Vorshlag C5 & C6 Corvette Development + NewBalance and Rampage

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Re: Vorshlag C5 Corvette Development Thread

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Once the differential housing was attached to the transmission (above), then the torque tube could be reinstalled (below).



Below are pictures of the hydraulic throw out bearing and the Keensert installation tool, for this thread diameter and pitch.



With everything bolted together once again it was time to raise the transaxle + torque tube assembly back into the car.



That all went back in place and the rear subframe then went in below that. The exhaust went on and we were ready to drive it.



One other thing that happened while the Corvette was here that week were new front ball joints. The old ones were cooked (likely from brake heat + age). Toe was realigned of course. We changed the rears as well.



Mark had also upgraded the front brakes to the AP 4-piston fixed motorsport calipers and 2-piece AP rotors, from their "sprint" kit, shown above. The rear brakes stayed intact.

Test drove the car and the synchros seemed even worse in this "rebuilt" M12 than the worn out MM6 trans that we removed. Mark came into town and drove it and he noted the same thing - it was a hot mess. So out came the M12 trans and I took it our local Tremec specialist (Joe D) for an inspection. Joe opened up the trans and called - it was a mess inside. It needed everything from synchros to gears, shift forks to bearings, seals and blocker rings. Took some time to source all of the parts, but $2300 later it was rebuilt and ready to go back in. At least this time there weren't stripped threads and bolt heads that needed to be cut off - it went in painlessly and quickly.

The race team that sold him this M12 owned up to some of the unreported damage, and I think Mark worked out some partial refund? The extra R&R work - since the transaxle had to come out again, get rebuilt, and be reinstalled - ended up as twice the normal install labor, plus the extra price of a rebuild on top of that. The C5 was also sitting for about 8 weeks while the trans was rebuilt then reinstalled, which sucked for Mark (no racing) and for my shop (storing the car for 2 months). Moral of the story is - always assume any used parts you buy need to be completely rebuilt!



With the fully rebuilt M12 transaxle now in place, the Corvette was back racing in March. The new 1st and 2nd gear setup worked SO much better now, with 2nd gear speeds that are much more usable. The only time 3rd gear is needed are on GIANT autocross courses, which we sometimes see at Mineral Wells Airpark events - like the 2016 CAM Texas event and the 2016 Texas ProSolo (see below). At every other normal course, however, 2nd gear is the only gear needed and slower speed corners have more usable torque on corner exit.

MGW SHIFTER

In May 2016, Mark wanted to improve the shifting of his car further so he ordered an MGW shifter from us. MGW shifters are made in the USA and the owners are super cool folks who road race regularly.



Mark and his co-driver Chase managed to install this shifter in the C5 and ever since it shifts even better than before.



With the long shift knob and the short throw shifter combined, the total shift throws are very manageable, the effort is low, and the "reach" for the knob from the steering wheel is a lot closer. Its a perfect shifter setup for this car.

2016 AUTOCROSS TESTING

In an unusual move for me, I have raced in 5 SCCA autocrosses this year, all in various CAM class cars. I ran Scottish Joe's 5th Gen Camaro twice and Mark's C5 Corvette 3 times so far. I fought GM's ABS system "ICE MODE" programming at all 5 events, and it frustrated me a great deal. How isn't this more of a thing? Why does GM suck at programming their ABS schemes? The Ford ABS is light years better than the Corvette or Camaro ABS. When I brake hard the ABS on these cars often "freaks out" and just stops... stopping. Pedal turns to a brick and I blow through a gate or cone wall.


2016 was the year of Cones and ABS Issues for me?

I'm also pretty rusty when it comes to autocrossing, probably since I haven't done much of this in the past 4 years, but its coming back to me, bit by bit. Its tough for me to jump around in other people's cars, and my "cone count" is higher than it has been in years. I'm either ICE MODE'ing the brakes or clipping the cone bases (like above), so don't take my results and videos as an accurate portrayal of how these cars are handling - a faster driver can always make these cars look better.

2016 TEXAS CAM CHALLENGE - MAY



Event pic and video gallery: https://vorshlag.smugmug.com/Racing-...CAM-Challenge/

Vorshlag was an event sponsor for this CAM Challenge event as well as the Texas ProSolo, so since I was gonna be there to cook for people anyway... I found co-drives at both events in some of our testers' cars.


Three Vorshlag test vehicles all running in the Texas CAM Challenge

We were still testing a new setup on Joe's car and at the CAM only event, when it had fresh 305mm Hankook tires and new 19x11" wheels, where it still had a bit of a push.



You can see the understeer we are fighting in the video above. One more event after a front spring change and more camber and we could have this one really dialed in.



3800 pounds of fun and came in 2nd out of 19 CAM-C cars (with our shop manager Brad coming in 8th in the same car) at the 2016 Texas CAM Challenge, and damned if I didn't run the time to win in the brackets, but coned it. I lost in the Saturday runs by 1.4 seconds to an old friend and Vorshlag tester Brian Matteucci in his white 2015 GT, shown above.



Mark and co-driver Chase were mired a good ways back in the CAM-S class, driving the C5 and fighting with "dead" tires. They were about 4 seconds slower than what we ran in the Camaro, which shouldn't be the case in an 800 pound lighter car. All year BFGoodrich kept running out of 315mm and 335mm Rival-S tires, and this was one of those periods where the C5 was shod with "compounded out" tires (I think they had 200+ runs on them at this point).



No major changes were made to the Corvette before the next event, other than fresh 315mm Rival-S tires were mounted.

2016 TEXAS PRO SOLO - JUNE



Event pic and video gallery: https://vorshlag.smugmug.com/Racing-...Texas-ProSolo/

I have co-driven Mark's Corvette three times this summer: At the Texas ProSolo in June, at an SCCA event at Lone Star Park in July, and at another regional in August. We are loaded up and heading to the 2016 SCCA Solo Nationals right now, too. I will give a brief overview of these 3 events so far in 2016.

2016 Texas ProSolo: https://vorshlag.smugmug.com/Racing-...Texas-ProSolo/

This was a fun event where I got to run the C5 in the merged CAM class for the Pro. Once again I was chasing Vorshlag tester Brian Matteucci's 2015 Mustang GT. Brian runs a Forgestar 18x11" CF5 wheel, 315/30/18 Rival-S, Vorshlag camber plates, GT350R springs, Eibach swaybars and a Torsen T2R diff with 3.31 gears - all of which we supplied to him. Brian is brutally fast in this S550.



I kept fighting with the ABS system's "ICE MODE" and my best right side run had a cone after when the brakes simply stopped working in one corner. Sure, I can "brake less" and not engage this glaring fault in the ABS programming, but damn it you shouldn't have to drive around these issues in all GM cars. Why can so many other car makers program their ABS systems to work with a wider range of grip and brake pad compounds without issue??



At this ProSolo Brian and I were paired up in the final 4 runs, and while I edged him by .3 sec in time overall for both sides, he beat me by .3 sec in the paxed times. The Corvette was really loose on corner exit at this event, and with the hectic nature of ProSolos (you run 2 left and 2 right side runs back to back) there isn't time (nor are you allowed) to change shock settings between runs.



Come to find out later, the rear shocks were set at an incorrect amount of compression, and we didn't catch it until after my runs were over. No wonder why it wouldn't launch well or put power down on corner exit. My runs were filled with lots of little driving mistakes, and I didn't have a single 4 run grouping without a major ABS brake system failure and subsequent "cone binge". I could not reprogram my brain to brake more gently than I am used to in autocross situations. The S197 Mustang ABS system ruined me, I guess? At least a Vorshlag tester took the win and the top 5 out of 7 in CAM were Vorshlag test cars once again.

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Re: Vorshlag C5 Corvette Development Thread

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SCCA at Lone Star Park, July 30, 2016

Event pic and video gallery: https://vorshlag.smugmug.com/Racing-...-Park-July-30/

At this SCCA regional event Mark's Corvette had 3 drivers - Mark and Chase drove it in CAM-S while I jumped up to "X" class to run it in a different heat. And heat was the key word - it was 97°F during my runs and I forgot to bring my cooler - which led to heat exhaustion that day pretty badly (2 other people at this event went to the hospital that day, from the same effects). It hit me so hard that day that it has crept back and got me another 3 times this summer. I'm really trying to stay ahead of it by drinking lots of water and Gatorade type drinks, but heat is really killing me this year.



You can't see it as much in the in-car video below, but I was fighting the ABS system in all of the big braking zones once again. This run the ABS completely goes bonkers on me and I blew 30 feet off line. The GM ABS is really starting to spook me - I just cannot use the brakes as hard as I can in a Ford, BMW or Subaru. Frustrating.



The handling was much improved with proper rear compression valving set this time, and my raw time was pretty good on my 3rd run, but I clipped a damned cone again - just ran over the base. By my 4th and 5th runs my hands were shaking badly, I slowed down, and I knew I was in trouble with dehydration. That run heat took almost 2 hours and there was nowhere to hide from the relentless sun. By days end it was 104°F and I was close to throwing up. After the Corvette loaded in my trailer and I sat in the truck for 30 minutes with the AC on full blast, trying to regain control of my brain, with a pounding migraine from the heat exhaustion. I somehow got home, then drank a lot of water and passed out by 5 pm and slept for 14 hours. I felt terrible the next day, my whole body hurt. This was a bad day.



My results in the "X" class were marred by my 3rd run cone (4th and 5th runs are thrown out in "X"), so I was somewhere near the bottom of the class. Mark and Chase ran in CAM-S a later heat but were about a second behind my best clean run. The rear tires were really giving up the ghost that day. They have been racing the car every other week all summer on this set, ever since the ProSolo, and did a huge number of runs on the rear tires. After this event we all decided the rear's needed to get bigger, so talked about an 18x12" rear wheel and 335mm tire for the remainder of the season.

SCCA at TMS Bus Lot, August 28th, 2016



Event pic and video gallery: https://vorshlag.smugmug.com/Racing-...t-TMS-Bus-Lot/

This was last weekend's event, but the day before I was at Motorsport Ranch running baseline track times in my wife's 2013 FR-S. I got overheated and was feeling sick Saturday afternoon. On Sunday at the autocross I was already starting "behind" on my hydration, and heat exhaustion kicked my butt again on Sunday. This was getting ridiculous.



I made a point to bring a stocked cooler with waters and Gatorade drinks and kept one in my hand all day, drinking non stop, but the previous day's damage was just too much to un-do. It wasn't even that hot, only about 90°F when I left at 2 pm, but I was feeling it while driving. I hit a record 6 cones over 5 runs in Mark's car that day, fought ICE MODE on every run, and had arguably my worst drive of the year. Right before Nationals, yay...



This layout was what I call a "busy little Miata Course" - as are all of the courses at Texas Region events - but that's what we had to navigate in this car. Mark was ahead of me all day, and I just couldn't seem to get ahead enough on the courses or stay off the cones. I am not even showing my in-car video, its just awful. Mark, however, drove very well and put .425 seconds on me that day and pax'd top 20.



We both felt the recent changes (see below) of new swaybars and wider 18x12" wheels/335mm tires made a big improvement out back. Mark's run above shows the Corvette doing so much better in corner exit than ever before.


Running on fresh 315F/335R Rival-S tires, 18x11/12" wheels, MCS TT2 coilovers, Eibach bars, August 2016

The MCS TT2 coilovers and new swaybars have improved the turn-in massively, and the roll/lean was visibly lower in head-on shots. Compared to the first time I drove the car on "good" tires, at the Optima event in 2014, its a night and day difference. That (below) was on 295/315 Rivals and Koni shocks with stock springs and bars. The new setup (above) has wider and sticker 315/35 Rival-S tires, yet radically less roll/dive/lean.


Running on 18x11" wheels, Koni dampers, stock springs and shocks, and used 295F/315 Rival tires, April 2014

So Mark was feeling good when we loaded up the Corvette that day, but I felt like crap again. And this was our last test event before heading to the 2016 SCCA Solo Nationals. I agreed to this months ago, but now I'm heading back to Lincoln for the first time in 4 years on a "low" for the season. I've gotta get my head in the game and stay hydrated next week in Nebraska. CAM-S is no joke at the National level. If anyone reading this sees me in Lincoln without a bottle of liquid in my hand, tell me to get some water!

ABS FIXES? SWAYBARS + WIDER REAR WHEELS & TIRES

After the July event and before the August autocross we brought the car back to Vorshlag for some updates. After the August event we installed fresh front tires on the C5, in preparation for the Solo Nationals. I will quickly show that here.



The aftermarket swaybar choices for the C5 aren't all that great, but we had supplied Mark's dad's C6 Corvette with an Eibach setup earlier this year. They were adjustable at both ends of the car and nicely built. So Mark wanted a set of Eibach bars for his C5. We ordered the C5 versions (no good pictures exist) and they showed up... non-adjustable. Oh well, they are tubular and larger in diameter, and Donnie installed them here with grease zerks and fitted the bushings to the bars so they can rotate (endlinks removed) with "pinkie effort". That's my rule on swaybars - no bind in the body mount bushings is allowed. Drilled, zerked, fitted, and greased every time.



When I won a single BFG tire for my 2nd place finish at the ProSolo driving Mark's car I donated the winnings to Mark - it was his car, after all. We requested the Rival-S in a 335/30/18 size and rounded up two more 335s after they had run out of stock this summer (thanks for the hookup, whoever you were), which arrived the same day as the wider rear wheels.



