[Shawnqa800720]

Hi Track-rats. Looking for your thoughts on aero and suspension mods.

I recently switched my 1SS to DSSVs and full SPLs spherical bearings throughout the suspension. I already have the SS1LE swaybars and the ZL1 1LE solid rear cradle bushings. I am running 18" Toyo RR tires on track.

The first time I had the car on track after the DSSVs and SPL, the car was very "slippery" - lots more oversteer and a touch more understeer. I was also 3 seconds slower than my average time and almost 5 seconds slower that a PB day (average at Palmer is 1:45).

I know I need some time to get used to the new setup as it is essentially a new car. That said, I know how aero works so I know it would help in general, but I am feeling like I underestimated the role of the aero working in tandem with all the ZLE components.

My question for you track rats and car engineers is, will the aero take out most of the slippery I have created by making the car so stiff? Or do I just really need to get used to the new setup and the times and control will come??

Thanks Crew!

[cdb95z28]

SS 1LE bars are stiffer than ZLE bars.

At what point of and type of turn are you understeering/oversteering? Entry/center/exit? High speed/low speed? If you are understeering in the slow corners, then yeah, you're probably too stiff up front. Is the oversteer more pronounced on exit, when you are on throttle? Since the front springs allow ride height change, going too low up front can change the chassis balance toward oversteer. A few variables here could be playing a part. If you can't define the balance in the areas described above, then you're not ready to make another change.

What alignment are you running?

Tires act like another spring of the combo and stiffer setups can shock tires. If the tire isn't designed to handle that they are going to give up grip. Aero isn't going to play a big part unless speeds are high. Don't worry about aero until you get the chassis dialed in otherwise you are adding another variable and you'll be chasing your tail.

[Shawnqa800720]

Originally Posted by cdb95z28

SS 1LE bars are stiffer than ZLE bars.

At what point of and type of turn are you understeering/oversteering? Entry/center/exit? High speed/low speed? If you are understeering in the slow corners, then yeah, you're probably too stiff up front. Is the oversteer more pronounced on exit, when you are on throttle? Since the front springs allow ride height change, going too low up front can change the chassis balance toward oversteer. A few variables here could be playing a part. If you can't define the balance in the areas described above, then you're not ready to make another change.

What alignment are you running?

Tires act like another spring of the combo and stiffer setups can shock tires. If the tire isn't designed to handle that they are going to give up grip. Aero isn't going to play a big part unless speeds are high. Don't worry about aero until you get the chassis dialed in otherwise you are adding another variable and you'll be chasing your tail.

Great simple advice to start the conversation. I feel like Tom Cruise in Days of Thunder. I know enough about cars to be dangerous, but need a pit manager to talk me through it all. I car drive the heck out of the car and can feel all the nuances, but don't understand every element. I assumed going with essentially the ZLE setup would have been "out of the box" ready, but clearly I missed a few nuances (SS 1LE sway being stiffer, SPL sphericals being stiffer...)

I'll post the alignment spec later, but I believe I got 3.6 in the front and 2.2 in the rear.

I do feel like if I had more grip out of the tires, the whole setup would have been a bit more magical. I may need to try the Hoosiers with this set up once I wear down the Toyos. I'm not rushing to changes, just thinking out loud. I'll take your advice and find balance in the current setup first.

TBH, the understeer was less of an issue that the oversteer. The understeer was minimally worse than before. The oversteer was far more pronounced, though not "out of control". Just more pronounced than it was previously.

Oversteer was present in a lot of points on the corners:
Slower corners it was later in entry and through center. With good throttle management, I could keep traction on exit.
Faster corners, oversteer was more on center through exit (previously with the car well balanced, this is where I felt the edge of grip and some slip, but not slide. This turned into a bit more slide with this setup and required more careful management).
In both cases, my pace was slower than the previous setup, so I did not feel I was entering too fast or exiting too slow. If anything, I felt I was slower than I would think possible. The non-technical description is that it was looser in the rear where I would normally feel grip was readily available.

I did drop the ride height between 1/8" to 1/4" on the front DSSVs to compensate for the loss of weight on the front due to the supercharger on the ZLE. Possibly did overcompensate, but initially felt this would better balance the chassis given the differential in weight over the front of the car between the SSs and ZLs.

[Baddawg53]

Any chance maybe your tires are just cycled out? The aero shouldn't make much difference in low speed corners, it's all mechanical grip there. Adjustable sway bars could help you balance the car, and add more mechanical grip to the rear. Just a thought ...

[Shawnqa800720]

Originally Posted by Baddawg53

Any chance maybe your tires are just cycled out? The aero shouldn't make much difference in low speed corners, it's all mechanical grip there. Adjustable sway bars could help you balance the car, and add more mechanical grip to the rear. Just a thought ...

Nope - brand new rubber on 18s. I was thinking about an adjustable bar set. Not sure the best one these days. Lots of good and bad written about most. Is there a consensus best one?

