[cirpower]

Some fun today with the ZL1 on Apex 1LE size tires. Learnings:
- standard alignment works perfectly on this track, 3R tires wearing very evenly
- suspension is slightly too soft, maybe the 1LE rear cradle mounts, lower/harder springs and/or stronger sway bars can help?
- brakes are on the limit, can always brake, but pedal did get really long
- the rear does not feel that planted in higher speed turns, some aero might help?



Any feedback welcome!

[Roostie]

My name's not Amy, but I hope you won't mind me giving some feedback.
First of all, what a great session on the track, very few cars out there! Reminds me of the conditions in my track day last Sunday.

If you modify this car for better track performance, be mindful of your ride quality. Your car is only soft in a relative sense. I have ruined a car or two for the street in search of better performance. Sway bars tend to have less impact on ride quality than springs or dampers, but stiffer sway bars are not always the answer for better performance. With the added grip of the bigger 1LE-sized tires, you might benefit from more bar. I'll be interested to hear what others say.

Your cornering speeds were under 100 mph (with one exception), so I don't think aerodynamics are to blame for what you're feeling, I suspect it's just that you have a relatively mild suspension for a big 650hp car. Which makes it a good street car. And I for one think that tacked-on aero pieces are ugly. The ZL1 looks so good as-is.

If you feel pedal travel got considerably longer, I'd seek recommendations for a pad that tolerates higher temperatures, but don't get pads that are no good when cold because that would be bad for street use. You generally can find specs for the effective temperature range of a performance pad. Your downside of better track performance may be noisier brakes on the street. Look for info on this forum about other ZL1 owner's experience with various pads. This is a specialized question, because there seem to be a lot more ZL1 1LE track drivers than regular ZL1 track drivers.

[LESS1]

Originally Posted by cirpower

Some fun today with the ZL1 on Apex 1LE size tires. Learnings:
- standard alignment works perfectly on this track, 3R tires wearing very evenly
- suspension is slightly too soft, maybe the 1LE rear cradle mounts, lower/harder springs and/or stronger sway bars can help?
- brakes are on the limit, can always brake, but pedal did get really long
- the rear does not feel that planted in higher speed turns, some aero might help?

Any feedback welcome!

Nice laps. With the 3Rs you have added traction which your current springs, ARBs, and possibly bushings are not designed to take maximum advantage of. So the car is going to feel soft. As was mentioned in a previous post you need more spring and or ARB to increase roll stiffness to get the most out of the tires. This of course assumes you continue to run 3R/R comp tires. Stiffer springs will be a trade off for certain. Whereas bigger ARBs will increase roll stiffness without necessarily taking too much away from street drivability. I'm a firm (no pun intended) believer in running softer springs and bigger ARBs. Matter of fact when I begin to modify my car one of the first changes will be adjustable ARBs. Concerning the long pedal, I had the same problem when I ran Motul brake fluid. Towards the end of every session, the pedal would become long from boiling the brake fluid. This went away when I finally located and switched to Castrol SRF. An upgrade to SS brake lines is probably in order as well since you are able to generate more speed everywhere with your new found traction. The OEM brake lines are ok but they do get spongey when you lean on the brakes hard. As for the rear not feeling planted. I'd speculate this is due to the reduced body control caused by your now "soft" suspension from this extra traction.

[TWG1]

Before you chase springs, roll bars, etc, I’d recommend solid cradle bushings. It takes the slop out of the rear and will help you reduce variables going forward. The difference is so dramatic my buddy (Drives ZLE) nearly brought my ZL1 in after a few laps thinking I had something loose out back. I’ve since changed to Delrin bushings and can attest the on-track difference is striking.

[TrackClub]

A question: what do you mean by "standard" alignment?

A long pedal is not pads, but fluid. SRF is the best on many accounts.

Suggestions:
1. Leave the tranny in full auto and you will be faster. That's how all pros drive A10 cars and for a good reason.
Not only does it shift faster that way, but will leave you in a proper gear for best exit.

2. The only couple of times i could see the car get a bit loose was on exits, with aggressive throttle yet much steering lock still present. No amount of mods will solve for it, only a driver mod will (especially given the power and torque involved).

Imo looking at the vid and your PDR inputs from my expert armchair. Whatever 2 cents that is worth
Cheers!

[cirpower]

Originally Posted by Roostie

My name's not Amy, but I hope you won't mind me giving some feedback.
First of all, what a great session on the track, very few cars out there! Reminds me of the conditions in my track day last Sunday.

