I've recently traded in my '19 C7 Z06 w/Z07 to get a new '23 C8 Z51 1LT w/ Comp seats, and finally hit 1500 miles with it. I've already sourced all the parts I thought I'd need, and this is my build thread for it.





For reference, my former track build:
'19 Z06 Z07 track build thread

 

Current mods list. THIS POST WILL BE KEPT UP-TO-DATE
(x - not yet installed)

• Engine / Powertrain
  • OEM 2nd AUX radiator (23429489, 23428551).
• Interior
  • Schroth Profi II ASM race harness in black (link). Replacement panels: 84959800, 84959802).
  • Brey Krause R-1130 Harness Bar (11.5lb; link). 68.
  • OEM 2LT+ Visor with HomeLink (84914900).
• Handling / Aero
  • OEM GM High Wing (85001066).
  • OEM GM Rocker panel Extensions ( 84254466).
  • MCS Coilovers 2WR 200 N/mm front, 220 N/mm rear (link).
  • OEM Z06 control arms (85564325, 85564327, 85561499, 85564326, 85561498, 85561497, 85561496, 85564328).
• Wheels
  • BC Forged RZ39 18"x10.5" ET52 Front, 19"x12" ET52 Rear
  • BC Forged RZ39 18"x10.5" ET50 Front, 18"x12" ET50 Rear
  • BONOSS Forged 7075-T6 Aluminum M14x1.5 Lug Nuts
• Brakes
  • AP Racing 9668 372mm front BBK w/25mm pads. (21.6 lb rotor + 12.8 lb caliper vs. 24.2 lb + 13.9 lb OEM; 7.4 lb total front weight savings; link).
  • AP Racing 9661 355mm rear BBK (18.5 lb rotor, 10.2 lb caliper vs. 22.5 lb rotor + 9.5 lb caliper OEM): 6.6 lb total rear weight savings; link).
  • Ferodo 3.12 pads front/rear.
• Fluids
  • Engine oil: Mobil1 ESP 0W-40 (dexos R).
  • Transmission oil: Amsoil FFL4/DCT fluid.
  • Brake fluid: Castrol SRF.
• Other parts
  • EOS extended mud flaps front and rear.
  • MegaLiFe (40+8) Ah battery (16.6 lb vs. 38.3 lb OEM: -21.7 lb). link.
• Weights (of parts not on listed above)
  • Wheel/tire combos
    • OEM PS4S tires and stock wheels: 53.9 lbs front, 67.8 lbs rear: 243.4 lb all 4.
    • APEX VS-5RS wheels with Toyo RR 295/30/18, 345/35/18 tires 47.0, 56.8 lb --> 207.6 lb all 4 (-35.8 lb vs OEM)
• Other / Discussions
  • How-to
    • How-to: Add 2nd Auxiliary radiator (a.k.a. V09 mod) (link).
    • How-to: Fail-proof your NPP actuators for extended (roadcourse) track use (link).
  • Z51, understeer, e-diff, and brake light: Is brushing the brakes a technique now? (link, 471).
  • The hunt for affordable (AP) track consumables (link, 412).
  • A quick analysis on consumables (link, 378).
  • C8 Z51 Track Build v.s. Z06? (link).
  • Pad sizes (volume): C7 Z06 OEM vs AP 9668 vs AP 9661 (link).
  • Missing plastic trim (heat shield) on brand new car.. (link).
  • Alignment:
    • @6/28/2023. 85.
    • @10/26/2023. 338.
    • @6/10/2024. 460.
• Archived
  • APEX VS-5RS 18"x10" ET42 Front (19.1 lb), 18"x12" ET50 Rear (20.7 lb).

 

AP Racing Brakes, Li-Ion battery, front radiator grill guards, OEM Z06 Control Arms, MCS Coilovers



I've immediately run into an issue when I tried to lift the car. The old leave-on-car plastic lift mounts no longer work, since thickness of the side walls of the holes are less, making these plastic pads loose. In fact, I ended up breaking these plastic pads, but had to use them (for one time use only) until I could source my ZL1 Addons metal permanent pads.


Since the lifting points are closer to the ends of the car, it was actually easier the lift the car than C7. On C7s, I'd have to line up the car exactly in one spot, or else the arms would be too long on at least one corner..


MegaLiFe (40+8) Ah battery (16.6 lb vs. 38.3 lb OEM: -21.7 lb)


OEM front/rear tires/wheels: 53.9 lb, 67.8 lb --> 243.4 lb all 4.