Earlier this year we saw some long lead times on custom Forgestar wheels, but this summer the wait times have shrunk as they invest in higher stocking levels of wheel blanks. A pair of 18x12" F14 wheels were custom spec'd rush ordered in "raw" finish (that can save you as much as 3-4 weeks) and mounted with the new 335s out back.



The 18x12's have way more "poke" that I would ever spec for anyone, but Mark finally broke down and said he's commit to flared fenders - at all 4 corners - after Nationals. So we really ordered these 18x12" wheels for the front, but will use them on the rear for Nationals. Forgestar confirmed to me on the phone yesterday that they finally have 18x13" wheel tooling and these wider blanks should be arriving in October time frame. So the rears on this car will go to either 18x13" F14 or 18x14" M14 2-piece Forgestars. The car might switch autocross classes, too.




The 315/30/18 Rival-S has been on backorder for many weeks as well, so we did some searching and Mark bought this set of 4 wheels and 4 new 315s mounted but never raced. Two of these became the "National set" of fronts.



Running race compound brake pads makes the wheels dusty in a short time. One autocross and the red wheels look black (above). One of the things I'm always giving Mark grief about is how dirty he lets the Corvette get. He doesn't care - clean doesn't mean fast - but I keep reminding him that the giant "VORSHLAG" decal on the side means that I do care. So every time it is in my shop we seem to be cleaning it...



We found a trick to cleaning metallic brake dust off of powder coated wheels years ago - a German chemical cleaner called "Sonax wheel cleaner", which I have mentioned here before. We have been ordering this stuff online and it is a bit pricey. Now there's a cheaper USA-made alternative called Code RED, which you can find at Pep Boys stores for about half the price per ounce. It uses the same chemical process that reacts to the iron particles in brake dust, which changes color from green to red once the process is finished. This must be washed off before it dries, and sometimes it takes two coats and some scrubbing, but its the best stuff I've ever seen for cleaning brake material off of wheels.



Another pet peeve of mine with this car for the past year has been the unpainted front bumper cover. We replaced this when his previous co-driver had a big "off" and tore up the nose, but Mark wouldn't let me get it painted then. This time, as a condition of my co-drive, I insisted.



Our friends at Heritage Collision Center in Sherman, Texas did a fine job and painted the nose and licensed plate cover back in body color. They had to do a bit of bodywork, as the unpainted nose took a lot of bug hits over the last year which damaged the surface. It looks as good as new now.



Jon here at Vorshlag made some fresh "class/number panel" decals for the side and they classed up the car a bit from the hand cut tape decals (oiy!).

WHAT'S NEXT?

We worked on some other things this summer, some of which are not finished, and I will talk about them after we readdress them after Nationals. For now we have the C5 as "ready as it can be" and loaded in the trailer. I leave for Nebraska tomorrow, picking up Mark along the way. I have no idea how we will do at Nationals, but I haven't been in 4 years and it will be fun to be there racing, win or lose.

Vorshlag is also sponsoring the "Nationals Winner" jackets for all of the "supplemental" classes: CAM-C, CAM-T, CAM-S, and STP / STPL. These are all classes I feel are too important to ignore, and we have pushed the SCCA hard for two of these classes to be created (namely CAM-S and STP). I will do a write-up after Nationals and talk about the other systems we have been working on, as well as talk about the new autocross classing plans Mark has for this C5 in 2017.

Cheers,

[Fair!]

Re: Vorshlag C5 Corvette Development Thread

Project Update for September 11, 2016: After returning from the 2016 Solo Nationals I had a pile of work to catch up on, so I worked all weekend and then sat down to do my post-event write-up. It will be brief as we haven't done any work on the car since returning, and Mark still has to decide what class to run next year: CAM-S or SSM. I don't have anything poignant to say about 9/11, even after being at Ground Zero a handful of weeks after this terrible event (it was still burning) - other than to say "I will never forget". I also lost a family member while I was at Nationals, and two others from the CAM/Optima community passed away during the same week, so that's been a bit rough.



There were some potential rules updates in CAM that were discussed and I will go over what was proposed at the Town Hall Meeting during Nationals. I drove pretty poorly and finished just outside the trophies, 7th out of 21 in CAM-S. Pretty disappointed in that, but the C5 ran solid and "coulda been a contender" with a better driver. Even with all of that we both still had a LOT of fun at Nationals this past week and I'm glad I went. It has been 4 years since I last attended - too long - but the fresh outlook of CAM is what brought me back.

Photo and Video gallery: https://vorshlag.smugmug.com/Racing-...olo-Nationals/



I usually take hundreds of pictures during my trips to Solo Nationals, but I had a bunch of stuff on my mind and just didn't take a ton this time. My wife Amy is usually with us and also snaps pics, but she didn't have a car to race this year and stayed home to work. The photo gallery above only has a little over 100 pics, mostly of the CAM cars, but also a few oddities we noticed during our 5 days in Lincoln.

THE DRIVE TO LINCOLN

Most people don't live in Lincoln, Nebraska, so the vast majority of the 1350+ competitors at this year's Solo Nationals had to travel to this very centrally located event site, where the SCCA has held Nationals for the last half dozen years. For some folks (on the coasts) the trip spans days of driving or a transport service and a flight, but we brought Mark's Corvette up inside my trailer with our Ford F350 towing flawlessly. This truck is by far the nicest vehicle I own and has more horsepower (400) than any of my current race cars, which is kinda sad.



From Vorshlag's Plano, Texas location, the trip to Lincoln was about 640 miles, which should take about 9-1/2 hours with no stops. I had to stop in Edmond, Oklahoma, to pick up Mark. Luckily that was almost directly on the way North to Nebraska. I left my house at 6 am Sunday hoping to get to the event site, unload the Corvette, and unhook the trailer before dark.

We grabbed some breakfast in Oklahoma and kept driving north. Once we got into Kansas we drove for hours across this vista of corn and windmills, then we had a blowout on the trailer. GRR, I hate trailer tires, and replaced all 4 of them after I had 4 blowouts on the way too and from Miller for NASA Nationals in 2013.



I know why this happened. Where I park my trailer on my property two tires are shielded from the sun by trees, but the other two (right side) get baked. I was suspicious of these two dry rotted tires before we left, but after replacing two front truck tires my "trailer budget" was pretty slim, so this blowout wasn't a huge surprise. We stopped within seconds of the tread cap coming off so it didn't do any damage. We installed one of two brand new mounted spares in a handful of minutes, and were back underway. #500psi



Not 10 minutes later I got popped by a cop doing 63 in a 50 zone. I was really being careful not to speed, because I hate getting speeding tickets in these flyover states, some of which are known to fund their municipalities with speed traps. The Kansas and Nebraska highways have lots of changing speed zones, going from 70 mph to 55 mph and back again, quickly and seemingly at random - there's nothing out here but fields of corn!



The rest of the trip was uneventful, other than pulling into a Kansas fuel station to be greeted by the bare ass of CP competitor Jeff Stroh mooning us as we pulled up to the truck stop pumps, LOL! We saw lots of fellow autocrossers traveling to Nebraska, of course. We arrived on site in Lincoln by about 5 pm Sunday and managed to unhook, unload, and get the Corvette through tech in less than 2 minutes (no line yet!). We also checked in at registration before the lines got too long on Monday. We parked 3 trailers from Texas racers in a circle to shield us from the unrelenting wind and inevitable rain.

MONDAY - TOWN HALL MEETING, CAM RULES, PRACTICE, & WALK-THRUS

This was Mark's first Solo Nationals but I had been many times and understood the schedule. Monday is always when the Town Hall Meeting is held, which is one of the only times the members get to speak with the BOD, SEB and Advisory Committee (AC) folks face to face. I am not a huge fan of the way that rules get made, and have sent hundreds of letters to the SEB over the years, so I show up at these when I can.

After a politically motivated shit storm following the 2012 Solo Nationals, I had walked away from the SCCA for the past 4 years, vowing to never build a car around SCCA Solo rules again. I've stuck to that plan, which has made my life easier. I do miss the challenge of Solo and as you have seen here in this thread, have dipped my toes back into the SCCA Solo scene in the past year. It was the brave new world of CAM that brought me back, so I wanted to go to the Town Hall to hear what was on the horizon for this category - to make sure that this set of classes stays as "un-SCCA" as possible.

After some introductions and opening remarks by the SEB, they open the microphone to racers that want to bring up questions. Several sad pleas from SSR racers (this is a "throw-back" Super Stock class that still runs Hoosiers, that is quietly dying), and some talk about a potential revival of Street Prepared category with some "too little, too late" rules updates (this once popular category is also dying), we broke up into groups where the AC's met with members to talk about rules and trends at tables spread across the tent area.



The wind was howling and felt like the tent would blow away at any minute, so we had to almost yell to be heard from 5 feet away (see video above). The "rules czar" of CAM, Raleigh Boreen, met with the interested CAM racers. We had a good discussion about the 3 existing classes. As many of you know, CAM is a very new category for SCCA, isn't (and may never be) "Nationally recognized", and the somewhat unlimited nature of the rules falls well outside of SCCA norms. That's why I like it - this isn't some 5 decade old category with old and busted rules, entrenched racers resistant to change, and is almost completely devoid of the politics that wrecks many classes over time. There is no "committee", which is probably why CAM has only one page of rules for 3 classes.



Still, there were some concerns voiced by a few racers. "Money in racing" is always brought up, and the "have nots" always want an equalizer. Luckily that was largely ignored in this "builders class", so we moved onto other details. The existing rule for "+150 pound penalty for Lexan front windshields" was discussed, argued, yet most folks missed the point entirely (double pane safety glass windshields are safer, and side and rear Lexan windows are not a safety issue). Raleigh reigned that in and we moved on.



So CAM is pretty simple: domestic front engine/RWD cars, some wheelbase limits, 200 treadwear tires, limited aero, and a minimum weight are all that the rules really care about in CAM. But the minimum weight in CAM-S (2350 lbs) is way lower than CAM-C (3200) and CAM-T (3000). CAM-C (newer with ABS) and CAM-T (older w/o ABS) are for 4 seat cars, and CAM-S is for the 2 seat cars with a shorter allowable wheelbase and ABS is allowed. CAM-S was supposed to be for real and kit car Cobras, and they can weigh about 2350 pounds in stock form.

We lobbied to have the C4/C5/C6 Corvettes and Vipers added to the CAM category last year - initially asking for a 4th class called "CAM-SS" tailor made for these modern 2-seat domestic sports cars with a 2800 or 2900 minimum weight. We had hoped to keep this separate from CAM-S and the uber-light Cobras (and other CAM-S builds people can dream up, like tube framed ultra lights based loosely on some domestic car built in the last 115 years) and keep the min weight attainable without a tube frame build.



At this town hall, Mark and I brought up the 650 pound penalty that is added to C4/C5/C6 Corvettes and Vipers in CAM-S. So we plead the case for moving these cars out of CAM-S into a new class called CAM-SS, and leaving the older 2 seat Corvettes (C3s are popular), Cobras, and lightweight custom builds in CAM-S. Or at the least dropping the 3000 pound min weight for them in CMA-S. Not wanting to rock the boat, we just wanted to follow the original plan for CAM: Classes separated by "old and new" + "4 seat and 2 seat" guidelines. Some CAM-S racers didn't want this, yet they don't want to race against "superior chassis with ABS" like the C5/C6 Corvettes. Some even suggested moving the C3 Corvette into CAM-T, which most CAM-T racers vehemently argued against.



There were the "no rules!" folks, who oppose any changes, and a few weird arguments like "weight doesn't matter", arguing that the 2350 pound Cobras were somehow at a disadvantage because they were 650 pounds lighter - which I openly scoffed at. A handful of racers in CAM agreed that the 4th class, CAM-SS, would be best to move these modern ABS equipped cars away from the existing CAM-S classic cars. Hopefully this is the only change that comes of this Town Hall meeting, as the rest of the ideas just went in circles and didn't fix anything. Closing the 650 pound penalty in CAM-S still allows for the "crazy" builds but lets the more abundant C4/C5/C6/C7 Corvettes a place to race on a level playing field. Ultimately it is up to Raleigh, and he said he was aiming to have the 2017 CAM rules posted early - by November 1st or Thanksgiving at the latest - to give racers time to adjust for any tweaks to this new class.



So we will see what becomes of that and Mark will decide where to take the C5 next soon after. SSM allows some big aero and of course Hoosiers. CAM-S has street tires, no aero, but seems more fun. And there are "damned rotaries" in CAM!



The practice course is running most days during Nationals held on a separate part of the site far away from the grid and main course areas. The Nebraska Region SCCA runs the practice and it sells out weeks or even months ahead of Nationals. Mark thought ahead and bought a 4 run pass for us to use to get familiar with the concrete surface and maybe make some small changes to the car.



We ran this on Monday before the Town Hall, with our 4 runs slotted from 2-3 pm. The wind was powerful and blew over the timers every couple of minutes, so in the 5 chances we had to check out the course we got no times on 4 of those. I got a somewhat lackluster time on my "sighting run", the first shot at the course either of us took, on cold tires. Instead of sticking around another hour trying to get re-runs on the 4 "no time" runs, we just packed it in and "saved the tires". I've made drastic changes based on runs from previous Nationals Practice courses and it always bit me in the ass. The car felt a little pushy, and we adjusted tire pressures UP from our local asphalt courses to this grippy concrete, but left the car alone otherwise.

