2 small updates), it is ready to go and do so reliably. I put this For Sale Page up this week and I hope you go there and look at all of the pictures we have there. The price might seem high to some but I couldn't build another one like it for twice the asking price. That's just the reality of a fully prepped race car built by professionals - quality costs money. Any help you readers can do to spread the word is appreciated. I am sharing this same link on Facebook as well.

            WHATS NEXT

            It is going to be tough to say goodbye to Project #Dangerzone, but hopefully someone will appreciate all the work we have done and buy this C4 soon.

            Once it is sold I will update this build thread and hopefully share what we have planned with those funds - its a big step for our business, if I can make it happen. Until then this Corvette will wait in our shop until it finds its new owner.

            Last edited by Fair!; 04-05-2017, 08:19 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


            • #36
              Re: Vorshlag Budget TT Build: Project DANGER ZONE

              Project update for April 27, 2017: Not much to share for the past few months. We've tidied up a few loose ends and put the car for sale on an eBay auction. Let's catch up.


              After my last post I had the crew finish up a few things that weren't 100% perfect. One of the false floors was re-done in aluminum and it now looks great.

              One of my guys re-fixed the oil pan gasket and its finally perfect. Brad did a final clean-up on the Corvette and then I towed the car to my home shop, where it has been resting...

              There it has stayed while I got busy doing other things. We also found a lot of spare parts for the car when we moved it out of Vorshlag: new brake lines, belts, hoses, weatherstripping, a poly suspension bushing kit, and spare rotors, calipers, and another matching set of 17x9.5" SSR wheels. It all goes with the car!

              Last year I had put up a classified ad on the Vorshlag website, then we moved our website and all of the old links went away. I finally re-did that last week and made a Cars for Sale page as well - which has several Vorshlag cars (some completed and some "donor chassis") as well as a few customer cars we built.

              7 DAY EBAY AUCTION

              I wasn't in a huge hurry to sell the car as I was still unsure about our other shop race car's future - this 2001 BMW 330Ci. It was struggling to win in 2016 and I had some doubts as to its ability in TTD class for 2017...

              Well we finally spent the time needed to add power to this BMW and in 2017 it has been breaking TTD track records each time it goes out. Still 2+ seconds off the TTC Corvette's times, but that's to be expected. So since we had a a new "record breaker" we just recently decided to step up the selling game on the C4.

              Yep, today is a big day on project #Dangerzone - I just launched the 7 day eBay auction. Low reserve, lots of bids in the first few hours. We'll see how this goes.

              Also have my house for sale (need more land to build a bigger shop on) - which is another thing that has been keeping me busy for the last couple of months, along with launching a 2nd business and running Vorshlag.

              Long story short - if you have anyone you know that might want this beautiful race car, please send them the auction link! Its legal for Vintage racing this year, too. I will update this thread after the auction ends.

              Last edited by Fair!; 01-10-2019, 09:04 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


              • #37
                Re: Vorshlag Budget TT Build: Project DANGER ZONE

                Project Update for January 10, 2019: A lot has happened with our 1992 Corvette since my last post. A failed auction, some flaky buyers, then more updates and repairs, a big delay, and finally a successful auction.

                Now the C4 is back in the shop for some final final upgrades before it heads off for a Vintage Road Racing career.

                "FINAL" UPDATES & REPAIRS (VERSION 2)

                After my last post and the eBay auction that went sideways (long story - I won't ever try to sell a car there again). But we had a few calls and in the Fall of 2017 an endurance racer and fan of the build came in, looked at the car, we negotiated a bit, and then we shook on a deal for the sale of this car at a respectable amount.

                Then he came back a few days later with a trailer and some buddies, they poked around the car again and pointed out a few small parts wear issues - a torn ball joint boot, a cracked suspension bushing, and a one wheel bearing with a little play. Little things that he said he could easily fix - and so could we. Normal things for a 25 year old car, none of which I noticed on track. But then he tried to use these things to knock $4000 off the previously agreed upon price. Of course this shady negotiating tactic didn't work, and I calmly but firmly asked them to leave.


                It was time to re-assess what group of people this car would sell to. The typical eBay auction crowd was the wrong type of user for this car. Most of the calls about the C4 were either folks looking for an HPDE car they could drive to the track (of which we have built a number of) or an endurance race team.