[Baddawg53]

Originally Posted by Shawnqa800720

Nope - brand new rubber on 18s. I was thinking about an adjustable bar set. Not sure the best one these days. Lots of good and bad written about most. Is there a consensus best one?

Well I guess it's not old tires!!


There's tons of opinions on sway bars, I know I have the Hotchkis bars and have had no issues. And adjusting them makes a noticeable difference in the car. No issues with the bushings like I've read the BMR has.

[wakespeak]

To me the aero is helpful at higher speeds, >75-80mph. The rear wing does help with oversteer.

However I agree with the earlier poster as well as the fact your times are so much different is that the sway bars need to be matched to the ZLE parts (assuming you have the DSSV/ZLE springs).

Also likely you need to be using the ZLE alignment specs. -3.6 is a lot more than I use (closer to -3). You could be losing too much tire patch. Dropping the ride height affects the corner balance - this is the only reason to adjust it. Sounds like you biased the front end too much (ie oversteer inducing) and affected spring rates too. All together I would go back to factory ZLE specs (or get the car corner balanced) and retest. The supercharger is not that big of a deal on a 4k lb car with driver.

How do you wheels/tires compare to ZLE specs in width? What tire pressures?

[Shawnqa800720]

Originally Posted by wakespeak

To me the aero is helpful at higher speeds, >75-80mph. The rear wing does help with oversteer.

However I agree with the earlier poster as well as the fact your times are so much different is that the sway bars need to be matched to the ZLE parts (assuming you have the DSSV/ZLE springs).

Also likely you need to be using the ZLE alignment specs. -3.6 is a lot more than I use (closer to -3). You could be losing too much tire patch. Dropping the ride height affects the corner balance - this is the only reason to adjust it. Sounds like you biased the front end too much (ie oversteer inducing) and affected spring rates too. All together I would go back to factory ZLE specs (or get the car corner balanced) and retest. The supercharger is not that big of a deal on a 4k lb car with driver.

How do you wheels/tires compare to ZLE specs in width? What tire pressures?

Close to ZLE sizes - 295/30-18 and 315/30-18. Was definitely too high pressure on first two sessions, but around 37 hot after I got the tire wear to run over the sidewall marker by the 3rd session.

The ZLE DSSVs seemed to lower the rear even more than the front, even with the mild drop in comparison to the GM performance lowering kit. The rear sits much lower than it used to and the front seems very similar to previous height. Not saying it isn’t improperly balanced, but on looking, it seems like it would’ve been under steer biased if anything.

Interesting on the camber, but it did feel like a lot of camber when driving normal roads. Worth evaluating also.

As I scientist, I clearly violated good scientific interrogation - I changed too many variables at once attempting to get the SS closer to the ZLE, and now need to peel back the layers to get to best performance.

Does anyone know - with the adjustable sway bars, which give the best range of adjustability to allow me the really work through this experimentation?

[Baddawg53]

Here's some specs on the bars

https://www.camaro6.com/forums/showp...7&postcount=13

[Shawnqa800720]

Originally Posted by cdb95z28

SS 1LE bars are stiffer than ZLE bars.

At what point of and type of turn are you understeering/oversteering? Entry/center/exit? High speed/low speed? If you are understeering in the slow corners, then yeah, you're probably too stiff up front. Is the oversteer more pronounced on exit, when you are on throttle? Since the front springs allow ride height change, going too low up front can change the chassis balance toward oversteer. A few variables here could be playing a part. If you can't define the balance in the areas described above, then you're not ready to make another change.

What alignment are you running?

Tires act like another spring of the combo and stiffer setups can shock tires. If the tire isn't designed to handle that they are going to give up grip. Aero isn't going to play a big part unless speeds are high. Don't worry about aero until you get the chassis dialed in otherwise you are adding another variable and you'll be chasing your tail.

Here is the alignment spec. The rears are higher than I thought as well. I likely told them to max it out, not realizing that the new SPL bits would allow a lot more camber than stock ZLE. Let me know your thoughts... And thanks for all the input so far.

[eimarshall]

That was some toe you had on both ends!

[Shawnqa800720]

Originally Posted by eimarshall

That was some toe you had on both ends!

If you are referring to the "before" values, it was a full fresh install, so everything was pretty out of whack even after trying to match part lengths before installing. We are going to tackle the alignment next week and focus on the toe as well, so it is funny you bring it up.

What are folks running for toe (Is there an alignment thread where people have posted their alignment spec with a brief narrative on its performance)?

[eimarshall]

Im on DSSVs as well and I’m running 3.5f/2.7r camber and 2mm total toe out front, 1mm total toe in rear. I also set my front ride height to match the Camaro Nurburgring setup(692mm to top of front fender lip)

[cdrptrks]

Also keep in mind that the car will lap slower in hot summer weather due to making less power and having less grip when the track surface is too hot. If your average and personal best laps are in cooler weather they're probably not the best reference point.