The rest of Monday was spent sitting around waiting for the course to be open for walk. We roamed around and got stopped by dozens of people, even ran into Brett Madson, who was my pick to win CAM-C (and he did, by a good margin).



We walked the West course only, which was what we would be driving first on Tuesday. All of us scratched our heads at the unusual way that the course was marked. It was dominated by 3 cone clusters and cone walls, which I felt would lead to a lot of lost DNFs and cones (it did). On our first walk through we would find the #500psi cone, which was one that got pounded the most on this course.



Bret's SN95 Mustang is pretty much a maxed out CAM-C build. It has a 2-valve 4.6L V8 that makes 380 whp (???). It is built light and has hundreds of pounds of lead in the rear frame rails, so that helps the front-to-rear bias greatly. It has a built T45, he runs 335 mm Rival S tires at all 4 corners, and uses modern Watts Link and decent spring rates. Nothing exotic, easily attainable, just one of the first folks to really build for CAM-C. He also drove his ass off and won the class by nearly a second.



We ran across a lot of funny stuff in the paddock, like the fully furnished tent with hot tub in one area. The "Taco Truck on Every Corner" golf cart. Lots of wild SM cars with giant tires - a friend asked me to take pictures of the Subarus in SM, so you will see lots of 315mm and 335mm shod Subies in the gallery.



The BRZ below left had a neat GoPro video camera mounted to a tow hook at the front, which I thought was a novel idea. This was one of nearly 150 of the "86 twins" that filled STX and CS classes. CS had 86 cars and STX had 72 entries, both with a very heavy BRZ/FR-S contingent. Giant freakin classes!



After a long day of activities on Monday we headed to the hotel to check in. Mark had a room at a fancy Marriott downtown he got on hotel points, which was really nice. This was the first time I had stayed in a hotel in "The Haymarket", which is the downtown high end hotel, food and bar district. It is always where we end up going to eat during Nationals, and it actually makes sense to stay there if you are going to eat there - other than the F350 barely fit inside the parking garage.

continued below

[Fair!]

Re: Vorshlag C5 Corvette Development Thread

continued from above

We ate well in the Haymarket district restaurants with a different group of racer friends each night: Buzzard Billy's had decent Cajun food, BurgerFi had a great burger and onion rings, and we had some good grub at Lazlo's.



I didn't get much sleep that week, however, as a certain somebody who's room I shared snored like an unmuffled rotary at full revs. I stayed up and watched the F1 race, surfed the interwebs, and listened to music on my phone until there was a break in the sound, then I would doze off and try to start my side of the snoring battle. With 1-2 hours of sleep each night it began to catch up to me, but I managed to drive "about like I usually do" through mild sleep deprivation.

TUESDAY - DAY 1 - WEST COURSE

Tuesday morning bright and early was already hot - damn hot - and breezy. Sunday, Monday and Tuesday were all sunny days with ambient temps in the 95°F range each day, so I made sure to drink plenty of water and consumed most of a case of Powerade that week. Always with a drink in hand, trying to stay out of the sun, and slathered in SPF50 sun screen when I needed to walk course or stand in grid. I managed NOT to get heat exhaustion or sunburned all week, which was a major accomplishment for me.



It was super busy that morning, and I was assigned course work during heat one for FP, GS and STX Ladies. The West Course kept us hopping and the 1.5 hours flew by quickly. Then we waited for one heat in our paddock before another course walk between heats 1-2 and we gridded up in heat 2.


Day 1 run 3, Terry driving terribly

I didn't bring my good camera with us to grid on Tuesday so all of these pics are from Wednesday on East course. The in-car video above is my 3rd and final run from this West course, which kicked my ass. It was hard to see and I got caught out with mistakes on every run. Mark and I both had trouble here, as did many others - even the designer for the West Course coned every run on his own course.



I stayed off the cones, but probably too far off. I was driving too conservatively, always seeming to get on throttle too late, turning in too early and getting "behind" on the cones in every section. This made for some slow times, which seems to be par for the course lately for how I've been driving in Mark's Corvette. Which is a shame, because the car was working beautifully! I managed to stay out of "Ice Mode" on the ABS, which seems to be less prevalent in this car on concrete than on asphalt. It is still there, but just harder to achieve.

There was a 3rd gear shift necessary in the final section before the finish that I struggled with. In my 2nd run I was going for 3rd and hit a bump, which popped my visor halfway down, and the bottom edge went right across my vision. I was blind for about 3 seconds, so I reached up and popped the visor down so I could see, then when I looked up again I was 30 feet offline and about to plow down some cones. My first run was crap and this nearly aborted run matched that time, so I went into run 3 with nothing but junk. It was more of a "safety" run than anything, trying to be clean and salvage something for day 2.



Mark had issues on every run and his 1st attempt ended up being his fastest. He started off well but just never got faster, which always hurts. I think we were both caught off guard at the higher grip levels available on Rival-S tires on concrete, as neither of us had any experience with this tire on this type of surface. Both the OKC and Texas Region SCCA events are all held on asphalt - we lost our last 2 concrete lots in Dallas 2 years ago - and it shows. We kept trying to push ourselves to go faster, but the tires always seemed to have more in it.



Serious autocrossers will travel to Lincoln to run the Spring Nationals and even some of their regional events before Nationals, and we should have done that. But Mark was still dabbling in SSM on Hoosiers earlier this year, and I had no intentions of taking anything to Solo Nats, so we just went up more on a dare than anything else.



CAM classes: CAM-C had 27 drivers, CAM-T had 11, and CAM-S had 21. After the 3 runs were over for day 1 we had both fallen to mid-pack, 11th and 12th out of 21 in CAM-S, and almost 2 seconds out of the lead. That night someone told us that a cone was found for another CAM-S competitor ahead of us, so we moved up to 10th and 11th. Not a good place to be heading into day 2, but I was doing the rain dance and hoping for a miracle - which is what we would need to move up significantly.

WEDNESDAY - DAY 2 - EAST COURSE

We didn't walk the East Course until the end of the day on Tuesday. I won't walk the 2nd course in a 2-course event until after the 1st course is done, to keep my mind clear. We walked this one again Wednesday morning.



This course flowed better and was much easier to see. I enjoyed this course better even with the wet and dry conditions.



I worked course while Mark worked Impound, and the skies looked pretty bad in first heat. The entire heat 3 was CAM cars but we got a few STX drivers to help us work on Day 2, to balance out the worker load. I got paired up on corner with the head of the STAC, who had some great comments about the Street Touring category - which I watch closely and raced in for 5+ years (STU) starting back in 2005. We stayed dry the majority of this heat but it started to sprinkle at the beginning of 3rd runs, and really started to rain in the closing minutes.



After heat 1 we went back to the trailer to stay dry and the rain came down hard in heat 2. C-Prepared was running and the wet conditions really shook things up. I was hoping for a continuous light rain, to keep course wet but still driveable. It stopped raining about 30 minutes before we needed to head up for heat 3. That's right when my sister called and told me our father had died. This was a huge shock and it messed with my head. A lot. I had to drive in less than an hour so I tried to wrap my brain around driving, visualizing the course, and thinking of ways to catch up some time versus other CAM-S drivers.


Mike "Junior" Johnson's flared C3 has LSX power, giant Rival-S tires, and weighed in at 2934 pounds. He took 3rd in CAM-S

The grid area was sopping wet but the rain had stopped as CAM gridded up for heat 3. There were substantial puddles on course, mostly on the right side... which was the start and finish areas. The rest of the course was still wet but the wind and sun were drying things quickly.


Richard Jung's CAM-S 1968 C3 Corvette also has LSX power and tips the scales at 2950 pounds

I went out first (I was 99 to Mark's 199) and it was still very wet, but I pushed the car hard trying to set an early quick time. I hit the first cone in the first slalom but had a decent raw time. A number of other driver's had cones on their first wet runs, too, but Mark managed a clean and faster run in the later part of the first runs - he was the last car to take the course for CAM-S each time, being # 199. This moved him right into the trophies, so we had some small hope there.

Run 2 was getting dry on the left half of the course but still sopping wet on the right. I dropped 3 seconds into the 69.0 range but again, hit the same cone in the first slalom. I wasn't even aware I was hitting it but the cone sheets don't lie. Mark went even quicker with a 66.5 time on his 2nd run, solidifying his trophy position around 5th place now, even better.



We go into run 3 and I am sitting on cones and I really need a "hero run" - finally clean and much faster. All of the CAM drivers are dropping several seconds per run as the course dried out, and the 2nd drivers are seeing even drier conditions than the 1st. I was the final "1st driver" to take the last run on West course and I gave it all I had. I dropped another 3 seconds to a 64.102 second run, which felt incredible. If the video would have worked for our last runs I would show it... it was precise, faster, and I felt good about it. This run moved me into 5th and final trophy spot as I came across the line, and I gave a hoot and a hollar!

Mark had the driest look at this course in CAM-S, and he dropped 1.6 seconds to a 64.917. But by then the 2nd driver CAM-S times had dropped into the 63 and even 62 second range, so he fell out of the trophies and down to 11th. At the end of heat 3 my 3rd run was the 6th quickest in class, but I was too far back from day 1 and finished 7th of 21, one spot out of trophies by .277 sec. Here are the Official Results.


Shawn Lambert and Eric Brown took this 2002 C5 Z06 to 1st and 5th in CAM-S class on BFG's... this tire took 1st-12th in class

WRAPPING UP, EXPLODING AIR BAGS, AND PASSING ON

We went back to our paddock spot, a little down but glad that one of us could catch up a few spots. Mark said he was happy with finish in his first ever Solo Nationals, but I'm never happy with anything other than 1st, hehe. We went to lunch as the sun came out, which made the site a humid and wet mess, grabbing some mediocre Mexican food and plenty of water. We had time to kill before the banquet, which was slated from 5:30 until 10 pm.



After our 2 hour lunch break we came back, loaded up the Corvette and packed the trailer for the drive home Thursday morning. We got cleaned up at the hotel, made it to the banquet hall early, and talked to dozens of folks. Right as the "banquet chicken" lines opened up for the Tues-Wed banquet, we eased our way out of the hall and again went to the Haymarket for Indian food at The Oven, which was amazing. We ran into some Texas Region SCCA folks and shared a table with them.



Thursday morning we hooked up the F-350 to the trailer and said our goodbyes. Apparently there was a MASSIVE rain storm some time after we left - 2 inches fell in 20 minutes - and some associated controversy over the event stopping, some drivers getting dry runs before/after the rains, etc.


Texas Region's Feras Qartoumy built this 72 Nova at home, but "don't call it the Murder Nova"

As I write this at least 5 classes are still under protest or appeal, but eventually that will get that sorted out. I do dislike the "some wet / some dry" runs in the same heat, but its Nebraska in September - IT ALWAYS RAINS.



Keith Lamming in CAM-C had an unusual thing happen to him on course: airbags exploded. This is a known issue in the 2010-11 5th Gen Camaros, where high grip slaloms will trick the car into thinking it is going to crash and the curtain airbags deploy. Keith said he normally removes the air bag fuse before any autocross run but simply forgot this time and it "did what they all do" in autocross. This isn't a thing on 2012-15 5th gens, apparently.



Long time Optima racer Todd Rumpke passed away early during the week of Solo Nationals. He was 53 when he lost his battle with cancer last week. There was a big tribute to him at LS Fest this past weekend where Danny Popp drove his C6 Corvette in competition. I remember Todd from when I raced against him at OUSCI. The news hit everyone hard.



Tony "Rosco" Rietdorf was at Solo Nationals and ran the CAM Challenge in his SN95 Mustang. Sunday night after the Challenge he fell off the back of a golf cart in paddock and his head hit the concrete. An E.R. doc was on the scene within seconds but Tony was unresponsive. The EMTs arrived quickly and he went to the hospital where they induced a coma to reduce brain swelling. There was a GoFundMe page created to help pay for his medical costs, which is still up. We got news last night that he passed away. So sad that a freak accident in the paddock could claim the life of a 36 year old so quickly. Just sucks.

I also lost my father the same week. Its complicated... but I didn't have much of a relationship with him, nor did my sisters. Still sucked hearing this news, which was unexpected. Throat cancer took him at age 75.

And on that positive note... let's wrap it up!

WHAT'S NEXT?

The "drive home from Nationals" always ends up where massive bench racing and planning happens, and this exercise is fun. I dreamed up no less than 4 cars "I need to build" for the 2017 season, two of which were CAM cars, but the reality is that... maybe one of them will get funded and built. I've got the manpower and the know-how to do more, just not the budget to build a fraction of what we can dream up.

There are some plans for Mark's C5 still in process, which I'm not allowed to talk about just yet. I was going to bring his C5 back to Vorshlag after Nationals but Mark had an OKC autocross the following Sunday (today), so I dropped it off at his place and we will get our hands on it sometime in the near future.



The pending rules changes (or not, we shall see) in CAM might prompt Mark to stay in CAM-S. If either the 650 pound penalty for C4/C5/C6 and Vipers goes away or they move to CAM-SS, he might stay in CAM. Otherwise he might move over to SSM and play with Hoosiers and aero. We shall see sometime in November when Raleigh releases any new rules for CAM. I will write up another entry here when we know more, or when get to play with this C5 - or another C5/C6 - in the future.

