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Unread 05-20-2015, 10:00 AM
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Join Date: Jul 2004
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Default Re: Vorshlag Build Thread - Mark C's 2002 C5 Corvette Track Rat

Continued from above



This C5 did have some good parts on it when Mark bought it (harness bar, seats, harnesses, headers) and the one thing we added helped (18x11's and bigger tires), but it was still full of what I call "eBay parts", the lowest cost options sold by shops that don't have hands-on experience.

My perspective is that there is a lot of "group think" that comes from internet forums, some of which is led led by shops and parts sellers, but most of it by like minded folks. Because of a strange set of circumstances the worst parts available (the cheapest) end up being the ones most people buy. Why? Because people are convinced they need a lot of parts (many that don't really help) and they want the best deals. So a lot of folks end up buying the cheap option that everyone else recommends. They then shout about the new parts' positive qualities while ignoring the obvious problems, to help justify their purchase. This process is how low end parts are often touted as the best parts, without the buyer realizing the compromises inherent in them. "Most Popular" doesn't equal "Best". We see it in every market, and the Corvette world is no different. Sure, some folks know about proper dampers and choosing quality parts, but the racers at the front of the pack don't usually share their setup secrets as freely as the Internet Forum Experts. /EndOfRant



In the end, all of the issues I noted in this car were created by a few upgrades that just didn't work well together or with the rest of the car. Some of these parts may work in some special circumstances, or with specific other parts. The Konis that were too long might work fine at bone stock ride heights; the cam that is too big and wrecks the power curve would probably work great in a bigger motor with more rev potential; something goofy happened in the tune but it could have been from a part installed after the previous shop programmed the ECU; a grabby twin disc clutch that made it impossible to launch smoothly is often needed at power levels much higher than this car has; and the loud flashy quad-tipped exhaust makes the car miserable to drive. The mis-matched brake pads that made the rear tires lock up were just a bad decision on my part - I should have insisted on a new set of pads be used at both ends, in a compound/brand that we trust, instead of using random stuff that came with the car. Honestly, a bone stock 2002 Corvette would have been faster than this combination of parts, and a damn sight easier to drive.



The Saturday events also included the Design and Engineering challenge, which tends to have real "hit-or-miss" scoring on the judging. The 3 judges can spend anywhere from 2 minutes to half an hour on any given car. They are supposed to check off items from a list for "streetability", which accounts for 15 of the 25 points. Glass, interior/carpet, HVAC/interior electronics, exterior lighting and "ergonomics". Then they look at unique engineering and modifications, fabrication work and "car show stuff" for the remaining 10 points. I saw one entrant who had a power point presentation on his laptop hog 25 minutes of the judges time; others would rattle on and on about stereos, fake roll cages, and all sorts of non-performance stuff I don't care about. Like my general disdain for car shows, this is my least favorite element of Optima, but its a necessary evil and it is't ever going away for this series.



It is also where they are supposed to weed out the "dedicated race cars" with no interiors, but that doesn't always happen, either. So we had washed Mark's Corvette before this event, but after nearly a day of driving it was dirty so I cleaned up the exterior and interior quickly while waiting in the very long line. I ended up cleaning a few of our other cars in line as well.



At least we spent some time actually trying to apply the many Optima series + sponsor decals on Saturday morning, and we washed our cars (some did neither), so I guess that helped our scores. The C5 ended up in 5th out of 16 in GTS class, behind only two dedicated race cars, so I guess washing the car helped. Amy's Mustang got 2nd in this category in GT class and our customer James Meeker (supercharged Roush Mustang) got 3rd. Both of those cars have all the street gear and LOTS of mods we've done, so I was pleased with that outcome. But since this is the only competition event that isn't scored by your "ranked" placings, the last placed car in GT class (a gutted race car) still had 17.4 points, whereas the first placed GT car had 20.3 points.

Moral of the story is don't be afraid to BRING A RACE CAR. This is not meant as a critique of how USCA scores this sub-event, just a warning to potential competitors to help them focus on what matters and ignore what does not. The three driving competitions are scored differently - your actual best lap time gives you a ranking in class, and your rank determines the score (1st = 25, 2nd = 22, 3rd = 20 points, and so on). It becomes obvious that placing well in these 3 driving events in your class is CRUCIAL to winning the overall with all 5 events' scores tallied up.



The Speed Stop was the other event on Saturday, and my experience in 4 former Optima events probably helped bolster my times, but it still didn't keep me from getting beat by even some Novice AWD drivers in GTS class. This is THE event where AWD really shines, and the top 5 times of this class were EVOs, GTRs and STis.



Amy got a decent time for GT class but as you can see below, I ended up way down in 7th place for Speed Stop with my 10.584 second time on my 9th and final attempt. Same issues in the autocross fought me here on the C5: grabby clutch made launches difficult and the mismatched pads made for ICE mode stops, so I had to brake at about 8/10ths to avoid rear lock-up and axle tramp.



After the 6+ hours of driving in the Autocross and Speed Stop events, plus the other hours spent prepping, walking course, or getting judged on Saturday, we were all exhausted. I was pretty disgusted with my driving and the handling in the C5, and was dreading having to drive it 70+ miles around town on the "Road Rally". This is where cars have to prove their worth by following a path on city streets, usually in traffic and on secondary roads with lots of bumps. This C5 was driving me nuts and wouldn't idle, wouldn't start smoothly from a red light, and the exhaust note was maddening.