                Of course this car was too far beyond "street driving" with the gutted doors, no headlights, and a roll cage, but it could easily be an endurance race car solution with one or two tweaks.

                The 245/40/17 Hoosier R7s look bald when new, and the super short tire height always looked goofy on this car. So I did some searching and bought a new set of 275/40/17 Falken RT-615K+ 200 treadwear street tires, which we mounted to the 17x9.5" SSR wheels. This is a tire appropriate for either a dedicated HPDE track rat or an endurance racer.

                This tire update already made a huge difference in how the car looked, with a significantly taller tire height (the OEM size for this car). Also, it should always be easier to sell any car with a brand new set of tires, right?

                REPAIR WORK + REAR TOE LINKS

                The used car salesman tactics did show us a couple of worn items, which now I was going to fix. We went over the car with a fine toothed comb looking for anything else visibly worn or that had unwanted movement.

                In the end we found two ball joints that should be replaced, so I ordered new AC Delco parts and Brad installed those in February of 2018. These were relatively easy to source, and while the install was a bit of a pain, it was nothing we couldn't tackle.

                One front wheel bearing had the slightest hint of play, so a Centric replacement was ordered. The rest were originals, which are supposed to be better than the aftermarket replacements, so they were left alone.

                The long ARP wheel studs were pressed out of the old unit bearing and installed into the new replacement. This was then bolted onto the front upright with relative ease.

                Out back we could see some bushing wear on both lower camber arms. Again, nothing you could feel, but it was visible, so I looked for replacements. Instead of just ordering bushings or OEM arms, I looked for something better this time.

                I found this VetteBrakes tubular, adjustable arms with spherical ends. This option would not only replace some worn bushings but allow proper camber adjustment in the rear.

                These were ordered in Fall of 2017, then we waited almost four months for a batch to be built. I know how that goes, and by late January of 2018 these arrived and were quickly installed. I asked Brad to raise the front ride height also, which took out some rake and made the car easier to load onto a trailer.

                The rear camber adjustment range was pretty huge (it could get over -5° camber!) so we took the car to a local alignment shop we work with (and had trained to do custom alignments to our specs). I drove it there and we asked them to just zero the front toe (front camber/caster is a bit of a nightmare on these cars, with unique shims) after our front ride height increase and ball joint repairs. Then asked them to focus on adjusting the rear camber to -2° with a bit of rear toe in (this helps turn-in and corner exit traction). With this fresh race alignment in February 2018 on a Hunter laser rack, it was ready to race! Well... ready to sell.


                I asked Brad to once again clean up the car and shoot some new pics.

                He got several shots of the car on the new tires and new ride heights.

                Now to write the text and find a place to auction it...


                After that point I got stalled out on other projects and work. Shortly after the last update in this thread (Summer 2017) our house sold and we moved to a property a bit out in the country. By Spring 2018 I was frantically trying to oversee the much delayed construction of our new metal building on this property, then Brad and I were working on it 7 days a week doing finish out construction in May and June before a hard deadline for our shop move by June 15, 2018.

                We still had significant construction going on for months after we moved in as well. During the Spring of 2018 our BMW 330 TT4 car had been painted and quickly sold, we purchased a 2018 Mustang GT, and that kept us busy with new product development and testing, and on and on.


                This hectic time pushed the auction for the Corvette until we were in the new building and a bit settled. I finally submitted the auction to Bring-a-Trailer in September 2018.


                Well there were some delays out of my control, after trying to get some small edits made to the auction wording, but by mid December they finally got back to me and we timed the launch of the seven day auction. I set it so the auction would end the day after Christmas, December 26th. Hoping people would bid and watch the auction while on holiday break. In the end there were 408 BaT members who had signed up to watch the auction. #Strategery

                The auction started off slow and stalled out a bit in the first 6 days, but on the 7th day, in the 11th hour, in the last two minutes... all hell broke loose. Four bidders started going after each other and bidding strong for this car. Each time there is a bid in the final two minutes of a BaT auction, they extend the auction end time by 2 more minutes. Anti-sniping protocol. Of course our internet connection (ugh!) at the shop went down during the final 20 minutes of this auction, so we were watching it play out on the lone cell phone that had one bar of connectivity. Damn near gave me a heart attack!

                WHAT'S NEXT?

