There is a point of no return with tire width. The drag is increased substantially. If the track, you are running is very tight or Autox the point will be higher. A good rule of thumb when developing or improving a vehicle's handling performance is to go +10 to 20mm in width and 1-2 steps up in tire performance. I would consider a 200tw 1 step up and slicks to be 3. Supercharger/turbo and a cage would be my next mod.

 

RE: ESC -- the difference between PTM Sport 1 (ESC on) vs Sport 2 and Race (ESC off) is pretty astounding; not sure how that translates to Competitive Mode, though. The ESC implementation initially feels pretty transparent until you drive with it off, then you recognize how much it's actually intervening from braking zone to apex to track out. With it on the car feels composed when trail braking, with it off it gets extremely tail happy. It eliminates nearly all exit oversteer as with it off I've found driving with the same (ostensibly poor ) technique I end up drifting around the carousel, etc.. It's great at what it's designed to do, but it can foster bad habits. The PTM modes in the C7Z are more progressive in terms of the leeway and slip angle it allows; C8 is more binary.

 

Alignment Specs (Camber, Caster, Toe; in degrees):

• Front: -3.5, 8.1, 0.00
• Rear: -2.8, 0, 0.05

Heights, weights with 192 lb ballast, full tank (FL, FR, RL, RR)

• 672, 668, 714, 713 (mm)
• 756, 725, 1160, 1127 (lb) --> 3768 lb total; 3576 lb curb without driver.
• LR + RF = 1885 lb; 50.09%.

Note: We had to remove even the small washers on UCAs to hit the numbers


Alignment sheet

 

Figuring out little details before the first track day:



I wish the OEM side skirts I bought were actually extending them; they're just covers. Anyway, a cover in there is not a bad thing since it'll take beating.


Decided to change phone mount again. This one covers a few of the HVAC controls when the phone is on it, but at least it's right by my eye sight and away from direct sunlight, which sometimes causes overheating of phones.




Installed a small metal plate behind the GPS transponder by its battery lid, and installed a magnetic strip behind the infotainment screen for easy mounting of the device in direct sight of sky. The metal plate didn't seem to hinder the performance of GPS signal, especially considering it's on the battery side, and not by where its internal antennas are.
EDIT: This did not work well; signal strength was not good.



Found a bicycle bar mount that worked perfect for my Insta360 camera. The original location I found, as seen in first pic, was not centered and was also tilted a bit. This one is so much cleaner and short (i.e. less flex and jitter).



I have winch the car in with its back first to hit the desired tongue weight for the trailer. A longer trailer would help, but then it would not fit into my garage : )
I don't need any boards to load up the car, but since steering is now at the back of the car being loaded, my steering corrections are delayed (causing an arc of direction change instead of a direct change), making it harder : (
I left the car in accessory mode in Neutral while loading up, which requires you to start the engine first (I think). This would be a challenge if you lose the engine, and need to tow the car at the track; they'd need a flatbed.


My camping bed is ready! With the HVAC and audio system running whole night with the hybrid system, it should stay very comfortable even though it's going to be hot out..

 

when and where is your first track day?

 

I'll be at Oregon Raceway Park, attending an 'open' track day, with no sessions. This should hopefully reduce pressure and let me do a gradual ramp up at pace.

Besides new platform, it'll also be the first time for me using the left foot for braking. I've also changed so many things at once as you see in this thread, and I'll need to 'listen' for anything that doesn't sound right.

The reservoir cables move up and down. I think I have enough room for their movement. The front brake lines were a bit more tricky. AP asks following stock layout, but it feels a bit short for that. I did follow, and it worked for driver side, but would bulge outwards and hit the wheel on passenger side. It might completely be my fault of course, but regardless, the seemingly symmetrical layout on both sides didn't work on one side. I worked on the layout until it worked in any steering angle. Here's hoping noone did any mistake on this, or they might slightly rub each time they're parking their car..