Thanks for reading,

[Fair!]

Project Introduction - August 2nd, 2017: For some time I have been meaning to create a "development" thread for C6 generation Corvette (2005-2013), to show the parts we have built for and work we have done to these cars at our shop. On July 27th I purchased a 2007 C6 Z06 chassis, so I needed to start a "C6 build thread". Instead of two separate threads this will function as both. From time to time here I might also touch on some C5 and C7 Corvette work, as those generations are similar enough to the C6 that there is some crossover.



We purchased this C6 Z06 chassis for a number of reasons. Like to develop things like a proper roll cage for this aluminum chassis, to perfect some new wheel fitments, to test out new engines/components, and eventually to build it into a dedicated road race car. But it is meant to be a test platform for our own and partner manufacturers' products as its first priority, just like all of our shop owned cars.

Potential Snowflake Trigger Warning: In this thread I will not be "self censoring" the contents, to make it more palatable for cross-posting into multiple forums like I usually do. Why? Well to be honest most of the car tech forums where I used to share threads on are either dead, broken, have become pay-to-play and just full of shills, or have so little traffic it is not worth the effort. This is written for the Vorshlag forum, but if there are some remaining car forums that are looking for uncensored tech, it will have: water marked pictures, links to products on our website, and rambling posts covering multiple cars. For the first time in 15 years this will be a raw, no-holds-barred post. Easily triggered readers - this thread is not a Safe Space! Remember: I'm not putting a gun to your head and making you read this.



This build and development thread, like everything we do, has the end goal in mind of improved road course and autocross performance, along with additional horsepower. Those are the things we care about are: turning, stopping, and accelerating. We won't be discussing car show upgrades, or stereo tweaks, just things that make a C6 better in competition motorsports use, building/fabricating parts, testing and driving these cars on track.


Left: The C7 Corvette uses an aluminum chassis like the C6 Z06. Right: C6 Z06 on 315F/345R Hoosiers + aero

I will open this first post with the reasons why I have NOT had a C6 Corvette for the past 12 years, then we will cover some basic aspects of the C6 chassis that are noteworthy. I will then veer off into a 2016 track test where I put some laps in a stock '12 C6 Z06 vs a '17 C7 Grand Sport (and a '13 1LE) to get a baseline lap time, which we can compare against when we drive other modded C6 Z06s on track (including our build, some day). Then I will cover the rolling chassis 2007 Z06 we purchased. I will also show some other C6 Corvettes we have worked on and developed parts for in the past several years. I won't cover everything C6 related we have done in my first series of posts today, but will instead insert the various C6 parts and past work into future posts.

SELF-IMPOSED C6 OWNERSHIP BAN

So I initially wrote an eleven paragraph section explaining the reasons why we sold our 2005 C6 Z51 12 years ago - a car that I absolutely loved for its performance - and then I waited until 2017 to buy another. Other than for my own benefit nobody would have cared to read those 11 paragraphs, so I re-wrote that to be extremely brief.

In 2004 my wife saw the C6 at a car show and loved it. We custom ordered a 2005 Corvette Z51 6-speed with no other options, got it within the first month of the C6 debut, drove the heck outta the car for a year, and really enjoyed it. We autocrossed it a bit (on 11" wide wheels with 315 Hoosiers) and that car and I really clicked. In the words of Jim Carrey: "I like it a lot."



After a year of ownership we came to a cross roads: we were building a new house/shop, Vorshlag was just starting to take off, and since the main product we sold at the time was spherical camber plates for McPherson strut cars it didn't make sense to own a Corvette that couldn't use these parts. Since the C6 was brand new and cars were still very scarce we sold it for what we paid for it. It was a tough call but selling that C6 really helped us move Vorshlag forward in 2005. As a result I have been racing "McStrut" cars almost exclusively for the last 12 years. A dozen years of waiting... for another.

WHAT MAKES A C6 CORVETTE WORTHWHILE?

I'm not a "Corvette person", or a devotee to any marque or model. I don't go in for any "car worship", but instead value a car for simple reasons: power, handling, brakes, grip, drive-ability, and weight. I don't really care what badge is on the outside, what "prestige" a car maker has, as long as it delivers the goods. Part of our business is making "hybrid" cars using things like a German chassis, an aluminum GM LS engine, Ford differentials, brakes from South Africa, suspension from Holland, etc. We try to take the best "performance/price" parts from all over the world and put them into one car.



The C6 Chevrolet Corvette happens to have a lot of really good "parts" all in the same chassis, from the factory. And the Z06 model is amped up even further: hydroformed aluminum frame, *carbon fiber bodywork (*some panels), ample tire room, 7.0L 505 hp aluminum V8 with *dry sump oiling (*only a 2 stage pump, but better than a wet sump), decent brakes, and a low drag body shape. It runs low 11 second quarter miles and can do 200 mph top speeds in stock form. The strong, rear mounted transaxle (see below) shifts some weight to the rear, which is always good on a front-engined car. Its relatively light, too.



There are some negatives as well - poor seating position/visibility & limited interior room (making racing seat and cage installation difficult) to name two. Having a composite body that bolts to a full frame is supposedly less efficient than unibody construction. Is that last claim proven? We have a good test in mind to prove or disprove this unibody vs full frame weight theory.

We will compare the final weight of my 2007 C6 Z06 race car build (below left) against a similarly prepped, carbon roof/hood equipped E46 M3 (below right). Both builds are getting large displacement aluminum LS V8s, both will have a 335mm front and 345mm rear tire, both will be caged, and both will get similar aero upgrades. In the end the scales will show which is lighter and which has the better front/rear weight bias. I'm actually pretty excited to see both of these being built side-by-side in our shop.


Which V8 race car will be lighter? The body-on-frame C6 Z06 or the lightened unibody BMW E46 M3?

Every car I have purchased since 2005 has had some business purpose for Vorshlag: as test mule/product development chassis and usually as a marketing vehicle in some form of motorsports competition. I violated the first half of that rule (we don't make any C4 Corvette parts) when I purchased this 1992 Corvette below back in 2014 (Project Dangerzone) - which we built just to prove a theory. Turns out that hunch was well founded and we set several track records in the car, got noticed by NASA officials, and they threw weight at it the next year. Had a lot of fun with that C4 but there were some Corvette specific challenges we had to learn to solve, like the roll cage installation. Landing cage tubes onto a full framed car - while passing through a composite body - was tough.



We want to test our cage building techniques on this Z06 - a car with an aluminum frame, no less. We have seen some sketchy cages done on C6 and C7 aluminum chassis cars and want to see if we can come up with a better solution. So "better cage development" will be one of many goals for this chassis.

BASELINE ROAD COURSE TESTING: STOCK C6 Z06 vs C7 GRAND SPORT!

If you have read any of our other detailed build/development threads you might already know that we do a lot of track testing. From 2008-2015 we did most of our track testing at ECR, but that track has gotten too bumpy. For 2016-17 we have moved our road course testing to the 1.7 mile CCW course at Motorsport Ranch in Cresson, TX (MSR-C). I cannot exactly "baseline test" the 2007 Z06 chassis we bought, as it is in pieces, but I've got the next best thing.


Photo Gallery - Track Test, September 16, 2016: https://vorshlag.smugmug.com/Racing-...C-Test-091616/

On this beautiful Friday morning last September I was lucky enough to be able to drive three cars around MSR-C with an AiM SOLO lap timer and camera in each one. Same day, same track, same driver, similar tires. The first two included a 2013 Camaro 1LE that we modified (see this thread) and the same car owner's newly acquired 2017 Corvette Grand Sport 7-speed manual, which was bone stock and still sporting the dealer's paper tags. These were both owned by our tester Scottish Joe.



The Camaro was on fresh 305/30/19 Hankook RS-3 tires (on 19x11" wheels we spec'd) and the C7 GS was on fresh 285/335 Michelin Pilot Super Sport tires (factory equipped).



I also tested our accountant Jerry's almost bone stock 2012 "Centennial Edition" C6 Z06 Corvette, who has become a product tester for us on two cars now. The Z06 was on fresh 285/335 MPSS tires (same as what came factory equipped, same as the C7), plus it had better brake pads, some additional negative camber up front (-2.0°), but it was also otherwise bone stock.



We got there early on a member day and the weather was great in the morning. I managed to get out on course in the Camaro when the course was devoid of traffic - which made for some easy laps where I clocked off some quick ones. This car was on coilovers, camber plates, 19x11" wheels, aftermarket headers, dyno tune, Cobra racing seats and Scroth 6-point harnesses. The Cobra racing seat and harnesses made driving the big 3800 pound Camaro effortless and I wasn't having to "hang on" like I did in the C6 Z06 - which had some of the worst stock seats I'd ever experienced.

Data Logged Track Videos at MSR-C in Vehicles on Street Tires:
https://youtu.be/6Rpepzil8FI - 1:21.89 in the stock 2017 C7 Grand Sport
https://youtu.be/athEpfLRH3o - 1:22.56 in the modded 2013 1LE Camaro
https://youtu.be/1_B2u_fOnww - 1:22.63 in the stock 2012 C6 Z06
https://youtu.be/fpWyzzf-pHk - 1:27.40 in a stock 2016 Focus RS
https://youtu.be/Cs6AF436ykE - 1:31.90 in a stock 2013 Scion FR-S

All three cars I drove that day put down fast track times but each was very different to drive. The Camaro had lots of track specific suspension/brake/power/seat/tire upgrades, so it wasn't exactly a fair fight there. All of these laps listed above were in street going vehicles using 200-300 treadwear street tires and the same AiM SOLO lap timer / data logger and driver. This AiM unit is within 0.1 sec of the AMB timing loop whenever I run NASA Time Trial events here, too.



The Camaro's stock 14.5" Brembo front brakes were upgraded with custom brake cooling that we made, G-LOC pads, and proper Motul fluid. These were absolutely infallible - watch the g-traces in the on-board videos and you can see how I abused them (1.1-1.2g stops on every corner, every lap) and yet never had a hint of fade. The Hankook tires worked great, generating 1.3g lateral in some places, mostly 1.1-1.2g. The brakes on the C6 Z06 and the C7 GS both had larger 6-piston iron brakes with GM's "half measure" semi-directed brake cooling, but both were actually pretty easy to overheat - after my fastest lap in the GS the brakes had massive fade. The brakes were more manageable in the C6 Z06, but that was mostly the pad upgrade - I could overheat them as well.


Left: The C7 GS brake cooling is a "scoop and flap" method. Right: The C6 Z06 has a plastic brake cooling duct

The C6 Z06 had Carbotech brake pads (XP10 front and XP8 rear compounds) and better fluid, so it was stopping better than the C7 GS. Other than the brake fade tendencies the $76K Grand Sport was GLORIOUS to drive and the fastest of the three that day. For stock seats the C7's upgrades "sport seats" were pretty good, but still left something to be improved upon. The stock brake pads were complete junk, though. Its hard to imagine how GM could deem these track worthy pads - I could completely fade them in only 2 hot laps on this brake friendly course.



I drove my fastest laps in the C6 Z06 and the C7 GS with a passenger riding shotgun (nobody would ride with me in the Camaro, ha!), and since I drove the C6 last it was in the hottest temps of the day (94°F). It was still surprising that the C6 Z06 - my dream car - put in the slowest lap of the 3 cars I drove that day. Why? Well the stock suspension felt very soft and the car was rolling around like a school bus. The stock seats were downright awful - I felt like I'd slide up the door panel and pop out the side window on every big corner.

Both the C7 Grand Sport and C6 Z06 were on very fresh 285F/335R MPSS tires, so grip wasn't an issue. The C7 GS has different programming on the mag ride shocks and it seemed to corner MUCH flatter than the C6 Z06, which also had mag ride dampers. Again, the C6 Z06 was only 3/4 of a second slower than the C7 GS, but it definitely felt slower in the corners. Power it had for days, brakes were better as well. It was very interesting to drive these cars back to back in their stock forms.

continued below

[Fair!]

Re: Vorshlag C6 Corvette Development + Shop Z07 Race Car (Rampage)

OTHER C6 DEVELOPMENT

We have built some C6 parts and done track upgrades on these cars, which I will show in future installments of this development thread. Jerry's C6 Z06 has been going to the track 2-3 times a month for the last year so we get to see how pads, tires and such are wearing on his car.



Of course we weighed his 2012 C6 Z06, above. At 3217 pounds it is about the same as a base C6 Corvette, a touch heavier than the C5 Z06 (3050-3100 is common), yet hundreds of pounds lighter than Joe's C7 GS (below left, 3409) or the yellow C7 Z06 (below right, 3570) automatic we weighed. The C7 GS has a dry-sumped LT1 engine and iron brakes, with identical tire sizes, so its the closest C7 to the C6 Z06.



The C7 got a little bigger, a little more complex, and a good bit heavier than the C6 Z06. Its a bit funkier looking as well, at least to me. All C7 Corvettes have an aluminum frame and carbon fiber bodywork, too. The "non-Z06" C6 has a steel frame and fiberglass body, for what it's worth. My former 2005 C6 Z51 tipped the scales at 3150 pounds, with low fuel load, on a digital scale.

After that September 2016 track test I convinced Jerry to let us test out some better front brake cooling upgrades on his C6 Z06. This has helped extend his brake pad life on track significantly as well as reduce the chance of brake fade on track.



