Ksteckba

It’s also worth noting that many people have mistaken ice mode for the ESC withholding braking when some steering angle is present (not saying it is in your case, but I don’t know the particulars of your instances of potential ice mode), and the ESC could be more sensitive with more grip...

Farva0066

OMG I can't thank you enough. Even on this forum it can be difficult to find info about actually tracking the car (lots of posts about 21" wheels, etc...), this is amazing -- and surely lots of work to photograph document everything on your end.

I did the same thing: base z51, go from there. Want to get a feel for how the base car performs before I start adding stuff tho -- 1st track day is at Palmer in Massachusetts in a couple weeks.

Just wanted to say thanks. Thread bookmarked - excited to check in!!

96GS#007

@X25 has been amazing through the years documenting his car modifications. Many of us have benefited greatly from him sharing his experiences

X25

Thank you all for your kind words! Corvette forum has always been an amazing site for the community, and I'm very happy to be a part of it.

On a side note, every time I start a new build thread, I think to myself that this time the thread will have to be very short since they say GM 'took care of everything', but then I stand corrected : ))))

Coming up next: a short how to on heat-isolating AFM exhaust flaps; they keep throwing check engine light when they get hot, and I'm guessing I'm probably not the only one...

X25

Quick update

Parts debacle
TPMS sensor debacle
When you look it up, 13538759 and 13554170 show up as the TPMS sensor for C8 Corvettes. Well, an expensive lesson learned, 13538759 is NOT the right part! It is listed to work on Cadillac XT4 and CT5 as well as Stingray and Z06, but it definitely did not work on my car. 13554170 is the correct part.

Exhaust vale actuator debacle
In the same manner, when you look up for exhaust actuator vale, it shows two numbers: 85151128 and 85520525. 85520525 is the correct part, and used on both sides.

TIP: What I learned: when you're not sure, always check for fitment at parts.gmparts.com. That site knows the right parts : )

Area27 experience
It was great fun to drive at the Area27 again! I used CR-S tires for most of the event. When I switched to the Hoosiers before the last session, I realized the TPMS was not working, and it was quite distracting to drive with all the lights on the dash. Anyway, I was hitting 2:26s last time, and got it dropped to 2:22s this time, but there's still a long way to go:

The video from the recent event:

The video from my last time with the C7 Z06:

• I've been using my new baseline 9C/12R during the whole event. I tried 9C/14R for a few laps, and it was slower, and I reverted right back for the time being. I will experiment more on this only when my times no longer improve, so I can better gauge the difference.
• 2:22 is still a far cry from 2:12 I was making with the Z06, which I'm sure is not the best that can be done with that car, either. Anyway, with everything off, I'm still pretty happy with how easy it is to manage the car, and here's hoping I can drop more time.

Exhaust flap issue
I keep getting check engine light code P31D8, etc., which indicates the AFM actuators are failing. This issue only happens when they get very hot, and I immediately clear the code since I don't want the check engine code on during track sessions. This would make it tricky to repro at the dealer, and I frankly don't want them to touch the car if I can avoid it. So, I decided to order the replacement parts.




The new one up front, and the old one in the back. Correct part number is 85520525.


There's an insulating layer for the actuator, but I think it gets squished and gets too close if the bolts are torqued too much. In order to always maintain a good space, I decided to add a thick washer in between.



This is how it looks! I'm pretty hopeful that this will solve the problem; we'll see! If it does, I'll write a quick how to about it. If not, this is likely the last time you're reading about it.. : )

CAINCA

I wonder if it would be better if there was an insulator between the actuator and exhaust. Maybe a ceramic washer like these would be a better choice:
Extreme-Temperature Ceramic Washers at McMaster-Carr

It looks like there is more thread on the mounting bolts too. Maybe you could double up the washers to create a bigger air gap.

Do you have to take the bumper cover off to access these?

