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Unread 03-25-2016, 08:39 AM
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Fair! Fair! is offline
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Join Date: Jul 2004
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Default Re: Vorshlag Budget TT Build: Project DANGER ZONE

Continued from above

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



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



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



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


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

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


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

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



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



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

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



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

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


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

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


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

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

POST MSR-H DECISIONS & CHANGES

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

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



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

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



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



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

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



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

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


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

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

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



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



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



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



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

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

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



continued below

Last edited by Fair!; 03-25-2016 at 08:55 AM.
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