I will talk more about this C6 Z06 brake cooling kit when it is closer to production (we are testing version 2 now). Next time I will also show the Powerbrake 6-piston 350mm front brake upgrade kit we tested on Feras' 2008 C6 Z06, which he races in the Optima Ultimate Street Car series. I drove this car on track recently - which ruined me forever. Feeling how a heavily modded C6 Z06 handled on the same MSR-C surface was eye opening.



Feras' 2008 Z06 also just got a 7.7L stroker aluminum LS engine from our sister shop, Horsepower-Research. I will cover much more about the extensive list of upgrades on his Z06 next time.

VORSHLAG C6 Z06 - PROJECT RAMPAGE

So let's talk about this rolling heap of C6 Z06 parts I recently bought. This 2007 model Z06 was the innocent victim in an elaborate insurance fraud case and it ended up being confiscated. It was so mired in paperwork that the insurance company sent it to auction to be sold as parts.


Some Assembly Required

The damage to the actual chassis was minimal and it actually drove into the body shop I bought it from last year under its own power with every body panel intact. The title was a bit of a mess so it sat and sat, then parts started being "liberated" for use on other C6 Z06 body repairs. From the picture below left (taken 6 months earlier, when I first saw it) it lost the LS3 engine (part of the insurance scam - someone had swapped out the LS7), front fenders, right front inner apron, the hood, front nose, front bumper beam, driver's door, windshield, driver's seat, steering wheel, rear bumper cover, wheels, front upper control arms, rear toe link/tie rod, and both rear fenders. A lot of parts left this car...



It seems like there wasn't much left, and it would be nearly impossible to sell this to anyone who wanted to make a real street car out of this chassis. It didn't even roll. But I spotted it there when I bought another car from this same shop and told him to "Stop stealing parts off my C6!" Eventually I came back and bought what was left to make a race car out of...



I paid a little more than scrap value for this Z06, and honestly I am happy with the purchase. With 3 other race cars and a business to run, I couldn't have afforded to buy a $35-40K+ used C6 Z06 that was a complete car. And with what we have planned, it would be wasting a lot of good street parts. Brad and I fought with loading this car in 103°F heat, first getting it onto dollies, then pushing it into my trailer (of course the winch decided to die that day), then we hauled it back to Vorshlag. The whole crew here helped unload it - and once again they thought I was nuts! But I had a vision, and managed to negotiate for a bunch of spare C6 parts the shop had. We filled the truck and trailer with random body parts they donated to the cause - a hood, apron, a door missing the window, some rear fenders, random wheels, and a few other bits.



Once we got it here Aaron got to work getting the rear hatch open. With that unlatched we found the rest of the entire interior, minus one seat and steering wheel. So we'll sell those bits soon to recoup some costs.



We didn't waste any time and the day after we unloaded the car I ordered a new pair of front control arms and rear toe link from the Chevrolet dealership, to replace missing items. Aaron spent 1.27 hours and installed those new suspension bits, bolted on the rear fenders and driver's door, then he installed on the Z06 front wheels and tires we got with the car. It rolls!



Of course I weighed these parts before they were installed. You expected anything less?? There are all sorts of weights we took of various C6 body parts, which I will show in future posts.



Brad got a weight of the Z06 assembled. This is with all of the body panels and hood we got with the car, the full interior (minus the seat/steering wheel), and the transaxle/torque tube... but no motor, nose, or front fenders. We're pulling interior parts out now and will show more of this build up next time.

WHAT'S NEXT?

I wanted to keep this first post short and sweet, and its already grown a bit long. We have already started getting our Z06 lighter by removing unnecessary engine bay wiring, plumbing and reservoirs.



We have also started removing interior and the bolt-on roof panel (below left) in preparation for roll cage layout. The first set of race wheels is being measured for and ordered soon, as one of the "freebie" wheels we got with the car isn't exactly holding air (below right).



I will show more of this shop Z06 race car build-up next time. We don't have a concrete build schedule or detailed plan for it yet so I will share that as it emerges. We have 3 other shop race cars and plenty of customer cars that all need attention, so our Z06 will get worked on as time and budget allows. I will also explain the project name next time, but Archer fans will have already figured it out. #Zima

Thanks for reading,

[Mark-C]

Re: Vorshlag C6 Corvette Development + Shop Z07 Race Car (Rampage)

Hey don't forget the C5 autocross car in December doing a 1:22.5!!!

[V-lag]

Re: Vorshlag C6 Corvette Development + Shop Z07 Race Car (Rampage)

awesome build. Just wondering if you have new updates about the build?

[Fair!]

Re: Vorshlag C6 Corvette Development + Shop Z07 Race Car (Rampage)

awesome build. Just wondering if you have new updates about the build?

After a long search we found some OEM bodywork to replace what was missing on our C6Z chassis. The ZR1 front fenders and Grand Sport nose will be attached and fitted in the next 3 weeks, then I will make an update.

[Delor]

Re: Vorshlag C6 Corvette Development + Shop C6 Z06 Race Car (Rampage)

Incredible write up and log of the build!

[Fair!]

Re: Vorshlag C6 Corvette Development + Shop C6 Z06 Race Car (Rampage)

Project Update for July 9th, 2018: It has been a while since I first posted about this C6Z shop build but we have been moving forward with this chassis. I'm buried in new shop construction but will take a moment to try to catch up on Project Rampage.

THE SEARCH FOR CARBON BODYWORK

A lot of what I share in our build threads is done to help you, our readers, from avoiding the mistakes I have made in the past 34 years of wrenching on cars. Often I need to re-learn the same lessons I have learned before. This was one of those times. Being Cheap is rarely the right call.



Remember - I bought this 2007 C6 as rolling chassis and it was missing a lot of parts: the engine, both front carbon fiber Z06 fenders, one of the front inner fender composite structures, the hood, and the rear fenders were off the car - among other things. The OEM front fenders on the C6 Z06 are the only real carbon fiber parts on the C6 Z06 (the ZR1 has these + a carbon targa roof panel). The rest of the car is straight up "fiberglass" composite, but the C6 versions of the Z06/ZR1/GS also have an aluminum hydroformed frame - a first for GM.


Not many OEM cars can fit a 335mm front or 345mm rear tire with properly sized wheels!

There are two distinct sets of bodywork for the C6 chassis: the base/convertible "narrow body" and the Z06, Grand Sport, and ZR1 "wide body". The differences in the wide body front and rear fenders (and front under structures) allow us to fit MUCH wider tires on these C6 models vs the the narrow body C6. Like these monster 18x12" front and 18x13" rear wheels are on our tester Jerry's C6 Z06 shown above. This car has stock fenders and swallows 335mm front and 345mm rear Hoosiers. We have sold lots of wheels for C6 widebodies in this size.


These are the fender mods needed for an E46 M3 to fit the 335F/345R tires!

We are able to fit these with no body work whatsoever. Do you realize how hard this wheel/tire setup is to fit to other cars???? The E46 M3 above has 62 hours of custom metal work to clear these same wheel/tire sizes.

OEM C6Z WIDEBODY FENDERS?

I went looking for C6 widebody OEM fenders the WEEK after I brought this car to Vorshlag in August 2017. What were the parameters of the fenders I sought out? Well first was strength. The OEM ZR1/Z06/GS "wide body" fenders are very light but also very fragile - racers and mechanics complain of how easy it is to crack these just leaning on them doing underhood work. And the way I drive they might take a few "off track" excursions. So I wanted something stronger than the fly weight stock front fenders.


The only real "carbon" on the C6 widebody are the front fenders. VERY light... maybe too light?

Next up was cost. Wow, the OEM carbon wide body fenders are PRICEY! They can cost $2000/each new and even $800-1000/each used (+ shipping), and most of the used stuff is damaged even at those prices. So I looked at aftermarket stuff....

FENDERS WIDER THAN OEM C6Z WIDEBODY?



These "super wide" front fenders by Supervettes seemed pretty slick. These come in all 3 C6 widebody variants: the Z06, the ZR1 and the Grand Sport, and each of these had unique fender vents. After talking to their composites guy he said most people buy the ZR1 version, the Z06 is rarely chosen and only one guy has ever bought the GS style. I had considered buying their extra-wide Z06 front fenders at $1900 in fiberglass or carbon at $2300, but just couldn't make myself do it.



I had seen these in person - these fiberglass ZR1 style Supervettes fenders on the C6 Z06 above belong to the owner at the body shop where I bought my rolling chassis - but the rears looked almost ridiculously wide. Maybe I was just being too picky and cheap? The fit was good but they do take some work to fit to the chassis, and they are a bit heavier. And since tires wider than 345mm rears don't really exist, what is the point? This option seemed more "stancey" than "racey".

LOW COST ZR1 CLONE FENDERS?



Next up I looked one of our vendors who makes composite fenders, hoods, and complete body kits. This company has multiple names: Extreme Dimensions, Carbon Creations, and Duraflex are the main three we have dealt with. We used their Duraflex (flexible fiberglass) nose on the widebody E46 M3, shown earlier.



They make "ZR1" style front fenders (above left) had a hybrid C7 / C6 front nose (above right) that looked like it might be cleaner aerodynamically than the Z06/GS/ZR1 nose (their OEM front noses are identical and are made for the widebody C6 OEM front fenders). Their website was unclear if this C7 "stingray" nose fit the wide or narrow front fenders.



After months of deliberations and searching for used OEM wide body C6 fenders to no avail, I broke down and bought their "carbon" front "ZR1 style" fenders and this C7 look "Stingray" nose. Again, their website was vague as to which C6 models these would fit - they claimed wider than stock and that they fit "all C6 models", but was that wider than C6 narrow body or wider than C6 GS/Z06/ZR1 widebody? I had several emails and calls with them before purchasing these fenders, the nose and a matching lower splitter section (to make the bottom flat so we could build a real splitter from there) shipped by freight truck to our shop.



I am the first one to tell you that some import composite parts will not always work like they claim, but I needed to re-learn this lesson again. These front fenders simply do not fit an OEM widebody C6 chassis. Turns out they were made for the base model "narrow body" C6 chassis/nose and just look like ZR1 fenders. We would have had to cut giant chunks of the wider inner structure off to make these narrow body / narrower fenders "fit" our widebody C6 chassis. No thanks.



And even if we had done this modification, these were nearly double the weight of the OEM carbon fenders and - more importantly - at least 2" narrower than real ZR1/Z06/GS fenders, per side. Luckily my emails up front to them made it very clear up front that we needed as wide or wider than ZR1/Z06 fenders, so they allowed me to return all of their bodywork for a refund, minus shipping both ways (about $330). I figured the $330 was the cost of learning this lesson. They said they would update their catalog, to remove any confusion for others in the future. As of this writing I still have not found a cheap widebody C6 ZR1/Z06 front fender.


This Duraflex 6 piece flare kit for the 86 chassis is about $400 and easily covers an 11" wide wheel

Now I don't want to disparage this company (Extreme Dimensions / Carbon Creations / Duraflex) because their products to have a place in racing / car builds, and they have a MASSIVE catalog. Like I showed earlier, we used their 1M nose on an E46 M3, and I have recently purchased the Duraflex 86/FR-S/BRZ flare shown above for use on our shop 2013 FR-S. These bolt-on flares should easily cover the 18x11" wheels we have coming for this car, which should work well with 315mm tires and V8 power.

BACK TO FINDING OEM C6 WIDEBODY FRONT FENDERS?



After nearly 6 more months of searches, I came upon these used black OEM C6 ZR1 front fenders, shown above. They looked nearly perfect and the price was right (still cost 4 figures).



I also managed to score a free nose from a C6 Grand Sport - which needed some repairs but was easily fixed - from my painter friend Shiloh. With as tight as my budget was at the beginning of 2018 (in the middle of building a new shop, upcoming move, expanding our CNC machines), this was exactly what I needed.

LET'S SEE IF WE CAN HAVE SOME CARBON ZR1 WIDEBODY FENDERS MADE!

I was still worried about damaging these fragile, expensive OEM carbon front fenders on track, so I made a deal at the 2017 PRI show to send our C6Z chassis - with OEM bodywork attached - to a manufacturer who makes real carbon fiber parts, at affordable prices.



The deal was they would use our car to make molds for replacement front fenders, rear fenders, and doors (maybe some other bits) in carbon fiber, made for racing use - similar weights as the OEM rear fenders, lighter than stock doors, and as close in weight as the carbon fronts - plus stronger and more cost effective. This way, if I stuff the car into a tire wall I'm not out one hojillion dollars for new OEM bodywork!



Now i needed to get all of the OEM bits ordered and installed onto our rolling chassis, then arrange for transport to the west coast...

ORDERING OEM PARTS + ASSEMBLY

As I started in a previous post, I bought this 2007 Z06 chassis as a rolling chassis, partially disassembled. The body shop I bought it from took a complete car and started picking parts off to use to fix wrecked C6 Z06 cars that had rebuilt / salvage titles. Our car had a "parts only" title, due to a paperwork issue with an insurance claim, so it was impossible to sell to be used for street use. For a race car, however, its perfect.



They had taken the right front inner fender structure off of this car - which is a fiberglass piece normally bonded to the frame. It is a LOT of work to remove cleanly, and even more work to reinstall with the factory thick epoxy goo for a repair to another chassis. Essentially if you damage this piece in a crash, you should buy a new one from GM, remove the old one, bond in the new one with a 24-hour set epoxy, and temporarily install the rest of the bodywork to line it up right.