X25

Those washers look nice. Don't know about their thickness, though. The space is actually maxed out by the actual actuator arm limiting that opening. Looking forward to seeing if this helps, and if it does, you can definitely improve on it with those washers. You only need to remove the rear mud flaps and pull the liner aside to reach at the actuators; pretty easy.

Does anyone else also suffer from this issue? I'm sure I'm not the only one : )

Brake pad wear
I'm trying SR21 pads for the first time on this car. The brake feel was good at the track. I've had to do an emergency exit due to a passenger stating they're about to puke, which probably put a 'rainbow' on the pads, but other than that, I always took the time to do proper cool down as well.

I see abnormal wear on driver side front outer pad. I've replaced that pad with a spare pad, but this is concerning at only 3 track days. All other pads look good. Not sure what would cause this. Ferodo 3.12 had an uneven wear as well, but I had to replace them after 10 track days' worth use, not 3.




Driver and passenger sides... Looks good except that one pad.


Rears look good.



Replaced the abnormally worn pad with a new one.


Not sure what's causing this yet, but I'll definitely keep an eye on it. It'd be great if Raybestos would come through and send my ST47s : )

Mark9

I had the car throw codes for both valve actuators at the first track event of the year. I needed to disconnect the battery in order to clear the CEL. My code reader said it cleared them but the CEL persisted. Didn't affect anything on the session when the CEL was set. Didn't happen during the last track event which was about twice as much time as the first. I won't disconnect the battery again as three of my TPM sensors didn't register until I was almost out of the paddock and getting on the track. More of an issue with TPMS not registering than the NPP valve codes.

X25

I can easily clear the codes with Torque app on my phone without disconnecting anything. If you have a Bluetooth OBD-II bongle, I'd highly recommend it! I only replaced one of the actuators (the second one is in the mail), but I don't even know if the original actuators went bad anyway, especially since they seem to work fine when not very hot. It very consistently reproduces for me, so I'll probably know real soon if it works or not : )

Mark9

Pressure imbalance within the caliper perhaps. That much wear difference would make me suspect only one side of the caliper is pushing the pads. I'd contact the caliper manufacture and discuss.

X25

I've contacted Essex, and they asked a bunch of questions. I'll share the info if they provide any useful tip. In the meantime, I'll monitor the pad wear, and I'm also thinking about putting on temp sensitive tapes to see what temps each side of the calipers hit, etc.

In other news, looks like I'm wearing down both front and rear tires on the inside! For the first time after owning so many different cars, looks like I might have used more camber than needed! This feels wild to me, considering I always got the shoulders to wear first on other Corvettes. The suspension must have a very aggressive camber curve... yay! I will get alignment done again, and I will pull the camber values from -3.5 / -2.5 Front/Rear to -3 / -2 as GM's track guide also calls for.



Front tire; left is the inner side. Observe the threads getting very shallow..


Rear tire, and far side is the inner side. It's almost hitting the wear bars!

X25

The hunt for affordable brake (track) consumables

The prices for all consumables have gone way up lately, and considering I've so far have not been impressed with SR21s on the car, I've spent whole last night searching for better pricing for the consumables. Here are some findings.