Toyo RR 295/30/18, 345/35/18 tires on APEX wheels: 47.0, 56.8 lb --> 207.6 lb all 4 (-35.8 lb vs OEM)


Switched to Regular washers to increase max camber. I like the idea of having a washer in place between the control arm and the frame, but we might end up removing them if we're too limited on camber.


It's amazing how covered the whole bottom of C8 is, compared to prev. gen cars...


Pics of OEM Z06 control arms before I installed them...


I did not see much of a visual difference on the upper control arms, but the lower control arms definitely come with different bushings.


I bought (cheap) radiator grilles on eBay, but I realized they would be way too restrictive. Instead of installing them, I've used them as a template to make my own, using 11x25 mm grill sheet.



Before / After..


OEM extended mud flaps provide a wee bit more protection without looking out of place.


AP 372mm (21.6 lb) vs. OEM (24.2 lb).



AP 9668 (12.8 lb including SS line) vs. OEM (13.9 lb). Total savings up front is 7.4 lb. You might see more savings posted elsewhere; it's often due to brake pad or the bracket, etc. missing in the calculation. The 25mm thick pads are heavier as well..



This was the first issue I've had during the install of my initial mods. Instead of clearing the thread, I attempted to install the new line, which made things worse. I was fortunately able to fix it later on with a thread chaser.


9668 front calipers installed. Looking forward to seeing how the pads fare. I was also trying the quick pad replacement bridge when I took this pic, but later switched back to solid bridge since it should help with stiffness.


Fitment test with BC Forged RZ39 wheels 18"x10.5" ET52. They provide massive clearance.



Fitment test with APEX VS-5RS wheels 18"x10" ET42. Perhaps due to much thicker spoke design, the clearance was much less at about 3mm. APEX seems to look a bit better, though : )



BONOSS Forged Al lug nuts (1.0 lb) vs. OEM (3.2 lb). 2.2 lb savings. The reason I use forged aluminum lug nuts is that they are softer than the lugs, and when something bad happens (cross threading, over torquing, etc.), they get damaged before the lugs. In my more than a decade of using forged aluminum lug nuts, I've NEVER HAD A FAILED LUG. Highly recommended : )


Passenger / Driver sides of rear with wheel liner removed. This plastic trim is missing on the driver side. See the discussion: link.


The top holding bracket for the battery does not fit without removing the handle, but we don't need it anyway; with much lighter weight and the bottom lock holding the battery in place, it is very secure.


Decided to install the coilover reservoirs under the cowl. For the rebound settings, you need to remove the cowl plastics anyway, so why bother installing them in the trunk, occupying cargo space, and also forcing us to cut 2.5" holes to fit the reservoirs through? The coilovers do not come with dry connect, so you cannot disconnect the lines during the installation, either.


T15 Torx bolts and drives are pretty soft. At some point, after bending the first bit, I've switched to using my power drill from low power impact gun, and limited its torque to protect the bit; works much better that way.


Rear brake calipers; they are huge and heavy.


MCS coilovers (12.2 lb) vs OEM rear coilovers (12.8 lb). Their length seem to be identical, so you don't have to drop the height of the car I suppose : ) I say I suppose, since I was not able to get any recommendation on this from Cicio, so I am on my own to decide what is best : )


EDIT: It turns out this location in engine bay COOKS the reservoirs; BEWARE. I ended up relocating the reservoirs to somewhere else (post 272)

 

Continued


Routed reservoir line around that plastic trim. The line is at its max droop anyway, and when the car goes through compression, the line will safely fill the area above the plastic trim, behind the carpet, away from the tire, etc.


AP Racing 9661 355mm rear BBK (18.5 lb rotor, 9.9 lb caliper, 0.3 lb ss line) vs. OEM (22.5 lb rotor, 9.5 lb caliper + line): 28.7 lb vs. 32 lb OEM; 3.3 lb per rear corner, 6.6 lb total rear weight savings. Significant drop in rotating unsprung mass (rotors) is great.


Carefully cleaned up the threads before install to avoid issues I've had up front.


Replacing the pins of the e-brake with offset ones was very hard for me to do, since I did not want to damage the boots by stabbing them, and with grease everywhere, everything was slippery : ) After spending 30-40 mins on the first one and getting used to it, the others took 5+ mins..



The dark colored spacer provides clearance on thickness, while the offset pins move it away from the rotor for clearance on the diameter of the rotor. Anyway, many thanks to Essex for coming up with a solution!