Well we got another widebody C6 removed structure from this car with the purchase - why they removed it is anyone's guess. Instead of bonding it to the aluminum chassis I decided to have it bolt on, which will make it easier to perform some of the underhood fab work we have planned. The C4 Corvette chassis (above) had a more accessible engine bay due to the large (and heavy) clam shell hood/upper fender sections, and bolting this inner section on will give us similar room on the C6 - albeit without the ease of just opening the hood.



It looks like whoever tried to remove the bonded inner fiberglass structure from this car damaged it pretty badly (see above) - there are big chunks of fiberglass still stuck to this frame. Those areas had to be sanded away before we could install the used OEM "widebody" inner structure we got onto this chassis.



Brad used a heat gun and some scrapers to loosen the epoxy goo and removed all traces of it from the aluminum frame rail. It took some patience and elbow grease, but eventually it was all removed - as well as the fiberglass fragments. With the aluminum frame rails now bare, we could attach the replacement inner.



We began by acquiring a gaggle of OEM parts to get this car put back together externally, to then ship the car to Anderson Composites in the first part of 2018 for molds. We lined up the fender liners, some front bumper cover support parts, the front bumper cover from a C6 Grand Sport, and the ZR1 fenders mentioned above.



Brad began fitting the right front inner fender support in late January - after we ordered some M8 nutsert parts and tools for some of the inaccessible parts of the frame. Some of the bolts we used to attach this inner were into "blind" areas, and some were thru-bolts, as shown above.



Bolting these inners on instead of bonding lets us shim them to fit perfectly, to get the fender gaps right.

continued below

[Fair!]

Re: Vorshlag C6 Corvette Development + Shop C6 Z06 Race Car (Rampage)

continued from above

These are the M8 nutserts - threaded inserts that install like a blind rivet - which we used to install the inner fender structures in some hidden locations. As you can see below, the factory used these in the same size in the bottom of the frame rails.



The ends of these boxed, hydro-formed frame rails are usually capped off and inaccessible on the inside, so bolts & nuts are not an option down in here.



On the exposed upper flanges of the frame rail (see above left) we used thru-bolts with nuts on the back side. With the additional holes drilled into the frame and inner structure bolted down the inner and fender were shimmed and fitted, so that the fender lined up with the door. We can unbolt this fender and the inner structure now in about 15 minutes for "deep access" to the engine bay, at least on this right side.



Once that right side fender was installed, the left front went on and lined up somewhat easily. Now it was time for the hood - which we got with the chassis purchase, from a red C6 - but first, we had to source stock hood hinges and repair the studs those bolt to at the frame.



These new OEM hinges above were able to bolt up to the two studs sitting on top of the frame rails after some minor repair. Whoever chopped the ends of the rails off left just enough meat in there to keep the studs, and one bent one was later reinforced and welded (see the "capped end" work below).



With the hinges loosely assembled to the frame rails, the hood was then installed. Then the hood and fenders could be adjusted to line up together and up against the front edge of both doors. We removed the factory hood latches and cable release at the firewall (heavy) and will instead use a pair of AeroCatch latches when we pick the final hood (won't be this red one).



Next up Ryan made a small aluminum support panel for the underside of the tear in the Grand Sport widebody front nose. This bumper cover included some of the OEM structural bits, so it was easier to line up the tear than a bare bumper cover itself. He bonded the small support panel to the underside of the flexible cover with epoxy and let it set up overnight.



The front section of the frame rails had been hacked off to repair another car - so instead of robbing another chassis of these ends ($$$) and painfully lining those up, I decided to just make a crash bar from aluminum tubing. I asked Ryan to clean up the cut-off ends of the aluminum frame rails, to square them up and make the ends symmetrical, side to side. He then made some flat plate sections to cap off the rails and TIG welded those to the cut frame ends. We will come back and bolt a tubular aluminum front crash bar to these sections later.



We sourced the crash bar tubing in 6061-T6 aluminum (above left) but we were tight on time (my shop cars pay the company $0/hour!) and Ryan had already lined up the nose structure to a bunch of additional brackets we sourced from GM (above right). So he was able to line up the front nose to the chassis without the crash beam in place (which we will definitely add later).



Next up a pair of used C6 headlights I sourced from eBay were installed. I looked for new units but they are 4 figures each - no cost effective knock-offs exist yet. These OEM units were $400 for the pair, which is unusually cheap for a complete set of even used C6 lights - but unlike the pictures online, these were all full of sand (?!) and had scratched lenses when they arrived. I should have known that the "unbelievably low price" meant they looked nothing like the pictures in the ad. What can I say - "typical eBay purchase". The nose was installed finally and everything lined up together.

TEMPORARY STEERING COLUMN

The stock steering column was removed (and the steering wheel was missing) when the interior was stripped. But soon we will need to steer this car on and off a trailer, for transport while the bodywork is being made. We have an electric assist column in the plans long term but we needed something - now.



I asked our crew to build this temporary steering column, shown above. In hindsight we could have just reinstalled the OEM steering column and just bought a steering wheel and hub adapter, but I wasn't ready to pick the steering wheel just yet, and the GM hub adapter wouldn't be re-used, so instead I bought $60 worth of parts above. It looks terrible, but will be tossed out when we make a proper racing column for the car later (just an OEM to 6-bolt hub adapter is $90 + a $250 steering wheel = this was cheaper for temp use).

LOTS OF OEM LIGHTS/GRILLS/SILLY BITS

After getting the car looking mostly complete, the guys at Anderson wanted to see more of the OEM bits if they were going to make a replacement nose in carbon. So I spent a couple of months chasing down all sorts of grill inserts, fog lights, turn signal / side lights, and more.



Valuable lesson learned here. So I did find knock-off fog lights, which are apparently damaged often enough to support this line of cheaper offerings. And the base C6 vs the widebody C6 look very different, yet all of the online offerings show the same part number. The parts above arrived and they look "wrong", so I paid to send them back and then bought OEM replacements from GM for 3x the cost.



Joke is on me - turns out the same foglight fits both the base and widebody C6 noses, even though the foglight openings are wildly different in shape. The larger "base" foglight shape is covered up by the widebody nose's opening. There is a carrier on the inside of the bumper cover the matches up perfectly to the weirdly shaped foglight. I never even thought to check the cheaper ones I bought online. Oh well, now I know. And no, these will likely never be used on our car in racing trim - just got these bits for Anderson to verify molds if they make the carbon nose replacement.



These side marker lights mount to the nose and I found knock-offs for the OEM parts, which I ordered. Annnnd that order was cancelled, due to lack of stock. So I sourced these from GM for 2x the cost. Another piece likely never to see racing use, just need for Anderson's checks if they make the nose.



Brad and I both spent some time with the heat gun, solvents and an eraser wheel on a drill removing some dried adhesive that was baked onto the paint. This was from clear adhesive backed film that was used to cover the open windows (which were there but the battery had been removed) and gaping maw of the missing windshield. This caked on stuff was a real pain to remove, but the eraser wheel worked the best - after the car was left outside in the sun to soften the dried adhesive. Cleaned up and ready to transport to California in late March!



We fought for two months with transport companies and in late May we finally found one that would 1) transport a non-running car, 2) would transport a car without a windshield (enclosed transports only), and 3) that actually showed up! Now the truck that arrived was an enclosed ramp truck had no winch, so it took 8 people to push it up the steep ramp into the truck. At least it steered and the e-brake worked. Anderson has the car now and should hopefully have it wrapped up and ready to transport back to us in July or August?

TERMS OF RAMPAGEMENT

It was a lot of months chasing down parts and re-assembling this car, but it was finally shipped out just before we moved our shop. But this car needed a name before it left...

Those of you who are not fans of the hit animated series ARCHER might be wondering why the hell are we calling this car "Rampage"?? First, go back and read the build thread for our C4 Corvette, Project Dangerzone. Notice the Archer themed jokes? If you don't watch Archer you are missing out on a lot of one liners.



In Archer season 2 episode 9 called "Placebo Effect", Archer gets cancer. When he discovers the chemotherapy drugs he's been taking for his breast cancer are counterfeit (sugar pills and Zima), he sets out to destroy the Irish Mob criminals behind the scheme. He goes on a "Rampage", killing everyone involved with the fake chemo drug ring... so pretty much how driving this Corvette will be like, right?



Expect to see ZIMA sponsorships (a tasty 1990s malt beverage), breast cancer awareness decals (legit), some taunts to the Irish, of course a few other Archer series nods on this car when it hits the track.



We transferred the "RAMPAGE" rear plate from the DangerZone C4 over to the C6Z. Along with adding a new the C6 OEM bumper cover (shown above) and some structural bits needed to mount it - all of which I bought from GM. Hoping that Anderson will also turn this rear cover into a carbon piece, but I doubt it. I'll be happy with all 4 fenders and both doors being carbon - anything else is a bonus. These parts are slated for production so everyone can buy them, once they are ready.

WHAT'S NEXT?

We are busy working on a number of other shop projects and lots of customer builds, of course. The shop move is done but construction continues, so I am kind of glad the C6 is at Anderson for another month or so.



Since starting on this C6Z we have painted, finished and sold my BMW E46 330 "daily driven track car" experiment (above left), so we were left with nothing to race. So in late February 2018 we bought this red 2018 Mustang GT (above right) and have already done two rounds of mods, lots of track testing, raced it in NASA and SCCA Time Trial events as well as an Optima series event. There are build threads for both of these on the Vorshlag forum, linked in this paragraph.



Meanwhile HorsePower-Research has been building these tall deck aluminum block 527" LS7 engines in ever crazier versions. Its the biggest LS engine in the world, at 8.6 liters! The 1/2" taller deck height on the RHS aluminum block is hard to even see unless you know what to look for. So we are thinking about using one of these for our C6 here. You can read more about some of the street car versions of this 527 that made 720 whp on E85 at this link. With some more advanced heads, a custom intake manifold, more compression (race fuel) and a conservative 8000 rpm power peak, it could sneak up on "four digit power". So... pretty much a Rampage.

More soon,

[Fair!]

continued from above

WHEEL MEASUREMENT SESSION

Wheels on this BASE model C6 are pretty narrow: 18x8.5" ET55 fronts and 19x10" ET79 rears. This is what we used to jokingly call the "drag pack" wheels for Corvettes back in the day, and why when we custom ordered Amy's 2005 C6 we made sure to get the Z51 package - which has wider wheels and bigger brakes, among other tweaks. Virtually all modern (C4+) Corvettes come with narrower front wheels and tires than the rear, to ensure "safe" handling - meaning UNDERSTEER. Lawyers are why most cars handle poorly, but that is an easy fix for us!



There are numerous 18x10" wheels out there that fit this car with a "Square" setup (same width front and rear), and even some 18x10.5" has been done. But our goal here was to measure a narrow body C6 for MAX FITMENT wheels. So Jason and I measured the car, using the stock wheels to go by, and our proven techniques to see what is the theoretical maximum wheel and tire widths on both ends. Then calculated the offsets and put a wheel order together.



What wheel brand and model will we use? What widths and offsets? Stay tuned and we will show you soon, after a set of custom 3-piece wheels arrive. That's right - this will not be another "Forgestar F14" wheel set for one of our cars, as none of their one piece, flow formed wheels can be built to the offsets needed to fit this car's fender limits. This is with another wheel brand we've been quietly working with, and I want to show off their work. It will likely be the most extravagant purchase for this entire project, but WHEELS MAKE THE BUILD.



We will make some suspension tweaks to be able to fit these but we WILL NOT be adding the C6 "widebody" fenders to clear bigger tires. Why? Well, after a lively debate internally, we concluded that converting a narrow C6 to the OEM widebody fenders takes a LOT of time and money - which could be better spent on the 3 other shop owned race car builds, not to mention the many customer builds that are demanding all of the hours we can throw at them to be completed.



And yes, the widebody C6 is my favorite car GM has ever built, so this was not an easy decision to stay narrow body. The wider C6 cars - Z06. Grand Sport, ZR1 - can fit SO much tire under the stock fenders! (see above) But again, our narrow C6 build will be pretty limited on scope and quick to complete, minimizing shop hours and costs. The narrow body C6 is also extremely undervalued and under appreciated in the (still flaming hot) used car market - we aim to see how far we can push one of these, on a budget.

C6 BRAKE OPTIONS AND UPGRADE PATH?

I learned a good bit from some recent research, including from this Corvette Forum post. The base C6 non Z51 has the JL9 brakes. The J55 brakes are on the Z51 and later model year F55 option C6. The J56 brakes are the option on both the Z06 and Grand Sport models.J57 is the carbon ceramic brake package on the ZR1 and Z07 Z06 models.

• JL9 - Front 325mm/12.8"; Rear 305mm/12" (base model)
• J55 - Front 340mm/13.4"; Rear 330mm/13" (Z51 model)
• J56 - Front 355mm/14"; Rear 340mm/13.4" (Z06 and GS)
• J57 - Front 394mm/15.5"; Rear 380mm/15" (ZR1 and Z06/Z07)

Apparently the front calipers are exactly the same for both the JL9 and J55. The rear calipers of the J55/Z51 have slightly smaller pistons than a rear JL9 caliper in order to maintain the correct front/rear hydraulic bias with the larger rotors of the Z51. Most likely we will convert our base JL9 brakes to the larger Z51 brakes, which is very cost effective.