Another test will be coilover settings. Since I don't have a baseline, it'll take a while to start experimenting with different coilover settings.

I'm starting with Cicio's baseline:
Front Compression: 5 from full soft
Front Rebound: 7 from full soft
Rear Compression: 6 from full soft
Rear Rebound: 5 from full soft

MCS baseline is a bit different FYI:
Front Compression: 6 from full soft
Front Rebound: 8 from full soft
Rear Compression: 6 from full soft
Rear Rebound: 8 from full soft

Cicio mentioned 125PSI, and MCS mentioned 175PSI in instructions, and I don't have tooling to check or change the pressures by the way...

Another test is tires. I bet 295/345 will work with no issues, but wonder how 315 will perform. I think I should've mounted RRs on my other set with 315 fronts, not R7s, so I could test handlings difference as well; oh well.

So many things to learn and experiment on..

 

Great Info. Question about the alignment. Did you achieve these specs with the thinner washers between the body and upper control arms? Or did you have to go to no washers at all?
Also how does just removing the washes effect toe? Can the washers be installed and removed without impacting the other alignment parameters (other than Camber of course)?

Thx

J

 

Thanks for the question, I'll edit the post and add that "we had to remove even the small washers to hit the numbers".

My ride height is ~15mm below stock, and higher than some others' setup. If lower, it'd probably hit higher targets, too. I always like staying close to OEM heights, since the car's cooling, wheel clearances etc. are all designed for it.

 

Good to know... No washers for your (Track Spec) Alignment.

I still wonder can you add and remove the washers without impacting the other alignment parameters (other than Camber)?
And another question. Can you reduce the ride height 15 mm as you did without impacting the alignment parameters? If not which are effected?

thx

Jay

 

If you remove the washers it changes the toe.

 

Everything changes alignment parameters, really. When someone sits in the passenger seat - camber and toe change. What is an acceptable change in alignment after changing something relevant? That is pretty user specific. Some people need alignment specs perfectly dialed in always, and some people can be a bit more lax.

 

I've finally done my shake-down event. In short, it was a bit too hot for me and 'apparently' also for the car.

• The good
  • Reliability: Nothing I installed has failed; yay!
  • Transmission: Transmission was also excellent during the whole event, and shifted very crisp. I played with manual shifting, but the squarish steering wheel makes it harder for me. A friend suggested extended shifting petals; perhaps not a bad idea..
  • Behavior when stability fully off: I turned off all traction and stability control completely in last session to see how stable the car really is, and drove like that for 15 laps. It felt pretty stable. I slowly increased my pace back, and my optimal time even dropped to 1:51s, which is not too bad at 90 degrees F (but I didn't have a clean lap due to traffic). Using left foot braking might also have contributed to this, since I was ready to softly touch brakes whenever the car felt like it's coming close to limits.
  • Tire/wheel clearance: 295/345 18" RRs seem to have had zero rubbing or any issues! This is crazy for me, since even the widebody C7 runs into issues.. I also had a session with 315/30/18, 345/30/19 R7s, and they didn't seem to rub, either!!!!! I am yet to remove the tires to inspect everything, but from what I could see, so far, so good!
  • Left foot braking: This was easier at the track than at the street. That said, I'm sure I'm losing time since my left foot is still not as fine-tuned as my right foot. Alas, I'll continue to train my left foot : )
  • Brakes: They did well, and I didn't notice any behavior from brakes, which is a good sign.
• The bad
  • Bad camera angle: I should mount the camera a bit lower - will do next time.
  • GPS transponder location: It doesn't like being mounted next to strong magnets. I'll have to find a different spot for it..
  • The ambient temps: It was just too hot to do fast laps. I was getting used to the car in the morning when it was 70-80, and it was getting close to 90s degrees F when I picked up pace : )
    • I know that 90 degrees F is a normal temp for some who live in the south, etc. In PNW, we often enjoy events around 50 degrees F, at which pretty much every car works better (unless very light ones). As such, these hot days are not really ideal for us in this region.
  • The car was running too hot: I thought this car (C8) didn't have cooling issues??? It did not officially overheat, but its coolant temps hit far above the healthy range, costing quite a bit of power.
    • Even in the morning session at mid 70s (but full sunshine on the tarmac, getting it hot), I was able to quickly hit 234s degrees F on coolant, 217 degrees F transmission, and 244 degrees F oil.
    • As it came close to 90 degrees F ambient, I was hitting 237 degrees in about 2 laps, and would have to do another 2 laps of cool-down to get back to a healthy range. Another observation is that this car takes a LONG time to cool down. I suspect oil to coolant heat exchanger is very efficient, and it keeps jacking up the coolant temps until oil is cooled down, and as we all know, oil keeps a lot of heat capacity, and cools down the last.
    • All this made me wonder about radiator upgrade options for these cars, and I found: NONE! Really, no such product in nearly 4 years of C8 being in the market? I'm surely not the only one getting their car run too hot, right?