I ended up leading 6 other cars from our group at the track to the Rally party, so we only went to the marked checkpoints (beginning and end) on the map and cut out the crazy route they had chosen. Why? Because as we have found out in multiple Optima events in the past, it doesn't matter - they don't have hidden checkpoints and half the field skips the route and just goes to the end. I have complained about this loophole before, but with over half the competitors short cutting the rally and nobody else seeming to care, I quit worrying about it and finally just took toll roads and nice highways all the way to the final checkpoint, at the Pole Position indoor karting facility.



Our entire group was hungry when we arrived, with most of us skipping lunch due to the long lines in grid and at all three Saturday events. The more competition runs we chose to take meant we could place better, and Amy and I both got some of our best runs at the very end of the day (and in the Speed Stop we both nailed it on our FINAL run). Stopping for lunch was a luxury we couldn't afford. So by the time we made it to the Karting center we were pretty hungry, but it was going to be an hour and forty five minutes before they served dinner, so many folks just checked in for the rally and then left.



Too bad for them! Several of us burned time buying a "3 race package" that turned into 6 races and we ran the karts all night. The food was Bar-B-Q from Rudy's that was EPIC. With about half the 100 people not there we all got TONS of food, going back for seconds and thirds. The racing action was pretty fun but somebody kept putting me, Jon, and Aaron from DuSold Designs back on the "next up" display, and we kept taking laps. Lots of fun, but I was thoroughly exhausted by day's end after 5 or 6 sessions of karting - on a full stomach, after an exhaustively hot day. It was shorter distance to just drive all the cars home than take them back to TMS and leave them in the NASCAR garages overnight, so we headed for the house. It was 9:30 before we got back home, and Amy and I immediately crashed out while Matteucci was soon snoring in our guest room.



Speaking of Aaron, he did DAMNED well in his 2015 Mustang PP, which we've used as our test bed for S550 suspension development. The first MCS coilovers, the first Vorshlag camber plates and the first Forgestar CF5 18x11s were fitted and tested on this car, and the results were pretty amazing. This car goes, stops, turns, and rides better than a similarly equipped S197. I'm not kidding - its pretty amazing, and if you didn't know it was a Mustang on the outside, it might fool you into thinking it was a BMW by driving it. Ford nailed it on this one and we got it right on the spring and damping for the suspension.



Aaron drove well and with this car's bone stock brakes/pads/fluid, stock power (it has an axle-back exhaust), and the other performance mods we've helped develop he placed 3rd overall in GT class, behind the 3 race cars. Initially he was ranked as 4th, but a mistake in calculations put him ahead of one of Ken Thwaits's two Camaro entries in the final tally. Aaron scored 4th in Speed Stop, 7th in Autocross, and 5th in the Hot Lap portion. Dusold Designs has done other mods to this car including a custom grill, tow hook, rear spoiler, custom splitter (not in place for Optima) and other updates.



So Sunday was the Time Trial portion, and I explained Amy's issues above. She just didn't have confidence in the set-up, with the change to street tires and no aero making the car very different. She put it in the trailer after her big spin. Matteucci took all of 6 laps in one session and the exhaust smoke screen got so bad that he ended the day early. I am stubborn and kept trying to battle my way to a better time with the C5, but only took 14 laps in two track sessions before calling it a day. I've never found a car I couldn't "drive around the problems" in, until the eBay Corvette.

The clutch was no longer an issue on the road course, unlike in the Speed Stop or Autocross, but the rest of the parts mismatch problems were amplified at the higher speed road course event. The TMS infield isn't a traditional road course and the short course length surprises many with the higher speed corners and treacherous off course potential. There are tire barriers and concrete walls aplenty, but it is what it is - there is no other road course site in Texas that has the room to run the Autocross and Speed Stop simultaneously, this side of COTA ($$$).



We went out on track in the first session but Danny Popp's GTL classed C6 Z06 entry only made it about 50 feet before something in the transaxle exploded, and the Expert 2 run group got a black flag. He laid down a little oil but the track workers had it cleaned up in about 10 minutes and off we went. Popp also had a set of BFGoodrich Rival-S tires, along with Kyle Tucker, but since those tires wouldn't be available for normal folks for weeks or even months, these two cars were moved to Exhibition Class. That was the right call by USCA and I applaud them for following their rules about excluded tires.



Danny wasn't the only one who suffered mechanical issues, as the newly built tube framed 67 Camaro of our friends at Dusold Designs also had some teething troubles. Mike was FAST on the autocross course in this lightweight machine but when a control arm pick-up point failed, they had to run back to their shop in Lewisville to build a replacement. They weren't 100% confident in the fix, so after Mike drove the car on the Road Rally they called it a weekend. Didn't want to see this wild but mostly untested creation wadded up on the road course on Sunday.

My first track session in the C5 was full of traffic but uneventful, other than I was cursing at the car for being such a mess to drive. By session two the track temps were up in the right range, and I knew I needed to lay down a good time NOW. Unfortunately the car just would not stop, turn or corner worth a damn. The non-Z06 C5 gearing is weird, and every corner and straight was right between 3rd and 4th - so it was either making NO power in 4th or revving to the top of the range in 3rd. The brake pad mismatch made the rears lock constantly, sending the rear axle hopping and making it loose. The lack of bump travel in the rear made the rear loose over bumps and in heavily loaded corners. And the peaky cam made the motor come on hard and spin the rear tires.



The video above shows parts of 6 laps in Session 2, including my fastest on lap 3 - a 42.574 - while passing two cars off line. Traffic was brutal in the morning sessions but because of the spin I had at the start finish line after 6 laps during session 2, I called it a day. I'd already driven a borrowed car harder than I felt comfortable with and I wasn't going to wad it up in a concrete wall. I might have found some tenths in later sessions, but the 39 second laps I did last year in the Mustang were nowhere to be found in the eBay Corvette.

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