• Brake pads
  • Ferodo 3.12: These pads lasted ~10 full track day's worth, which is on par with what I was getting from C7 Z06 ST47s. Considering I had much more wear on the inner pads up front, I could possibly rotate pads mid-way by 5-6 track days or so, and get even more life out of them. Alas, the pricing is very high for these in U.S. Fear not, they are much more affordable in UK, and they shipped for ~$35/set : )
    • Fronts (FRP3014G):
      • US list pricing: $676.
      • UK pricing: $444.
    • Rears (FRP3144G):
      • US list pricing: $602.
      • UK pricing: $406.
  • EBC SR21: So far I've used these for about 3 track days, and I have had expected wear, similar to Ferodos on all 3 corners except on my driver side front. I am still trying to figure out if it's an issue with my car, or if that corner just runs tiny bit hotter, causing this premature wear, but we'll see.
    • Fronts: $330 (list $380).
    • Rears: $323 (list $386).
• Rotors:
  • AP: AP rotors have so far been holding up fine, but it will hurt quite a bit when it's time to replace them. What's more, I can't see much better pricing than list anywhere, and I'm guessing we only have one supplier for these. Some dealers might have small discounts and free shipping, so there's that.
    • Fronts (CP7177-351GC/350GC): $549 list. $1098/pair.
    • Rears (CP7177-211GC/210GC): $529 list. $1058/pair.
    • UK sites: I could not find exact replacement rotor rings during my search last night, but similar AP rings at similar shapes were around $600-800 range (example).
  • (EDIT: Might be Chinese knockoffs) Alcon Kits / Paragon: These folks have a replacement ring for AP kits. They look good quality, and the pricing is significantly better! I have not tried these, yet, and I already have a spare set before needing a new spare set, but wanted to let you folks now of existence of these rotor rings : )
    • Fronts: $720/pair.
    • Rears: $610/pair.
    • Their full list for all AP rings is here: link.

Note: I'll share this in autocross site as well, so folks would know about these alternatives (link)..

oooseun

Thanks for the research and results @X25 !

Seeing similar wear on the same tires with similar camber. I don't think i'm convinced it's camber though as i'm still chewing up the outside of the tire as well.

What pressures are you targeting hot on track? What do you start with?

I'm usually starting with 24/25.5
targeting 32/34H




Inside edge (top) not too worn, but increases dramatically towards the 1st line at the top then tapers off. Old picture, this was on 4 day CRS

Fronts by comparison with more camber.

Rears (3 day old tires) same camber, showing lots of outer edge wear

X25

Thanks for sharing! Could you please remind me if you have coilovers, or if you're running OEM suspension? I think that would play a big role in determining this. The longer stroke and softer springs of stock suspension would cause a larger delta in dynamic camber, toe, etc. when the suspension is loaded vs. not, and coilovers with the lowered height probably start from a more aggressive camber curve as often is the case with unequal length control arms. Not sure which one wins out in terms of causing this wear pattern : )

I run ~22-23 PSI both front and rear at start, which hits about 30-32 PSI hot in a session.

Mark@AMT Motorsport

You think the AP hats just bolt up to those discs? Never heard of Paragon brakes, but for about half the cost of the AP rings I might give em' a shot. I just replaced my front and rear assemblies (ouch) and I bought a complete extra set of hats and hardware, so I'd swap the original stuff in to those discs if it all bolts up.

X25

Yep, see their full list of applications that I've also shared; they have a replacement for pretty much every AP application. I'm sure they'd have one for the larger 390mm rotor ring, too, for those who have that kit. If you end up testing them out, please let us know : )

oooseun

NP!

Still on stock magride. Fully lowered (pain) -3.x(4?)F/ -3R
I have afe sway bars as well.

X25

I see. My big guess would be that I think you're eating up your shoulders faster due to softer suspension, despite help from the bars, and you're wearing insides as well due to too much camber, which is ironically still not enough during hard cornering, leading to shoulder wear. I don't think it's too low tire pressure. If you own a pyrometer, you can take measurements and eliminate some of the possibilities.

I do own one, and should use it to figure out how my setup fares, but I need a second person to help out in hot pits for it, and I don't like asking favor from people. Perhaps I should ask for help next time...

Anyway, I think I have too much camber, especially in the rear, judged from even more pronounced inside wear over outside. I'm currently at -3.5 / -2.8, and I think I'll pull them 0.5 points back, to -3 / -2.3, or perhaps GM's recommended -3 / -2. If I get a chance to have someone with me during one of the events, I'll collect tire temp data, too.

Mark@AMT Motorsport

Hmmmm. Appears this is Chinese knock off stuff. I'll stick with AP rings in that case.

X25

I see, good to know! They're quite affordable, more than I thought, and that might be why as well.

I'll mark the original post with this possibility.