Racin Time

After reading the Super Stock C6Z versus C5Z tread it sounds like there may be more C6Zs show up for 2009 nationals. I'm looking for discussion on set up for C6Z such as alignment, shocks, front sway bar, ride height, tire sizes, etc. to name a few, that some of you C6Z drivers have tried. Remember this is for autocrossing (solo 2) type events not track events.

gtldvm

I guess I'm interested in the same information. It seems to me the popular tire sizes for SS is 285 or 295's up front, and 325's to the rear. Apparently going with the 345's to the rear is negatively affecting the handling. I'm interested in the Koni 2812's, custom valved, and the Pfadt adjustable front sway bar. I think a lot of downshifting is going to be needed, so get real good at heel'n'toe downshifting.
Of course, this is what I'm looking at. Those competing successfully can chime in with their setups, and save us some money by telling us what DOESN'T work!

0JoshS

We have been working on a SS Package for the C5, C6 and C6 Z06. We have developed a SS specific front sway bar package that gives you at adjustable sway bar that is matched to your specific factory rear sway bar.




We have also been having great success with our Sport Shocks in Super Stock. The Sport Shocks feature simple damping adjustability that allow you to change the corner entry and corner exit balance of the car. They also feature an inverted design that reduces the unsprung mass of your suspension, this allows the suspension to react to the road surface more effectively which gives you better traction!




See what one of our customers had to say about the SS Package...

Click Image

Please let me know if there is anything that I can help with!

gtldvm

Josh, please re-read my post...I already mentioned/promoted your adjustable swaybar. I am familiar with your shocks, as I have visited and extensively read your website, and I have given consideration to your shocks.

Thanks for your input. I look forward to developing my car at some point, and I'm open to all suggestions.

Racin Time

After Chris Ramey sold his 07 Z06, I bought the wheels and tires he was running on the car. He had Hoosier's A6 with the 315/18 on the front and the 325/19 on the back because he felt the car was pushing too much. Since then I ran this wheel and tire combination on my 07 Z at several events and found my car was fairly neutral with the factory alignment. I checked the alignment from the factory my car had -1.5 in the front with -.09 in the rear for camber with +1/8" toe in the front and back. I plan to do a much more aggressive alignment on the car this spring and then I'll see what the car does.

gtldvm

Interesting. I just had Danny Popp align my car...I believe there is a slight toe in in the rear, and 1/8 toe out up front. Let me know how things change with the alignment. Right now I'm changing the setup on my C5 convertible Z06 (ASP is a wonderful thing) and i'll campaign it one more year at least. I'm hoping we can get the C6 Z06 worked out for 2010 season.

Racin Time

My plans are to increase the front between 2 to 2 1/2 neg. and the rear may go to 1.2 neg. I plan to put in 1/8" toe out in front and leave the 1/8" toe in on the rear. I'm thinking this is going to increase more oversteer and to off set that I'll want to switch to the 345/19 on the rear. I also have my Koni's to put on. Running on concrete hopefully I can put that 505 hp to use.

gtldvm

I hear you about using the ponies. I am a little troubled that more C6Z's aren't on the national scene. Some say it can't be tamed or setup to work, I'm wondering if it just needs to be driven differently and set up differently. I've considered that with so many going to bigger front sway bars, perhaps this is the wrong direction. I'm putting custom valved Koni 2812's on my C5 now, and Koni is going to use my C6Z as a test pig for their FSD shocks, giving me the shocks and my OEM's when they're done (Koni USA is literally a mile from my business). I am hoping to take both cars to a test'n'tune in the Spring to drive the well setup C5 and compare the C6Z to it and determine what feels right. We'll see. I still like the Pfadt adjustable sway bar up front. Next I have to get wheels/A6's and make the alignment more agressive. I like your idea of 1/8" toe in for the rear, but I would think that would make it push more, but I am no expert on setups...I have Danny Popp for that. I will share this with you: I took my C6Z to Putnam Park in stock trim on OEM street tires and pushed the car very hard, pulled 1.08 G's regularly, and really hurt the tires. The thing is this, the left rear fell out of alignment to the tune of 0.79" toe OUT! Putnam Park has 8 right hand turns, and only 2 left hand turns. I can tell you the car actually turned better with the toe out in the rear (at least when I turned to the right). Just a thought. Maybe someone can explain to me my perception or the error thereof.

Racin Time

I've been told by some of the road racers that they actually run some toe out on the rear.

TedDBere

Toe-out in the rear will help the car rotate on the turns, but it can make a rear wheel drive car squirly when you put the power down. FWIW.

Most vette drivers run tow-in in the rear to reduce the ovesteer on powerdown corner exit. When the car squats upon power accelleration it actually toes out a little, so the static toe-in counters this change upon powerdown exit.

But still, you may be on to something with the C6. Only testing will help find out the answers. So far using the C5 tuning tricks on the C6 haven't been found to help it all that much. Good luck.