All model C6 Corvettes have factory front and rear brake ducting, and I will show more of this in future updates. Amy's JL9 rear brakes (above left) are incredibly small and instead of spending hundreds of dollars on track brake pads for these we will upgrade the rotors and calipers to the similar but larger J55 from the Z51. I will show costs for each mod done to this car and the J55 brake upgrade and refresh will be one of the most affordable upgrades. Going to the J56 brakes (above right) would cost more than 5x as much.

RELIABILITY MODS

We want to be able to drive this car to local events. Nothing sucks worse than driving to the track and having something break, with no truck/trailer to bring you home. To proactively prevent some of this drama we will do a number of upgrades to make this car ultra reliable and bulletproof. Two of the things that come to mind are cooling and oil control. With the higher temps we see in Texas and the higher grip we will see with "tires that start with a 3" we are pushing the stock cooling and oil pan beyond their capabilities.

The factory C6 radiator is a tiny little thing with plastic end tanks, and at 16 years old things are probably starting to get brittle. I know we will tax the limits of the stock cooling system in the Texas summer months, even with a bone stock 6.0L LS2 engine. We will replace the radiator soon with something like this massive DeWitt Pro Series aluminum radiator (below left). They make drop-in replacements that massively improve cooling capacity and efficiency. That is the unit Koenig's C5 has now and it is ROCK SOLID reliable. We recently ran his car at an "autocross" that was actually held on a road course, and with two drivers making 10+ runs back to back, never shutting off for nearly 90 minutes... it sat at 205°F all day (the thermostat opening).



The other big thing we HAVE to do soon is an Improved Racing oil pan baffle / crank scraper, shown above. Any LS engine has pretty poor oil drain back onto the spinning crank, which turns the oil to foam and burns it under hard use. High G lateral and braking can also slosh oil away from the pump's pickup.

This car has a "wet sump" LS2 engine - but these can and do last on track IF you keep the oil pick-up submerged in liquid oil at all times (a dry sump isn't "required" for track use, like some people like to insist). A better oil pan baffle is usually all you need, and of course, keeping an eye on the oil level after every track session. The oil pan gasket seems to be leaking on this car right now, so dropping the pan to fix that was already on the list. Adding the baffle isn't much more work when you have the oil pan off.



We also want to keep an eye on the oil temps. Going to an external oil cooler (like this Derale 10000 series below left, on a customer's endurance CTS-V) would give me a good excuse to replace the "thimble sized" oil filter that all LS engines are stuck with (above right). If we do an oil cooler we will also add an external oil filter with a thermostatic bypass (below right, Improved Racing unit we like to put on lots of cars). That let's us move to a MUCH larger and more effective oil filter.



We won't jump off into that set of modifications unless the oil temps noted during track driving push us over safe levels (275-300°F max temp is about the limit I go by for reliable oil system use).

WHAT'S NEXT?

I have started cleaning things and ordering parts, and of course our new fashion needs. That is enough for an intro post.



We will setup a time at a local shop to get a baseline wheel dyno test, then at MSR-C to get the baseline laps in on these stock 245/275 all seasons. Then we will write another post after the video and dyno charts plus the initial suspension bits, wheels and tires, and other changes in store.

Thanks for reading,

[Fair!]

Project Update for May 4, 2021: It has been about a month since this project began and we have already completed the first two track tests and done one round of mods, with a load of parts ordered for rounds 2 and 3 to follow.



The C6 was pretty slow on track in bone stock form, and we weren't back at the shop five minutes from that event before we ordered the brake pads and three sets of wheels! One set of wheels was a mistake, but all of these sets do now have a purpose. Let's dive into the work we've done in the past 4 weeks.

REPAIR & MAINTENANCE WORK

Any 16 year old car - even one with low miles like this one - is going to need to need some maintenance over the years. The last owner deferred a few things, which is fine - we inspected the car thoroughly at the shop before we bought it, and knew all of that. It wasn't much and we chased down a few parts to get this C6 whipped back into shape.

FIX THE SQUEAK + ENGINE BAY DETAIL



There was a squeaking pulley bearing under the hood, so we bought what we thought was the likely culprit - the main serpentine belt tensioner. The hood struts were blown so those were ordered and quickly installed. I also ordered some new NGK spark plugs, Taylor 409 series plug wires, and an oil pan gasket - but we haven't installed these last 3 bits yet. You might see my new jean shorts (jorts) in the pile of parts (above right) - its called fashion!



Brad replaced the tensioner replacement and hood struts, then I detailed the engine bay after hours. It was just dirty, nothing too nasty in there, and soap and water plus some brushes and water got it all clean - then I got it all shined up with my underhood detail tricks. I have left the LS2 "coil covers" on the engine for now, just to show how stock it still is. The coolant reservoir is a little dingy so I ordered one of those new, which we will install with the full round of radiator upgrades.

OIL & FILTER + BRAKE FLUID FLUSH

Driving on track with a purpose means you are pushing the engine beyond the loads seen in a normal daily commute. And this base model has no oil cooler, which might prove to be an issue long term. As such, we didn't skimp on the new oil - Motul 5W50 Ester based synthetic does the trick.



This particular mix from Motul only comes in this weight, but for the hot and cold weather we see in Texas it works well - and I have used this exact oil on multiple cars and engine platforms. As for the filter, the Wix XP will do just fine.



This base model C6 doesn't even have much of a power steering cooler - just the "loop cooler" shown above - so we will wrap the power steering cap with a rag and zip tie to catch any fluid that might get by the cap when it first goes on track. We do this on all hydraulic power steering systems, especially on GM cars (which tend to suffer from fluid spillover at track speeds). Turns out that was a good idea, as this was the one fluid that did spew out at both track events (see top right pic) - that was a freshly detailed engine bay so all of the "shiny sports" were power steering fluid. We will flush and add synthetic fluids here and might be adding a real power steering cooler as well.



The brakes... this was a dilemma. Do we preemptively change to proper track pads or complete the first track test on these "street" pads? Jason said he had installed "the cheapest parts store pads" recently, and they were at full pad depth when we checked. I wanted to get the car on track ASAP for the baseline stock laps, so we left the stock rotors and pads in place and Brad just flushed the (black!) brake fluid for Motul RBF600 (these pads were horrible - this was a mistake).

REMOVE FRONT LICENSE PLATE

This is not something meaningful to maintenance or performance, just a styling thing that is is a personal pet peeve of mine. Removing the front license plate is a technical violation of state law here. But this is just a "paperwork violation", and no harm comes to any human being in any way by not running a front plate. Only 31 of the 50 US states require this, so it is not even a consistent law across this country. When I get pulled over for this I will tell the cop I identify as a Louisiana resident! (where it is not required).



After removing the front plate I assumed there would be two ugly holes in the painted front bumper cover, like there is on most cars fitted with a factory front license plate bracket...



I was glad to be wrong! There is just some "sticky goo" that was holding the vertical portion in place, and even after 16 years of use it was able to be removed and there wasn't a single scratch on the paint! Way to go GM - one pleasant surprise about this factory front plate bracket. I am an outlaw now, woo! Stay tuned for my 31 state crime spree and impending jail time.

SEAT TESTING & INTERIOR DETAIL

At first glance you might look at this car and think, "Sure, those look like sporty, supportive seats." Let me assure you, they are not. This is one of the least supportive seats in any modern sports car I've ever driven on track. The C7 had optional Competition seats that are crazy good, as does the C8, but the C6 generation on back had pretty much "good enough for grandpa" grand touring seats that should be replaced on any seriously tracked Corvette.



That was the biggest difference when I drove these two cars below - the C6 Z06 had the slightly more sporty versions of the base C6 seats above, whereas the C7 Grand Sport had the amazing, optional C7 Competition seats.



With both cars on the exact same tires (285/335 Michelin PSS), both driven the same day, and by the same driver (me) - the C7 GS was a full second quicker. And honestly, part of that was the seats.



It was MUCH easier to drive hard around corners in the optional Competition Sport Seats in the C7 GS. Those seats held me in so much better compared to the C6Z seats, which felt like I was gonna fly outta the damn window. REALLY have to exert a lot of upper body strength and concentration into "holding your body in place" in sub-par seats. The C6 has no such option like the C7 and C8 models do.



If you have followed any of my Forum Build Threads over the last 20 years, one of my common themes is - I always put fixed back racing seats (and usually at least a 4-point roll bar and harnesses) in every car that I track and/or autocross seriously. Even budget builds, like our GRM $2010 Challenge winning E30 (above right). Part of this is the safety aspect, sure, but mostly it is done as a driver comfort and control upgrade. Having done seat installs for 100+ customers over the last 16 years at Vorshlag, the universal response after the first time they get used on track is, "Wow! I wish I would have done this seat upgrade sooner!" It is a huge change, and is worth actual lap time. Not to mention a way to fend off back & muscle ache after a long session on track.



Here are two different stock C6 seats we weighed. The power driver's seat from our 2006 is remarkably light at 45.6 pounds (we have weighed many in the 70-80 pound range). It also has power fore-aft and height adjustment, not to mention the tilting backs like all OEM seats. We then weighed a manual adjust seat from the passenger side of my 2007 C6 Z06 (that chassis is in storage) at 40.1 pounds. Also very light, and you can barely see the deeper side bolsters on these seats - which is still not NEARLY enough support. Plus these have no shoulder harness pass-thrus or a anti-sub strap pass-thru, for use with 5/6/7 point harnesses.



We had Koenig's C5 in the shop altering his Sparco EVO II US seat placement with our prototype C5/C6 seat bracket bases, so we pulled the driver's side out, weighed it and put it into the C6. At 41.0 pounds (with our seat base, side brackets, lap and anti-sub belts, and Sparco EVO II US seat) it would work, but the "step-over" of the lower leg bolsters on these seats is pretty high, and of course there is no seat back tilt function. It was still a bit tall for me at the layback angle for the seat we needed for Koenig to fit his C5 well, and this limitation would definitely affect the seating position needed between Amy's (5'6") driving position and mine (6'3") in the C6. Fixed back seats are also a pain to use every day in a real street car, and often make it hard (or impossible) to use the OEM 3-point retracting seat belts, depending on the seat's lower design aspects.



After having driven stock C6 seats on track I knew how bad they were, so before we even took the car on track we started to look at some better Tilt Back seats, including several aftermarket versions we had on hand. The first one tested was this Sparco R333 "tuner" tilt back seat, above right. This one fits Amy's torso length well but not mine - it puts the shoulder pass-thrus several inches below the tops of my shoulders, which would compress my spine in a crash with real 6-point shoulder harnesses. That seat choice was right out.



Next we tried this Corbeau RBR tilt back seat we used to keep in our lobby. We have an older (2015) version of this seat on hand but the basic dimensions haven't changed. The side bolsters for the base (legs) and back (torso) are MUCH deeper than any OEM C6 seat. This is a steel framed / bottom mount seat (like OEMs) that comes in around 25.6 pounds. We put this old, dusty seat in the C6 to test how it fit me and Amy both.



Having driven with this RBR seat on track I know it works well for that use, even with just a 3-point belt - but it works even better with real harnesses. This one fit in the C6 very well, and as you can see (above right) the shoulder harness slots are above my shoulders, so it will work safely for taller torso heights. Amy noted that they are a little harder to get into/out of with the deep bolsters on the base. But they ARE setup for 5/6/7 point harnesses so it us still a solid choice for a dual purpose street/track car. The one down side - you cannot lean the seat forward past vertical, due to the side bolsters from the seat back and base running into each other - so if you need to get into a back seat, you really can't with these seats.



After she asked for another seat option I looked up and found this newer Corbeau RRS seat, shown above. This is essentially the same seat as the RBR on the torso section (the updated should harness pass-thrus look remarkably like the C7 sport seats now, and the current RBR has the same update) but with a more OEM like lower base section. The lower won't hold your legs in as well on its own, but will still allow a 5/6/7 point racing harness to be used, which can really holds your body in place when driving on track. It was a compromise seat that will be more friendly to street use (easier ingress/egress), so after Amy picked the material / style she liked and added the optional seat heater on the driver's seat, we ordered the pair. When you are old and/or have back problems, these seat heaters are a real life saver, trust me!



Whenever we have seats out of any street car we vacuum the carpets, and this was a good time to shampoo them as well. Tons of stuff was found underneath both, and the passenger side carpet had coffee spills that turned the hot water in our carpet shampooin'g vacuum brown. After a few passes with the hot water spray and vacuum, the carpets were clean and it smells like new inside now. We left the car open with a fan blowing on it all night to dry and then Brad put the stock seats back in. The Corbeau RRS seats shown above had a 4-5 week lead time (they just shipped, so almost exactly on time). Will show that install next time, along with a new seat base we will make for these bottom mount seats.

FANCY FLOOR MATS

This was a barely needed maintenance / interior upgrade, and might seem a silly thing to even list in this "build". It was just that the $9 parts store floor mats that came in this car were SAD. I found these "officially licensed by GM" mats online for a decent price and took a gamble...



These Lloyd's Mats are actually very well made, and these were a perfect fit for our C6. I've since found out you can custom order from their website in a number of different colors, 4 carpet thicknesses, with tons of options and embroidery patterns to choose from.



