acrace

All:

It looks like I am going to try an '09 Z06 for Super Stock next year. After taking 2010 off from autocrossing and running a Solstice Z0K in '08 and '09, I'm looking forward to getting back into a Corvette.

I did some Forum research and found these threads to be informative:
http://forums.corvetteforum.com/auto...oss-setup.html
http://forums.corvetteforum.com/auto...-for-ss-2.html
http://forums.corvetteforum.com/auto...ersus-c5z.html
http://forums.corvetteforum.com/auto...the-c6z06.html

But I thought that I'd like to revisit this, as it's been nearly a year and a half since there was any good discussion about setting up a C6 Z06 for SCCA Solo Super Stock.

Tires:
1. Is the 315/30-18 front and 345/30-19 combination the "preferred" choice? What's the advantage of a 315 up front versus a 295 and how about 325 vs 345 opinions for the rear tires?
2. I see some folks say that they had no interference problems with the front fender or liner with the 315/30s up front, but I'd like to get additional opinions. Scarfing up a carbon fiber fender and replacing it isn't in my budget.
3. Any tire pressure recommendations as a starting point? For any of you who ran a C5 Z06, how different were your pressures between a C5 Z06 and a C6 Z06?

Lowering:
1. Opinions on how much? For now I will start on the OEM shocks and we'll see what my budget calls for in terms of upgrades, but I really don't want to be slamming the shock bump stops.
2. How about rake? Any recommendations on keeping the same front-to-rear relationship or how about a more level rake?
3. Does one lower a C6 the same way as a C5? It's been several years since I've tinkered with the adjusters on my C5 Z06. I'll have to look at my notes.

Alignment:
1. I was going to start out between 2 and 2.5 negative camber up front (with zero toe) and approx 1.5 negative in the rear (with 1/4" total toe in). Any thoughts on going more aggressive on camber or is this too much? I'm reasonably certain that I'll wind up with toe out up front, but zero toe, for me, is always a good starting point for my first event.
2. The first thing that I did when I got my C5 Z06 was to remove the washers behind the upper control arm bolts. It seems to me that, under just a cursory peek, that there are more washers or shims on my C6 Z06. Someone told me that each washer was worth about 0.5 deg of camber. Any confirmation or opinions? I guess the summary is . . . should I take out all the washers?
3. If I recall, when I did my initial alignment on my C5 Z06, I cranked the rear lower control arm eccentric to full negative camber and then fine tuned with the front lower control arm eccentric. Is this still the way to do it with a C6 Z06?

Fuel Level
1. How low can I go? I was able to run my '03 on fumes (if I wanted to). Is the C6 Z06 capable of that, as well?

Any other ideas? I'm not going to play with bars until I have some seat time and isolate the driver from the basic set up. I see that Pfadt bars are getting popular for SS cars (whether C5s or C6s). Any other thoughts? I had the Addco 32 mm bar for my C5 Z06.

I'd appreciate any thoughts. I'd be happy to reciprocate with any learnings.

TedDBere

What happened to the C5Z?

acrace

It moved over one bay in the garage. It's my "Plan B".

Racin Time

The C6Z seems to have an understeer problem and the 315 in front helped that problem.

The 315 on the front just barely scuffs the front air duct and interfender. I have not had any problems with the outer fenders.

I've been running 32 front and 34 rear. At nationals I was experiencing a little more oversteer so I bumped the rear a couple of pounds. Now that I've had a chance to run the car with oem shocks this year, I plan to install my Koni Shocks hopefully they will make a difference.

Lowering the front and the back on the C6Z is the same as the front of the C5Z. I don't believe lowering the car all the way down is recommended. I lowered mine about half way. Please note due to the rubber on the adjuster bolt conforming to the lower control arm. I recommend full turns on the adjuster bolt. This will keep you from experiencing a ride height change later. I tried to keep the rake the same as factory.

Alignment settings are very similar to the C5Z

No problem with running a low fuel load.

Solofast

Al,

My DA Koni's have been revalved (Sam said he likes this valving) and are off the car right now. I am betwixed and between if I want to sell them or put them back on and run them next year. The adjustment range is plenty wide enough for the C6Z and they are shorter by a bit in the back so that you won't bottom them out ever.

We probably should talk and see if you want to try them.

If you lower the back too much the rear won't hook up coming off of corners and in a C6Z that's real important... Just a thought on how low you want to go.

acrace

Solofast:

Yeah, e-mail me. My work e-mail address has been the same for a long time, so you should have it. Otherwise PM me. I would be interested in your Konis.

I agree, making sure that you're not on the bump stops is critical, whether it's a C6Z or a C5Z.

Solofast

Al,

Will do it's in my outlook on the work computer, will chat tomorrow..

CorvetteZ51Racer

I haven't tried mine with 315s in the front. What I have is the Pfadt SS front bar, the Pfadt Inverted Sport shocks, harnesses and pads. I ran 2.6F and 1.9R camber, with 1/16" toe in out back and 1/16" toe out in the front, front bar at full stiff, front shocks at 14 out of 16, and rears at 10 out of 16 (16 is full stiff on the Pfadts). The car was VERY neutral, no turn-in issues, no mid-corner washout issues, no power down issues. The club I've run with in Texas does "practice" auto-xs in the summer, where you get to run as many runs as you and your car can stand for $15 per day. I did my test and tune with the shocks/sway package during one of those practice events. With the Pfadt setup, the car was 2 seconds faster than with stock shocks and front bar, and was easier to drive.