If you modify this car for better track performance, be mindful of your ride quality. Your car is only soft in a relative sense. I have ruined a car or two for the street in search of better performance. Sway bars tend to have less impact on ride quality than springs or dampers, but stiffer sway bars are not always the answer for better performance. With the added grip of the bigger 1LE-sized tires, you might benefit from more bar. I'll be interested to hear what others say.

Your cornering speeds were under 100 mph (with one exception), so I don't think aerodynamics are to blame for what you're feeling, I suspect it's just that you have a relatively mild suspension for a big 650hp car. Which makes it a good street car. And I for one think that tacked-on aero pieces are ugly. The ZL1 looks so good as-is.

If you feel pedal travel got considerably longer, I'd seek recommendations for a pad that tolerates higher temperatures, but don't get pads that are no good when cold because that would be bad for street use. You generally can find specs for the effective temperature range of a performance pad. Your downside of better track performance may be noisier brakes on the street. Look for info on this forum about other ZL1 owner's experience with various pads. This is a specialized question, because there seem to be a lot more ZL1 1LE track drivers than regular ZL1 track drivers.

Thanks for your valuable feedback Roostie! You are making a very good points on being able to use the car on the street, it is my daily driver and I don't want to ruin it. I agree that the soft feeling on the rear end of the car most likely is not caused by missing aero. Main issue with the brakes is there seems to be air in the system, I did use the Motive bleeder to swap the fluid, but the pedal was not good after the bleed. I am looking into the ABS bleed and possibly bench bleeding the master cylinder, but have not found any good instructions on how to do that. Certainly a more extreme pad would also help the braking performance. I feel the brakes were holding me back, as I was missing confidence in them.

[cirpower]

Originally Posted by LESS1

Nice laps. With the 3Rs you have added traction which your current springs, ARBs, and possibly bushings are not designed to take maximum advantage of. So the car is going to feel soft. As was mentioned in a previous post you need more spring and or ARB to increase roll stiffness to get the most out of the tires. This of course assumes you continue to run 3R/R comp tires. Stiffer springs will be a trade off for certain. Whereas bigger ARBs will increase roll stiffness without necessarily taking too much away from street drivability. I'm a firm (no pun intended) believer in running softer springs and bigger ARBs. Matter of fact when I begin to modify my car one of the first changes will be adjustable ARBs. Concerning the long pedal, I had the same problem when I ran Motul brake fluid. Towards the end of every session, the pedal would become long from boiling the brake fluid. This went away when I finally located and switched to Castrol SRF. An upgrade to SS brake lines is probably in order as well since you are able to generate more speed everywhere with your new found traction. The OEM brake lines are ok but they do get spongey when you lean on the brakes hard. As for the rear not feeling planted. I'd speculate this is due to the reduced body control caused by your now "soft" suspension from this extra traction.

Thank you for the good info and sharing your experience. I might look into sway bars down the road, but I feel I have to fix the brakes now first and given that Chevy changed that themselves, the rear cradle bushings.

[cirpower]

Originally Posted by TWG1

Before you chase springs, roll bars, etc, I’d recommend solid cradle bushings. It takes the slop out of the rear and will help you reduce variables going forward. The difference is so dramatic my buddy (Drives ZLE) nearly brought my ZL1 in after a few laps thinking I had something loose out back. I’ve since changed to Delrin bushings and can attest the on-track difference is striking.

Looks like I need to try those, did you fit them yourself? Looks very painful and I do all my own work in my garage on jack stands....

[cirpower]

Originally Posted by TrackClub

A question: what do you mean by "standard" alignment?

A long pedal is not pads, but fluid. SRF is the best on many accounts.

Suggestions:
1. Leave the tranny in full auto and you will be faster. That's how all pros drive A10 cars and for a good reason.
Not only does it shift faster that way, but will leave you in a proper gear for best exit.

2. The only couple of times i could see the car get a bit loose was on exits, with aggressive throttle yet much steering lock still present. No amount of mods will solve for it, only a driver mod will (especially given the power and torque involved).

Imo looking at the vid and your PDR inputs from my expert armchair. Whatever 2 cents that is worth
Cheers!

Standard alignment means that I have never touched anything, the car is aligned as it came from the factory.