                The new buyer reached out and paid for the car, and we found out that he was a legit road racer who wanted to run the car in a SVAR Vintage W2W series. That group requires two things this car lacked - an FIA fuel cell and a battery kill switch.

                This past week we pulled the rear bumper cover, rear crash structure and fuel tank. Now we are having a custom fuel cell quoted, which we will install soon. Also going to install a Car Tek Battery Isolator with dual remote kill switches. I will post up next time showing the wrap-up of that work.

                Thanks for reading,
                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


                • #38
                  Re: Vorshlag Budget TT Build: Project DANGER ZONE

                  fabulous that it finally sold to somebody who i gonna use it for what it was built for


                  • #39
                    Re: Vorshlag Budget TT Build: Project DANGER ZONE

                    For those reading about those camber arms, VB&P is now defunct. Sadly. Banksi makes really good rear heim-jointed links for the C4, and usually has them ready to ship immediately. They are my go-to recommendation for C4 rear suspension.

                    Unfortunately, no VB&P also means no high-rate, height-adjustable monoleaf springs for C4s now. Supposedly Van Steel has acquired the molds and intends to start making and selling these. If that doesn't pan out, then C4 racers who want real spring rates and adjustable ride height and preload will have to go with coilover options. The ones I know of out there leave a lot to be desired in terms of the shock options. And the rear knuckle attachment ear gives some concern for breakage.


                    • #40
                      Re: Vorshlag C4 Corvette TT Build: Project DANGER ZONE

                      Project Update for April 23th, 2019: This will likely be the last post in this build thread, as the new owner picked up the 1992 Corvette April 18th after we completed the various updates he asked for - which grew in scope after the auction ended in January.

                      In all honesty I lost a lot of money selling this car at auction (we had too many hours and dollars into this build), but after two years of trying to find the right buyer, it was the best we were going to get. The new owner has a fleet of Corvettes, including several C4 road race cars, and we were happy he chose us to do the final safety gear upgrades on this one. He had followed this build thread for years, and was one of the bidders in a previous auction that didn't make reserve.

                      ORDERING A FUEL CELL

                      The C4 will be run in an SVRA series that requires an FIA fuel cell. This is a little unusual, as OEM fuel tanks for the past ~25 years have been crash tested and refined, so much so that many road racing sanctioning bodies no longer have a flat "fuel cell" requirement. In many cases the OEM fuel tank is better placed, oddly shaped, and crashes better than a trunk mounted steel can with an FIA bladder inside. But the rules are what they are, so we had to use a fuel cell.

                      The timing couldn't have been better. We have worked with a few fuel cell manufacturers' in the past but last December we ran into Pryotect at the 2018 PRI show. We talked to them at this show about making custom fuel cell cans and bladders, something we have found to be both challenging and expensive.

                      Pyrotect has a lot of really nice options for their new fuel cell division, which was located in Redmond, Oregon. The 3 main fuel pick-up choices incorporated Holley Hydromat, a baffled section with check valves, and an internal surge tank. The customer went with the baffled pickup with a Walbro GSS340 pump installed, as well as a 0-90Ohm fuel level sending unit (that would read correctly with the 1992 Corvette dash).

                      The plan was to ship them the stock tank, which they would strip, modify, and add an FIA-FT3 Certified 12oz Pyrocell Bladder to. Then the typical fuel cell filler neck/upper plate section with the fuel pump and sending unit. Pyrotect went the extra mile and powder coated the unit for us in black, too.

                      That was the plan, but first we had to send them the fuel tank. Getting that out of a C4 Corvette is "not fun", as removing the rear bumper cover and fuel tank is a 4+ hour job.

                      Of course the fuel tank was full of fuel, and it had been sitting for a while. So that had to be drained and disposed off. The tank mounts inside this aluminum rear crash structure and comes out as a unit.

                      Once this was out we power washed it and removed 25+ years of grime and dirt. Then cables and mounts that keep the fuel tank to the rear structure were removed, the fuel tank was pallet-ized, and shipped to Pyrotect.

                      It took a while but the fuel cell arrived, boxed up and protected by extra fuel cell foam. It looked great and was ready to go back into the C4.

                      FUEL CELL INSTALL

                      Once the fuel cell was here it was re-installed into the stock rear mounting structure. Which was easy - because it was the same OEM fuel tank going back in. Everything mounted easily.