Racin Time

How long did it take you to change sway bar and shocks at the event?

What tire pressure were you running?

#63 SS 07 Z06

CorvetteZ51Racer

Ok, I should clarify. When you talk to Aaron, he'll give you the "equivalent settings" to the stock hardware. I had the Pfadt stuff on when I arrived, but it took about 3 hours to install all of it at home. The "equivalent settings", IIRC, are full soft on the sway bar and 10/10 for the shocks F/R. Full soft on the sway is still stiffer than the stock front bar, but I had to go even stiffer to get rid of the mid-corner wash-out, so IMO it's close enough to being a "stock" to Pfadt comparison.

acrace

Racin Time - thank you for your detailed comments. One question about the understeer you mentioned. Was that during turn-in or steady state? Did you experiment with softer sway bar bushings or different bars?

acrace

CorvetteZ51Racer - help school me. I was always taught (and it was certainty the case on my C5 Z06) that a stiffer front bar would increase understeer. So I find your comment about stiffening the front bar to get rid of mid-corner wash-out (steady state understeer). Any thoughts as to why that was the case? It just seems counter initiative to me. I'm not trying to argue, just trying to learn.

CorvetteZ51Racer

I've always been taught the same thing. However, the main thing that I noticed with the bar change physically (other than the fact that in a hairpin on an autocross course the stiffer front bar took a full car width off of the radius of the turn!!!) is that the front of the car stayed MUCH flatter. As a result, I *believe* that the stiffer front bar became effective by planting the outside front tire more firmly and keeping a better contact patch on the pavement with the inside tire. I know that the bigger front bar doesn't go with conventional chassis logic, but has been successfully used for many years in stock class where only the front bar can be played with. We may be overcorrecting until it starts working, but the point (for me) is that it *does* start to work, and work well. I think it is also worth stating that, on stock springs, if you've lowered AT ALL within the stock class tolerances, with sticky tires you could run the risk of bottoming out the shocks in a hard turn. It may be that stiffening the front keeps the outside front off of the bump stop, thus allowing the suspension to work (radical concept, huh?). In the end, I have a few theories, but all I really know is I'm faster with the front stiffened.

Now, BIG caveat - I'm a motor guy, but I've worked with some VERY smart chassis guys who have found front grip going either direction. YMMV, though most I've seen on the forum and at the track have stiffened the front with good results.

On the shocks, however, be aware - I tried running the front shocks at FULL stiff and got remarkable turn-in. I also got braking that was SO touchy (shock loading the front tires straight into the ABS on pedal tip-in) that I had to be either VERY smooth, or soften the front shocks just a bit to provide some forgiveness.

talon95

Well that's the downside to the Pfadt shocks IIRC. They adjust compression and rebound at the same time.

Dave G.

Racin Time

The car was stock.

C6DuffMan

Subscribed to thread. I'm also campaigning my 09 Z in SS, albeit on street tires for now. I have Pfadt SS front bar in the middle setting and I'm about to adjust it to full stiff. As mentioned before, keeping the Z flatter in the corners seems to help. I've have pictures of my Z on the course and I'm amazed at how much it leans.

poser

i run the 315s in the front, and it greatly helps turn in and in reducing understeer...i have my front bar (pfadt SS) one hole away from full stiff, and my front shocks 14/16 and rears at 12/16...zero toe up front (wish i did toe out), and 1/16" toe in at the rear...camber is 2.3, the most mine could go and be even left to right...

i run the hoosiers at 43f and 39 rear...i just followed the hoosier recommendation for pressure...anyone else running them this high??? i get to right about the end of the tread and onto the sidewall with these pressures...

no rolling onto the sidewall for those of you using lower pressures?


looks like i'll try to go full stiff on the front bar for the next event...

anyone have a good auto-x brake pad recommendation??? still on the stock pads for me, but i'm gonna change that soon...car is driven to the event about 20min away, but doesnt see much use other than a auto-x car, so life/longevity no a big concern...

any help appreciated guys...thank you...

Racin Time

Did you remove any of the washers on the upper control arms to get more camber?

This is from Hoosiers web site regarding tire pressures.

http://pinhoosiertire.blob.core.wind...s/tctR6_A6.pdf

CorvetteZ51Racer

I autocross at -2.3 Camber in the front and -1.8 in the rear, same toe as you, but 295s in front, not 315s. For brake pads, the only non-stock pads I've tried are Cobalt CSRs. They work great for autocross, but dust like nothing I've ever used on any other car. 3 days of street driving and my wheels are almost black.

poser

i'm not sure if my alignment guy removed any washers or not...i have to check next time...if not, i'll see if i can gain a bit more by removing some...

for some reason, i remember 43 as a hot pressure for cars over 3000lbs...i guess i was wrong...i'll try the lower pressures at the next race...

good to know...i'm not too concerned about brake dust, just initial bite/stopping power...i'm leaning towards the carbotechs right now, but not sure of which compound to go to...a friend of mine also had rb 500 pads on his mitsu evo, and i was very impressed with those...

thanks for the input guys, i really appreciate it...