NLowell

I hope I dont' get flamed for searching....I searched for 2 days and couldn't find what I was looking for.

I have a 05/f55/mn6 Coupe that I need to be stickier! 3rd year autocrossing, end of the first year with this car. I know I need some driver enhancements but I also need to stick my tires better.

Questions:
1.) Will Z51/Z06 sway bars screw up my F55?
2.) Will slightly lowering and adding some neg. camber screw up my F55?
3.) What Tires/Rims are suggested for Autocrossing? I tried the Pirelli PZero Corsa's and hated them. Went back to stock and they seem much stickier (and more predictable) I need some beefy rears but I can't find a 18x11 that would fit...

Thanks in advance for any hlep

acrace

While I haven't set up a F55 car for autocrossing, I do have a little familiarity with the system.

Bars, slight lowering, and a more aggressive autocross alignment won't affect the F55 system.

While the F55 system is awesome for street driving, you may want to consider swapping the shocks for something more autocross worthy. That depends upon your priorities.

I don't have much experience with street tires for autocrossing (sounds like, based on your Pirelli selection, that you're looking for a dual purpose tire), but some of the fast guys around here are on BFG K/Ds or Michelin Cups.

Solofast

Depends on what class you want to run and how serious you want to be...

It looks to me that you haven't really gotten all that you can get out of your basic setup. A serious alignment, lowering the car some (not slamming it all the way down) and corner weighting of the car will make a big improvement in performance for little cost. Going to different bars (at least in the rear in SCCA) will, take you out of stock class and just compound the problem since you will now be running against seriously prepared cars that are taking full advantage of all the prep allowances. You will go faster and have more fun driving, but you will get seriously beaten when a car prepped to the limits of the rules shows up.

After alignment, lowering and corner weighting you can improve to a serious set of tires. At that point you can decide if you want to go the mod route or stay in a stock class.

It all depends on how serious you want to be and what level of competition there is in your local area. Look at the rules for where you are running first, before you start changing anything and then decide on what to do, based on who is running in what class and what level of prep is there. That way you can have fun, not spend a ton of money, and then be frustrated that you are in the wrong class because you changed something that didn't get you much performance, but bumped you up to a higher level of prep.

NLowell

Thanks for the replies!

To clarify, I go autocrossing about once a month but for on and off periods. My priority is to keep the car very street worthy but capable on the track. I tried to go dual purpose with the pirellis but now I am considering dedicated rims/tires for autocross.

As far a class goes, most of the time I run out of class. I have a good friend with a new M3 who is an old time porsche race driver who has serious driving skills! I go with another friend who has a pristine factory 5 cobra with stickies who hauls butt! Right now I'm about a 1.3 seconds behind them and I need to catch up

Driving skills is a slow progression but I'm working on it. Sounds like I need the bars and some setup work first. I read on another post that according to calculations, adding the front and read z51/z06 bars is much more of a thickness increase in the rear introducing (according to calculations) much more overstear. Does anyone have this setup that can attest? (F55 w/ z51/z06 sway bars)

Thanks again!

P.S. Ordered Z51 sway bars this morning from Gene. I was afraid the Z06 rear sway would introduce too much overstear.

bgenerous

I just finished my first full season of auto-x and I can tell you that the biggest change you can make to help your times (other than seat time) is dedicated racing tires. My times dropped by over 2 seconds the first time I ran with racing slicks. I just went through my first set of Hoosier A6's and got over 92 runs on the front tires before I hit the cords and that was with a street alignment and not flipping (will be doing that next year).

I use my original Z06 wheels for racing because they are strong and light and run after-market for daily driving.

Just my 2-cents.

GTB/ZR-1

You did it the right way--learning how to drive on streeties.

I'd start w/ tires & an alignment & go from there...

TedDBere

I run the F55 with Z06 front bar, but on a C5. It looks like yours is a C6.

Here's a comparison of bars...Stock on top, Z51 in middle, Z06 on bottom:



You can lower on stock bolts.

Good luck.

NLowell

Thanks everyone. So I am lowering, corner balancing, aligning with some negative camber and installing the z51 sway bars.

Final question is Rims and Tires.

What solutions have the C6 guys found for autocrossing?

There is only one 19" tire and it comes in 315 which means I would need an 11" rim.

I could go 18" tire and rim but no one makes a wide 18" rim, but I'm afraid that will mess up my geometry.

Thoughts? What has been done?

C6400hp

CCW Corsairs. I run their 18X10 up front with a toyo RA1 275/35/18 and and 18X11 in back with a 305/35/18. If you change the wheels to a wider size like I have with the CCW you will no longer be in the stock class you will run in ASP.

aggie88

Not at all - but be sure you make the corresponding adjustments to tire widths to compensate for the stiffer end to maintain neutral steer.

Won't affect the F55 but if you drive a lot on the street, don't get too aggressive with the camber setting. Which brings me to the next question...

I recommend the Kumho V710s. They require less neg camber than the Hoosiers. I was running on Nitto Extreme IIRs for about a year on my 05 and just put on the 710s. 285 30 and 315 35 18s on 18X10s and 18X11s that were fitted on a C5 Z. My times are on now on par with the stock Zs on sticky tires. The rears do sit kinda far out - but these are for autox only. I also have a "mild" amount of neg camber - I think about 1 1/4 in front and 1 in rear. so that helps a bit to keep the top of the rears in line with the fenders.

NLowell

You mean that you have C5 Z06 wheels on the rear of your 2005 C6? That is a huge difference in offset isn't it?

Do you have any pics with the autocross wheels on it?

You are correct, I dont' care too much about looks or sticking out...I just want sticky!

C6400hp

C5Z06 wheels are 17X9.5 and 18X10.5 and the offsets are wrong for a C6.

tjZ06

Are you concerned with classing at all? Assuming not then 17x11 "ZR1" style rims with Grand Sport offset work great on a C6. I have them with 315/35-17 Kuhmo 710s and 335/35-17 Kuhmo 710s front/rear for my 'C5 Z06 but when my car was down I used them on a buddy's base-model C6 and they worked and fit great (they will stick out ~.5" though). The C6 I used my wheels on was also upgraded to C6 Z06 shocks and sway bars (with stock "base" springs) and it worked very well while still being smooth on the street. It was a great setup for a daily driven fun car.

-TJ

NLowell

Ohh, very interested in those. Anyone know where I can find a set?

Thanks for the info!

aggie88

Here is one. Please click on "My Corvette Photos" under my avatar for more.