1. My tranny was in full auto with the exception of the end where I was cooling down the car.

2. Good point there, will work on that. I was running in sport 2, might also given race a try next time for the traction control. Really difficult to get all that power down nicely. What a beast!! haha

[TrackClub]

Originally Posted by cirpower

Standard alignment means that I have never touched anything, the car is aligned as it came from the factory.

1. My tranny was in full auto with the exception of the end where I was cooling down the car.

2. Good point there, will work on that. I was running in sport 2, might also given race a try next time for the traction control. Really difficult to get all that power down nicely. What a beast!! haha

I would do a proper alignment on it and bet the car will feel conpletely different balance wise. Sometimes, these cars come with screwed up specs from the factory (uneven side to side etc), besides - and for certain - not with settings even remotely agreeable for track duty.

Surprised to hear you left it in full auto, seemed to me you were downshifting manually, just shows how imperfect judgement can be from a vid. Id leave it in auto on a cool down lap as well. Regardless of low speeds lagging a motor at 1000rpm in 6th gear is never a good idea. Id let it do what the computer thinks is best. Imo.

Yes, PTM Race should give you a bit more freedom on exits, but require you to manage any additional overslip if and when it happens.

Overall a good lap and you push it pretty good
There is a great vid from Racers360 on this track, corner by corner if you think you could benefit from a bit of advice from the pros. And who wouldn't right?

I can certainly see buck 47s (or better) out of this car on G3Rs.
Just do NOT rush it under any circumstances as the car is a beast!!! Cheers!

[VinnAY]

Just on alignment issue my 1LE was toed way out and I couldn't tell it until I replaced my SC3s and saw it on the inside edge of the tires. About 15K miles. I would piggy back with others that the factory alignment work may not be what you think it is.

Hello too from Kansas City as well. @cirpower

[TWG1]

Originally Posted by cirpower

Looks like I need to try those, did you fit them yourself? Looks very painful and I do all my own work in my garage on jack stands....

https://www.camaro6.com/forums/showthread.php?t=546300

The job is painful, but I did it alone and on jack stands with hand tools and a torch. Only time I needed help was from wifey to align factory exhaust back together. I didn’t plan to do the job this soon, until COVID cancelled my HPDE schedule and bought me some free time. The biggest on track difference for me after the mod was on corner entry- the car didn’t ‘take a set’ before the turn, and in corner exit it was far easier to detect wheel spin, since the cradle slop can feel like wheel spin.

But the other posters in this thread are spot on and have given great advice, which I’d probably start with. Maximize alignment and re-assess.

[TheRealJA105]

Originally Posted by TrackClub

A question: what do you mean by "standard" alignment?

A long pedal is not pads, but fluid. SRF is the best on many accounts.

Suggestions:
1. Leave the tranny in full auto and you will be faster. That's how all pros drive A10 cars and for a good reason.
Not only does it shift faster that way, but will leave you in a proper gear for best exit.

2. The only couple of times i could see the car get a bit loose was on exits, with aggressive throttle yet much steering lock still present. No amount of mods will solve for it, only a driver mod will (especially given the power and torque involved).

Imo looking at the vid and your PDR inputs from my expert armchair. Whatever 2 cents that is worth
Cheers!

TC, all the pros are leaving them in auto for the hero laps. You never see a pro video for an entire 20 min session do you? Like i told you in that other thread the 15-17? Z06s were overheating in auto mode. I was just at the track Saturday with one and he overheated in auto and he said he should have been keeping it in manual. Performance shift mode in these autos really really holds the gears for max rpms and downshifts whenever it can which causes more heat than manual mode. Yes auto should be faster.

[TrackClub]

Originally Posted by TheRealJA105

TC, all the pros are leaving them in auto for the hero laps. You never see a pro video for an entire 20 min session do you? Like i told you in that other thread the 15-17? Z06s were overheating in auto mode. I was just at the track Saturday with one and he overheated in auto and he said he should have been keeping it in manual. Performance shift mode in these autos really really holds the gears for max rpms and downshifts whenever it can which causes more heat than manual mode. Yes auto should be faster.

Well, i think there is a difference between A10 and A8 isnt it? Which car did ya see overheat? A Vette or a Camaro?

Agree the pros drive hero laps, but the Ring lap is pretty long and when ZL1 first came out GM pros were giving rides to media all day long...

I have not seen a single post of A10 overheating, but maybe ive missed it? Who knows. I am FAR from perfect, ya know