As in the instructions, tried to mimic the OEM line layout as much as possible.


DONE! This marks the end of suspension/brake mods, which was the hardest part. The rest of the mods should not be too hard, and I should be ready for the first track day in no time.

 

Looking good.

 

So you removed about 72lbs but then added some back in certainly with the remote reservoirs. Any weight savings from the Z06 control arms?

Love, love, love the competition seats in cloth. Wish I could've gotten those with 2LT.

 

Going to be a fast track car!
Any worries about engine heat overheating your reservoirs?
Why Z06 control arms?
Any plans for spherical bearings?

 

Thank you! I'm almost ready for track, and looking forward to it! I admit my first few posts have been too pic heavy and not so organized, but that's what happened when I finished most of the work at the same time (i.e. doing brakes while doing control arms, etc.)

Z06 control arms were identical in weight (or too close to call, within 0.1 lb). Lower control arms definitely look different for Z06, but I am wondering if the upper control arms are actually identical. When parts become widely available on other online stores, I'll check. So far, I had to use parts.gmparts.com to locate all the part numbers since the other online stores did not have any parts in their catalogue.

The reservoirs don't add much, if any weight. The coilovers were actually 0.4 lb or so lighter than OEM:


Yeah, I also really like the cloth comp seats. They will hopefully wear better as well. I wish the steering wheel was a circle, but it's fine.

GM engineers mentioned they've used hardest rubber they could use on the Z06 control arms compared to Stingray to reduce deflection with higher traction tires and suspension. If it's similar to how C7 T1 kit's control arms were compared to regular, they might be as much as 500% stiffer. With that, I think they might provide an excellent compromise; not as good as monoballs, but zero noise, zero vibration.

If you think about it, we install the reservoirs in engine bays of front engines cars ALL THE TIME. With enough air flow, they never heat up much. I don't think it will be any different in this case, and at least they will be getting quite a bit of air flow. These reservoirs are supposed to help dissipate heat for the coilovers as well, so air flow would help. I think those indents provide excellent location for these reservoirs, as if they were designed for them : P They are pretty far from the engine within the bay, and are right next to the air outlets. In short, I think it will be OK.

 

Coilover height settings

OEM height of the in my garage (WARNING, it's not completely flat):
FL/FR/RL/RR from the ground, in mm):
700/690/723/730

Since my garage surface is not leveled, I am not too worried about the variances, and I only moved coilover heights in EQUAL AMOUNTS on both sides. This is something I've learned when I tweaked coilovers in C7, where I've transferred weight to one of the diagonals by mistake, severely messing up settings. The final settings will be done by the race shop handling my alignment + corner weigh balancing.

Avg. OEM heights: 695 Front, 725mm Rear.
Target with 15mm drop: 680mm Front, 710mm Rear.
Target offsetting Toyo RR diameter differences: 670mm Front, 714mm Rear.
*****Coilover perch settings to hit this ballpark:

• Front: 70mm from the bottom thread to where the load bearing perch starts.
• Rear: 165mm from the bottom thread to where the load bearing perch starts.
• I wish someone gave me some ballpark settings like this, so I'd not have to do many 'experiments' and measurements : )

Justification: Since I'm using much smaller diameter front tires, the total front height drops by another 10mm just due to tires, and I need to take into account. One might argue I should actually optimize for the tires I'll use, but I plan to keep the OEM rake in suspension, and this way, it will also work well when I use 315 fronts. Besides, more rake created by 295 front Toyo RRs likely only help reduce front understeer.




Played around the coilover heights and took notes to understand how it behaves.


Getting close...

OEM GM high wing


Before I put the tires back, decided to get done with the high wing as well.


It's probably not mandatory, but you'd need to clean the old adhesive for a clean install of the high wing, which already comes with its own.


Thankfully, I always stock various adhesive removers.. : )


Done! I'm really liking the looks..


Another angle; looks great!

TODO:
There's so little left to do:

• BK harness bar + harness adapters on the seat
• Side skirts
• Engine and Transmission oil and filter change
• Alignment

 

The vs5rs in that color with hypersonic looks outstanding. Looking forward to more pics when you're done. Planning on going with big aero at some point?

