mryaknow

I've been struggling trying to get my '04 Z06 to rotate at corner entry. I've been running V710s, 275 front and 315 rears for about a year now. In the other cars I've autocrossed my corner entry rotation has been controlled by how I release the brakes. With the Z06 no matter how I release the brakes the car doesn't want to rotate. I'm thinking about running different rear pads hoping that it will move the brake bias towards the rear just enough to get some controllable entry rotation when desired.

I was thinking about using the OEMs on front and some Hawk HPS Plus in the rear.

Has anyone tried this? Any suggestions on other combinations of front and rear brake pads for Autocross use?

Any help would be appreciated. Thanks.

VetteDrmr

Many folks play around with different pads, but IMO if you're running 275/315s you're not going to have much success trailbraking a C5 regardless of your pad selection.

The ABS will keep you from sliding the rear wheels, and when I've tried it autocrossing I just end up going too slow into the corner.

One way to get the car to rotate better is to go to a square setup: in your case running 315s all around. Then you'll have enough grip up front to get the rears to loosen up.

HTH, and have a good one,
Mike

mryaknow

Thanks for the response, Mike.

I was afraid with the 275fr/315rr that might be the case. I guess the 315s are like an anchor?

Going 315fr/315rr would be a good suggestion, but I would like to stay in SS so I need to stick with the stock wheel sizes.

Thanks again.

ltborg

most guys ive talked to run the v710 in a 295 on the stock rim. when ive seen them in person they look like they fit fine. 275 is definitely not enough tire for that car. hope that helps.

Jason

295's fit fine on a Z06 front wheel.

TedDBere

There are several ways to increase rotation at corner entry in addition to adding rear brake bias with pad choice. But adding rear brake bias is usually done if you are consistantly ABS'ing the fronts on entry and you want to add additional stopping power without kicking the front ABS on, IMHO.

Things you can do to increase rotation on corner entry:

1) Increase your rake

2) decrease front bump

3) decrease rear rebound

All of these will aid in corner entry rotation by allowing faster weight tranfer to the front upon braking thereby loosening the rear.

4) Add +0.25 inches to each of your front wheel offsets and leave the rears stock.

Your formula for success is up to your driving style and your car's current configuration.

BTW, I'd start by getting rid of the kumhos and putting on 295/315 A6 Hoosiers, FWIW.

Solofast

Ted is right, the Hoosiers turn in a lot better and you can get whatever turn in you want with this car with shock tuning.

Also you need some toe out in the front to get these cars to turn in, you didn't mention if you had tried that yet or not...

I used the 295 Kumho's up and they were fine, others used the 275's and were just as fast. The 295 Kumho's were more "rubbery" and the car didn't turn in any better with them, The incresed sidewall flex of the bigger tire didn't help turn in at all. You can always account for some phase lag with driver anticipation, but I am not thinking that it is the 275's that are making the car not turn in, it is something else.

VetteDrmr

Sorry, I assumed you were running 17" wheels.

Mike

XPC5R

I think it's acutally increase rear rebound settings. Also adding a little bit (1/8-1/4") of rake will help turn in as well.

The pad change will help, bet be ready for differing heatup/rampup rates. The car may not rotate much when cold as the racier rear pads have not come up to temp.

ZR1 MK

I use my Wilwood Q street pads at the front and PF 01 track pads at the rear for autocross only. Contrary to popular belief, the cold 01 pads out perform the street pads. It works, but dont forget and leave this for the track. Did this once and got some wild results before I realized. I dont run ABS.

mryaknow

Great thanks for all the input. It is very helpful. I will try, as many of you suggested, to increase rake slightly. I am running the 275s in the front because I understood the trade off between the 295s and the 275s was steering response (275s) vs steady state grip (295s). I thought if you looking for entry speed the response would be more critical. I'm not sure about this though.


Solofast

If my memory is correct I am running zero toe front with -1.9 degress camber and 1/4" toe in rear with -1.4 degrees camber.

Also one more questions about increasing rake. How will this effect the mid corner and putting down power exiting at various speeds?

Thanks for all the informative responses. This forum is a great source of information.

TedDBere

You could also adjust the rear tire pressure too, BTW.

Solofast

You are right in the tradeoffs between the 275's and 295's, response vs grip is your choice.

You need at least 1/8 of an inch of total toe out on the track. Mark your tie rods with a paint mark so you can reset them and try some different toe settings. 1/2 a turn per side = about 1/8 of an inch of total toe. You may try more, up to the limit of some loss of front end grip...

What I came up with was 1/2 a turn of toe out (per side from zero) for the track, and a half a turn of toe in per side on the street. That helps the tire wear and minimizes the tramlining on the street...

mryaknow

Thanks for all your help. I really appreciate it.

Now if I could just fix the driver, I'd be in good shape.

Take care.

rustyguns

i do same