                      Then this was mocked up into the rear of the chassis to see where we needed to trim some fiberglass to fit around some fittings.

                      A bit of Earl's push lock hose and some Fragola fittings were added to the AN -8 outlet, return and vent lines to the new fuel cell.

                      There were a few spots of fiberglass that needed trimming to clear the fuel sender wiring and some fittings we added for the fuel system. The cell went in and out a few times to get everything to clear.

                      With the fuel and vent lines buttoned up and connected, GM connectors were wired/pinned and connected on the fuel cell side to match the OEM connectors on the chassis for the pump plus the fuel level sending unit.

                      Then the new cell was installed for the last time. The small clearance issues were hidden under the factory fuel filler flap assembly, which was re-painted black (the metal base), reassembled, and installed.

                      After installation, we filled it with 5 gallons of 93 octane, primed, and tested for leak-free operation. Then it was time to put the rear bumper cover back together. Tail lights, side marker lights, etc.

                      That was wrapped up and a blank license plate was installed (NASA decal on one side, blank on the other). As you can see the filler cap access is excellent. Really one of the easiest fuel cell installs we have ever done - because it uses the factory fuel tank as the metal can.

                      BATTERY KILL SWITCH + NEW BATTERY

                      During the same period we mapped out the cut-off switch location (based on SVRA class regs), ordered the old school kill switch (also required), then rounded up some bulkhead connectors and cable.

                      The location was mapped out for the shortest cable runs, but with the best access by both corner workers and the driver. I had Evan recess the bracket between the A-pillar tube and FIA bar, so to not block sight lines to the side view mirror.

                      This is easy to reach from the driver's seat, especially on the way out of the car in an emergency. The bracket is made from aluminum with slots for stainless steel ties (zip ties are shown - which were only used temporarily). We installed the four stainless clamp connections for this bracket later.

                      The insulated bulkhead connectors were added at the firewall for the alternator feed plus the in/out for the main battery cable pass-thrus. The original positive battery cable attaches to one of these bulkhead lugs. A new heavy gauge wire was run all the way the alternator, terminated, covered in matching loom, and secured to the engine harness.

                      New 0 gauge stranded cable was run for the 3 connections at the kill switch, terminated, and adhesive filled heat shrink was added over the lug ends. Then these were connected to the bulkheads and battery kill switch with insulated boots added for each termination.

                      When we were cranking and running the engine to test the new fuel cell lines for leaks, we verified that the switch kills the engine and all electrical systems. The battery (purchased about 3 years ago) was having trouble cranking and after being on a charger for 12 straight hours and it would never get past 76% total charge. Bad battery. We replaced this battery on our dime.

                      FIRE SYSTEM INSTALLATION

                      The fire system install was pretty straightforward. The bottle was mounted to the false floor on the passenger side.

                      We mapped out the fire system nozzle placement. The requested SPA NOVEC system came with 4 nozzles, so we installed two around the motor near the fuel rails on each side of the engine.

                      Next two more nozzles were added around both sides of the driver.

                      The pull is on the dash next to the Tilton brake bias bar.

                      There can be an additional fire pull added to this system, if needed, but the customer was happy with the location and access.

                      NEW 6-POINT BELTS

                      The Schroth center net, the window net, and THE Cobra seat are all current for several more years. But the Cobra 6-point belts were out of date. It was left from our "big parts display lobby" days. It was new when we installed it in 2015, just dated.

                      We sell Schroth harnesses and we just added the "new for late 2018" FIA 2016 spec harnesses - the 3 most popular ones. All of the Scroth designs changed in December 2018.

                      We had the Schroth Enduro 2X2 FHR 6-Point Harnesses in stock, so those were installed. Of course the seat has to come out to access the mounting points, since it is so tight in that cabin. But it was in and adjusted before the buyer arrived.

                      CLEAN UP AND PICK-UP

                      Other than some final paperwork and cleaning, the car was ready to go the day before the customer was set to arrive.

                      Since it was raining off and on, Brad and Evan cleaned up the car inside the shop. The exterior, tires, interior, underhood area, glass and Lexan were all spotless when they arrived.

                      The spare parts and extras were boxed up and loaded, and of course it really started raining hard as the car was driven into their enclosed trailer. The customer and his son are in the Indy area and will be racing this car with SVRA vintage road racing starting later this season!

                      Thanks for reading for the past 5 years,
                      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