The car looks sharp and grabs quite a bit of attention. The way I loaded up the car might also be the culprit, since it grabs attention of cars following or passing me on the highway..


There was no visible wear or rub on the wheel liners (both front and back) with Toyo RR 295/30/18, 345/35/18 tires.


Brake pads are also in good shape.



Here's a video of one of the laps I've done right after 2 cool-down laps:

 

Glad you had a great time!

as far as cooling goes. My car is going to a well known shop locally for me here in Georgia for this exact reason.

I drop the car off tomorrow for some cooling upgrades.

I’ll keep you posted

 

I’ve been tracking in pretty warm temps in Texas and haven’t had any temperature issues. I’d recommend burping the system, but I also added a bottle of VP Racing coolant additive.

 

I did it, kinda sort of. Was running Falkens 255/315. After flipping the tires, my tire guy installed one rear tire on the front. So the car was asymmetrical. 255 on 18 inch wheel and 315 on a 19 in front and vice versa for the rear. I never realized it, even after being up close and personal with the tires to adjust pressures and check brakes. Never thought to check tire sizes (why would you). On the street the setup felt fine, but once on the track the car was totally uncontrollable. Went 2 laps and drove straight to a race shop. I thought something was terribly wrong with the suspension, so I was relieved when I found out it was just the tires. Anyway, there was slight rubbing at full lock, but I think a 315 would work. The turn in on the front 315 side was awesome lol. Interestingly, the car threw no codes.

 

So 315s on a 10" front wheel doesn't feel "squishy" on turn in? ... or maybe it's fine on lower grip tires.

 

https://www.corvetteforum.com/forums...from-base.html

 

in stock form the car doesn't overheat because its traction is limited in slow to mid-speed corners, usually you are off power, generating less heat, when you get to the straights, there is plenty of airflow to manage the heat with the skinny radiators (btw if you put those radiators side by side they roughly equal the dimension on a c6 radiator.) Now once you add sticky tires, more power, and better brakes, you are using more power everywhere, generating much more heat in the slow and medium corners, on the throttle longer down the straights, and quicker back on the throttle everywhere. The stock cooling of the Z51 was not designed for that. Have a look at the Z06 cooling, it has 2 more radiators (1 of them is dedicated to engine oil cooling in the driver-side fender, a front center radiator for additional engine coolant, and a more aggressive fan profile. the Z06 Z07 has sticky tires from the factory and GM dealt with it on the front end.

the answer is to install a system that mimics the Z07 system.

 

according to the article the Z06 has 50% more cooling ability than the Z51, get that 50% and that will solve your issue. Also FYI the part number for the center Z06 radiator is incorrect in the parts catalog. I have had my bumper cover off and the bolt holes are there for a bolt-up solution. not going into what I did but if you are interested look at the thread I attached

 

It was on an 11inch wheel.