JiminVirginia

I've installed the Pfadt hardware Josh is decribing. I've only done one event with this setup (using 295/18 and 345/19 Hoosier A6s). I felt like I wasn't pushing the car enough, though I did fine from a competitive standpoint. There is more capability in the car now, and I need to explore it more. Maybe I need to drive it a little differently; I'm a recovering C5 Z06 driver.

One dilemma is finding the right setting on the Pfadt adjustable front bar, so the car turns in and avoids mid-corner understeer but is simultaneously planted when you put the power down coming out. I'm going to try "one more hole" on one side and see what happens. I'll also try some more toe out up front. And playing with the shock settings: softening the fronts seemed to help in the one chance I'd had to run the car with all this stuff on it.

I'm skeptical that there is any gain to be had from downsizing the rear tires from the 345s. Losing grip at one end to help the other end is sub-optimal at best. Plus there isn't that much steady state cornering in autox.

I had not thought of trying 315s on the front. 315s would raise the front a third of an inch. Not much. I assume the 315s fit?

Racin Time

The 315/18 fit on the front of a C6Z with stock oem rim sizes just fine.

Here is a tread on the SCCAForums.com you might be interested in reading. It pertains to setup of C5Z for SS.

http://sccaforums.com/forums/thread/334487.aspx

Racin Time

Here is some information I find very usefull. This should explain how tire sizes etc effect handling.


Understeer : The tendency of the front of the car to "push" when negotiating a corner (car wants to go straight)
Oversteer : The tendency for the back end of the car wanting to come around (car wants to spin)
Neutral : The car neither oversteers or understeers

Most cars are designed from the factory to understeer, as it's safer for the general public. If you go into a corner too fast, the first reaction is to usually hit the brakes. If it's a car that oversteers, hitting the brakes (usually) will bring the tail around and spin the car. Not usually considered a good thing. If it a car that understeers, hitting the brakes will generally slow the car and allow it to negotiate the corner.

High Performance Handling Chart

To Decrease...........To Decrease
Understeer..............Oversteer....... ....Adjustment

Higher.....................Lower........ ......Front Tire Pressure
Lower.....................Higher........ ......Rear Tire Pressure
Larger....................Smaller....... ......Front Tire Section
Smaller...................Larger........ ......Rear Tire Section
More Negative.........More Positive......Front Wheel Camber
More Positive..........More Negative.....Rear Wheel Camber
Toe-out.................Toe-in...............Front Toe
Toe-out.................Toe-in...............Rear Toe
More Positive..........More Negative.....Front Caster
Soften...................Stiffen........ ......Front Springs
Stiffen...................Soften........ ......Rear Springs
Smaller..................Larger......... ......Front Anti-sway bar
Larger...................Smaller........ ......Rear Anti-sway bar

JiminVirginia

That's a great summary chart. And it makes me wonder how much caster adjustment we have for our cars (C6 Z06). I have not tried to maximize it, but maybe I should. Would it make much difference? (???)

As for the SCCA Forum thread, yes, I saw it, and these guys have pretty much written off the C6 Z for autox. It is informative, though.

talon95

Remember that changing toe is an "analog" adjustment, not a switch going on and off. Going from 1/8 out, to zero, to 1/8 in just steadily decreases rotation (increases understeer). Where you end up depends on all other setup factors (rest of the alignment, shocks, bars, tires, surface, etc...). Also depends on your driving style. If you have good throttle control, you may be able to tolerate less toe-in for example.

Hard to say where you'll really end up on a C6Z though. It has the big wheel offset which suggests you might want less toe-in or even a little toe-out, but then it has that big rear bar also. Just have to test and see what works.

Dave G.

poser

wow, i didnt know 315s fit on the front...i always thought 295s were the biggest size one could run on the C6 Z06 in stock trim...

anyone else using this combo??? if it works, i'll switch to that next season...

i just installed my pfadt shocks and front swaybar...next race is in 2 weeks, so we shall see how much i'll need to adjust my driving...

TedDBere

Chris had two sets of rims. One stock and one not. I'd check the rims with the 315s on them because those were the sizes he had on is non-stock rims. FWIW.

90pololt4

One thing I have not seen mentioned, is the difference 1 or 2 drivers, in the same car & class can make. As one can see from the results for years at events, 2 driver cars have a big advantage. So when setting up the car does one tune it for moderate tire temps or optimun tire temps. Where I'm located, we can go from 40's in the a.m. to 80's in the p.m. The 2 driver setup helps to even out the tire temps, getting them up there faster and maintaining them. This can change how the car is setup. Othe ideas?

TedDBere

The only change ambient temperatures make is the starting tire pressure. If you start lower then there will be more flex in the tires and they will heat up faster. I'm not aware of any other setup changes that are needed for one driver cars as compared to two...except more gas for the two driver car.

Racin Time

Ted the 315/18 were on oem C6Z polished wheels and I have made at least 30 runs on them with my 07Z with a lowered ride height and I have not had any problems with the front rubbing.