 

Moving quickly! Personally I think it would have been more interesting to track the car stock and then move forward with the parts cannon just to understand the progression, but I also get wasting no time! Curious to hear your impressions coming from the C7Z. I find the C8 a very easy car to drive at 8/10ths. At 10/10ths it's all about understanding how to leverage all of the weight behind you, which is an unsettling feeling coming from a FE experience. The car is surprisingly tail happy with most/all of the nannies turned off and I've gotten into few tank slappers that took more than expected effort to correct. A very very different driving approach but a new skillset for sure. I enjoy casually tracking my C8 but if I had to pick one it will still be the C7Z all day. C8 is a significantly better road car in everyway, though; which I get is not applicable here.

I would suggest trying to minimize AIT and to an extent coolant temps. Oil temps are already well managed. Now that the heat has settled in here the car is much lazier in the heat; was very crisp in the cool. Would also suggest moving to the Supercar 5w-50.

Now that tuning is an option are you going to explore that?

 

Thanks for your insights!

Re: trying as stock, I like that idea, but I always think Z51s, especially ones with no MRC like Miatas: very soft sprung, and not ready for any high traction tire. On the top of that, you also cook brakes. As such, I've decided to put in the goodies even before trying it as stock this time. I did drive the Z06 quite a bit in stock form (but with race pads, etc. of course), and it was great! In fact, with Z07 package, it was very very close to what aftermarket stuff can muster.

I've been using my left foot for braking on all our cars since I bought this car, and I'm still a bit more harsh than I used to be using my right foot; old habits die hard! In a panic scenario, I still slam the brakes harder than I should (had a few cases when someone cut into my lane in traffic, etc.). Anyway, I fear it will be a slow curve to get back up to speed at the track with this new rear engine setup, as well as left foot braking, etc.

Yeah, Corvettes are always slower on hotter days, except if you can cheat like @Nabush can do with E85 : ))) I plan to leave the engine bone stock, especially considering the very tight tuning it needs to work flawlessly with the transmission to prolong its life, and I don't really want to touch that.

Is 5W-50 even recommended for these engines? I thought I saw the recommendation only for the Z06 (LT6).

 

Good to see your progress and curious to see how the car will fare !

Looking at your pics looks like your wheels are standing out a lot in front and may rub the fenders ?

You went really high on spring rates, your C7 was 140/130 right ? Mine is 130/120 and it is too soft, I will change spring rate next year. Suspension geometry is different so springs rates might not be comparable vs C7 though...

 

Hoping to see you in July at ORP; definitely trying my best to be ready by then : )

The spring rates are also 4x (!!) the stock spring rates to be honest, but these are the rates Cicio performance recommends, and they have been recommending it to others, too: I asked for setup for slicks, and this was their recommendation. A friend of mine asked for a setup for 100-200tw tires, this was their recommendation for that as well, and others here also got the same rates. Anyway, MCS coilovers can work well with stiff springs, and hopefully it will all work out, and it seems to be doing well for some of the other C8 owners; we'll see!

 

The track setup guide still says 15w-50 is an option for track only. That's actually cheaper and easier to get than the 5w-50 but a few LT4 guys I've been running with have switched over to it. I'm now running it in both cars.

 

Yeah, it doesn't look like 5W-50 is recommended at all for LT2. I think it'd be best to stick with 0W-40. Bearings and clearances are different between LT2 and LT6, so they might have different requirements anyway. Speaking of which, I suppose I can do a few oil analysis tests to see how it's doing, but I know that LT1 was pretty happy with 0W-40 : )

EDIT: Updated track prep doc:
https://www.chevrolet.com/content/da..._081722_v5.pdf

 

What are the spring rates? I would run the 5-50 Supercar. The weight is just slightly higher, and it is Dexos 3 approved.

 

All the specs are usually in the mods index post:
https://www.corvetteforum.com/forums...post1606753779
Front 200 N/mm, rear 220 N/mm : )

Oil needs to be both a recommended standard and recommended weight; I am not able to find 5W-50 being recommended for LT2, and it might become a liability. As they did before, however, GM might later update recommendations for future C8s as well as (retroactively) former MY C8s and add 5W-50 as a recommended oil for for base C8s as well. That said, since the docs are already updated for Z06, I'd doubt that they would do so.

 

If the track guide recommends 15-50 I doubt the 5-50 would be an issue. The 15-50 will eventually foul cats if used long term. IMO using the 0-40 on the track is not a big deal since the LT2's are relatively inexpensive.

The spring rates are not necessarily too high. I run 700/400 on my dual duty car which weighs 2400lbs. The front to rear rate bias is a bit odd though. In actuality the spring rate is not a good metric. What is important is the wheel rate.