The black of these mats matches better than the pictures above would seem - it was a photo exposure thing - but I'm very happy with the result. Of course we remove the driver's side floor mat before it is driven on track, even with the OEM "hook mounts" engaged. Don't need a mat slipping under a gas pedal or something like that on track.

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TRACK TEST #1 APRIL 9, 2021 - STOCK BASELINE

With the initial maintenance items handled, some proper oil and brake fluid in the car, and with the C6 in otherwise sad stock form it was time to go to the track to get our Stock Baseline Laps in. This is the target lap we will try to improve on with this build. We utilized Motorsport Ranch in Cresson TX for this round of testing on a member day when they ran the 1.7 mile course in the CCW direction.

Event Gallery: https://vorshlag.smugmug.com/Racing-...mys-C6-040921/

I was hoping to get some laps in at ECR on the same stock configuration but our membership there might be delayed a bit. So we will use the MSR 1.7CCW to do all of our testing, for now. As I explain below in more detail I have over 500 laps on this layout over the past 2 decades and it works well as a test track, due to the layout, length, consistent surface condition, and my familiarity with this course.



Amy and I left for the track around 6:30 am and got there just after 8, with fairly light traffic for a Friday morning. We quickly unloaded the C6 then... realized we had outdated schedule info on when the first cars would go out on track. So we took the time waiting for the track to open to get two cameras installed, the AiM lap timer, then checking fluids and tire pressures. We went out with 31F/30R psi cold pressures - which turned out to be WAY too high.



We were there the same time as a lot of track friends with much cooler cars. I only barely remember seeing any of these cars out there when we were, as we had our hands full trying to keep this C6 on track while fighting brake fade and of course the REALLY poor stock seats (which were worse than I remembered).



We went out a bit early in the "8:30 am" sports car session and spent 34 minutes straight driving this car, swapping drivers on pit lane. We had some real concerns - with the brake pads overheating and the oil temps touched 275°F - but we were really watching oil pressure. The digital gauges on the C6 can only show one thing at a time, and while Amy was driving I was looking at that number closely under braking and in corners (by the next test I had enabled the CAN data to log this). I never saw oil pressure dip under 40 psi.



Click the image above to see the best lap on YouTube. Amy happened to be riding along on that, and I explain why below. Made for some hilarious in-car commentary! She was not having fun riding with me, but she took 6 hot laps when she drove (she is never a good "passenger" on track!) Our AiM DL was only setup to get the basic OBDII data - tachometer, Throttle Position Sensor, and a few other useless things (I had CAN data logging enabled for Track Test #2) plus the g-meter and GPS from onboard the AiM.



I went out alone for the first stint and the stock brake pads were VERY unhappy, and the 245/275mm all seasons were howling around every corner. I could overheat the brake pads pretty easily, so I had to baby them to get them to cool back down. So I adjusted my driving to not use as much braking - definitely an area we can improve upon for test #2. In my first stint I ran two 1:29.93 laps followed by a 1:29.67, a bit frustrating and very very slow. Amy ran 6 hard laps with me coaching and was finding time - but the brakes were not giving her any confidence. Then we hot swapped for 2 more hot laps with me driving and Amy riding right seat. Bleeding tire pressures down allowed me to drop a solid second from my first stint to a dismal 1:28.743 best lap.



We tested a new video camera along with the trusty Sony HDR-MV1, and the RoadKeeper dual 1080P vidcam was a roaring success. I will cover more of this in a review next time, but after 2 track events using it I am very happy with the video quality and the dual cameras is a nice feature. There are some quirks and cons, of course, but I will go over those in the review in my next Forum Build Thread Update.

I was only watching the oil pressure gauge while on track, as scrolling through two screens to see TPMS data is impossible. We stopped to check then bleed down the tire pressures after my first stint. Amy said the fronts and rears were at 45 psi after I came in! I had her bleed those down to 34F/33R psi for her stint, and we bled them down again at the next driver change - when I drove and she rode shotgun with me. Having tire pressures in the right range made a noticeable difference in grip, allowing me to drop nearly a full second in my last stint, even carrying a passenger.



Those lap times are painfully slow (you can see how they ranked in my "lap list" at the bottom of this post). Sure, both of our driving was pretty rusty, but I felt the rust "breaking loose" on my second stint. My last time on track was here in January of 2020. Amy's last time on track here was in 2018, and she never got into a good groove - when she's comfortable in the same car she's usually in the same second as me (and has NASA TT wins of her own). I tried to get her to go out again in a later session, but there was going to be an hour of waiting (open wheel cars and motorcycles each had 30 min sessions) and she was ready to go. The ineffective brake pads were just not confidence inspiring AT ALL, and I don't blame her. I sure didn't want to drive it like this any more!



The stopping performance on the random parts store pads was just BAD - two half-serious stops in a row would overheat them. As we swapped drivers in the pits there was smoke POURING off the front brakes (from the lack of airflow while stopped - they heat up). Next lap out the pedal would go to the floor on the first stop, so we had to make cool down laps at both the end and beginning of each stint.

REPAIRS AND UPGRADES - ROUND #1 MODS

Looking at the front tires after this event, I am surprised they weren't just shredded on the shoulders, as much as these things were howling and understeering badly. Turns out when you have rock hard 500 treadwear tires, they don't wear super fast. They also didn't make much grip!



This car had a mix Goodyear, Hankook and Michelin tires when we bought it, with that 30mm spread in front to rear widths (245/275) - which contributed to the serious understeer the car had (per the GM design - to make it safely understeer for the "lowest common denominator" random Corvette buyers). We needed something better - and now.

INTERIM WHEEL & TIRE UPGRADE

On previous projects where we have chronicled lap times with major mod levels along the way, we upgraded the tires and sometimes even the wheels right after the baseline stock laps. Sometimes we would add an an "interim" set of wheels and tires that are better than the stock rubber, but not quite the competition set we would end up with. Tires is the biggest early upgrade we can do to any project - as nothing is more important than tires to lap time performance. With the staggered wheel widths it was necessary to upgrade both wheel widths and tire widths. We had an "extreme fitment" set of 3-piece wheels already on order but I needed something to arrive in the next few days, as we wanted to get back out there and improve on the dismal baseline lap time ASAP!



Unfortunately we didn't have a significant amount of experience creating wheel fitments for the narrow body C6 (we have lots of wheel experience and sales on the C4, C5, widebody C6, and C7). With a 5-6 week wait on our "real" wheels I just wanted to get something "square" - the same widths front and back - and quickly. TireRack is notoriously hard to look for non-stock wheel sizes, but we found two options that looked like they might fit - shown above. The 18x11" OZ was a bit pricey and was a "rear only" C6 fitment that might poke on the front. Instead of taking the chance on a $1400 set of 18x11s that might not fit I went went for the Flow One F4 wheel in 19x10" - also a rear only fitment - for $400 total. I ordered these minutes after returning to the shop after Track Test #1!



Tire choice was a bit tricky as the "pandemic surge" of parts orders and shipment issues have made for a serious shortage of tire options. This reduced our choices in tires to fit these 19x10" wheels, greatly. Luckily the 275/35R19 size is not super popular in the 200 treadwear tire wars that track folks are fighting, and we got this long lasting Hankook RS-4 in that size - which I have driven on before and really liked. This compound is popular for endurance series events, as it is and not as soft (nor as fast) as the "one lap wonder" 200TW tires - A052, RE-71R, RT-660, Rival S 1.5 and the like.

The RS-4 wears VERY well on track and this tire should allow us to still get fast laps deep into a session, without having to nurse the tires and shoot for a fast lap quickly before they overheat (like the softer 200TW options - which I treat like a Hoosier A7). There was some concern that the staggered OEM tire heights front to rear might be an issue (the old front tire and new one side by side show this), but it turned out not to be the case.



There's always a fine line between light wheels and strength, but this flow formed 19x10" wheels weighed about what we expected them to - 21.8 pounds (pretty close to the 21.6 TireRack claims). Sure, an 18" wheel would be lighter and more than tall enough for the base JL9 brakes or just about ANY brakes we might use on this car. But wheel COST and quick AVAILABILITY were key here. These 19x10" wheels were on closeout at $124 retail (minus our shop discount), so it was a very cheap upgrade.



Surprisingly the stock rear 19x10" wheel and 275 tire was only 1.2 pounds heavier - we normally see a bigger drop over OEM wheels than this when going to aftermarket flow formed wheels. We had TireRack mount and balance the set, but they didn't have the TPMS sensors in stock, so we just had them use normal tire valves. We wanted this set here in a few days, and they made it happen - with one small mistake.



The math from our previous wheel measuring session (covered in my last post) showed this 19x10" would fit within the envelope Jason had designed on the front, but we still held our breath as they went on. They cleared at full steering lock in both directions and had #NoPoke at both ends. Surprisingly the stock rubber front control arm bushings are so sloppy that when backing up (reverse) at full lock the tires DO rub, ever so slightly. We will address those bushings and their gross deflection in a future round of mods.

TRACK PAD UPGRADE

So this is going on a bit of a tangent, but for a purpose. If you have ever ridden with me in an autocross or on track, one thing might jump out at you - I push the tires hard, trying to keep them loaded on the edge of their Friction Circle at all times. As such I tend to brake LATE and HARD, then get the turning phase of the turn going, and start adding throttle as soon as possible (at or before the corner's apex). I never EVER coast - I'm on the gas or brakes at some point at all times, and I always Left Foot Brake if there is no downshift needed for a corner. To me, coasting is the greatest sin when driving on track. When I am right seat coaching someone trying to find lap time, this is where we tend to find the biggest gains - by reducing any time spent coasting. This might not be how you drive, but it is how I do it, and it has worked for me.



I also transition from gas to brake after a straightaway very quickly (sometimes even abruptly) when entering a corner, then transition to trail braking, then get off the brakes as soon as possible and start feeding throttle. To some, that means I "abuse the brakes". And yes, to those that like to tip-toe and gently squeeze pedals, it seems abrupt - but my driving style (and the way I was taught) was to always keep the tire loaded. "Smooth is Fast" might be your motto, but "Coasting Is Death" is mine. When driving the same car with others and comparing data, I often extract more braking g forces, and sometimes touch the ABS limit on many cars. Nobody can say I am coasting or under-utilizing the brakes.

Could I drive faster? Sure, I'm not naive - there's always someone that can eek out more time. But after three decades of Time Trial competition, with thousands of laps data logged and analyzed, I've found that pushing the braking as late as possible is some worth lap time, for me, rather than just lifting / coasting or "easing into" the brakes. A good ABS system can cover up any abruptness on the middle pedal, and the tenths gained in braking zones can add up. I have passed a lot of lighter cars under braking after high speed straights, like into T1 or T12 at COTA.



This long tangent was written because - some people don't "understand" the brake system problems that we have uncovered when I push a car 10/10ths on track. Comments like "These Hawk HP+ brake pads work fine for me!" online are always followed by my question of "yea.... but what are your lap times?" Because driving slowly won't tax the brake system like driving faster will. My point in all of these back-and-forth comments is that NOT EVERYONE USES THE FULL CAPACITY OF THE BRAKES ON THEIR CAR when driving on track. So my driving style tends to use all of the brakes, and can quickly find weaknesses.



We looked at the C6's brakes before Track Test #1 and they looked fine. Rando parts store pads but at full depth, and the PFC twin piston front calipers looked fine, just needed a flush. After 12 hot laps at MSR in Test #1 (which is a track not known to be hard on brakes) the pads were shot and the front caliper's dust boots had caught fire and mostly burned away (hence the smoke). This isn't alarming or unexpected - I've used to PFC calipers on cars going back to the 1990s, and these dust seals are not what seals the pistons from the fluid. Real race calipers don't even have dust seals.



While the stopping power of the parts store pads was hilariously bad (as expected), we had planned on getting proper G-LOC track pads after the first test event. I wanted to drive the car first on the stock pads to see what race compounds we needed. Danny at G-LOC rushed built and shipped us a set of R12 fronts and R10 rears. As you can see above, the previously new front pads were 2/3rds worn out in just 12 hot laps. I was pressing the pedal will all of my strength on some stops - but they just don't have the friction capability when hot like real track pads do.



We staggered the pads one step in compound front to rear - using a harder R12 up front to the slightly less aggressive R10 on the rears. This is a normal technique we do for all manner of cars, based on how weight transfer naturally forces more braking abuse to front brakes versus rears. Now I normally run even more aggressive R16 front and R12 rears (which is also one step front-to-back) on most cars, but I was worried that the more aggressive R16 might be too much for the notoriously finicky Antilock Brake System programming we have noted on dozens of other GM cars. Turns out even these milder pad selections were still too much for that GM ABS...

TRACK TEST #2 APRIL 18, 2021

This was our first track test after our first real "performance modifications" to this base model C6 - the stickier tires on wider wheels plus the track worthy brake pads. We had wanted to get a performance alignment before this test but the timing didn't work out. This time Amy and I went out on a Sunday, which was also a member day at MSR on the 1.7 CCW course. The weather was perfect and we had a lot of fun that day getting our laps in.

Event Gallery: https://vorshlag.smugmug.com/Racing-...Test-2-041821/

We towed the car in the trailer again - we almost drove it out, but we managed to load the car in under 15 minutes and the truck & trailer is good peace of mind. I drag a lot of tools and electronics out to these events and didn't want to leave something behind by driving the car out. Turns out I left the Canon DSLR camera, so we got no "on track" pics other than cell phone shots.

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