We're trying to develop a better set-up for my friends 997 GT3. It's surprisingly pushy in steady state and also likes to sway ends under a variety of conditions. Trail braking with it just causes massive corner entry understeer. Oem Corsa tires. Shocks kept soft. More understeer when the Stiff setting was used. Traction Control Off. Exhaust opened.

We were very surprised to find the oem sway bar settings to be full stiff in the rear and almost full soft in the front. (I believe the opposite of the 996 GT3 oem settings) We tried to soften the rear bar, but found that we could not pull the upper endlink bolt out far enough because the shock was in the way. We couldn't undo the bottom endlink bolt ... which might have given us more room because we needed an especially short Torx driver to hold the bottom bolt in place while we loosened the nut. (Are we missing something?)

The front bar is easy to adjust. We stiffened one side to full stiff ... but the understeer was not better. We tried different air pressures. Going lower did not help. Going back up to stock pressures helped.

Is it true that the oem Corsa tires are a big part of the problem? ... and that we should at least go to R888's?

We don't want to necessarily develop this car into a hardcore Nationally competitive SCCA ASP Solo racer, but we would like to make it more fun to drive hard on our typically fairly fast Southern CA auto cross courses. Right now we can't really "lean on it."

What we're looking for is a list of suggestions, in the most productive order.

1.) More Aggressive alignment: Front: -3.0 camber, 2mm total toe-out
Rear: -2.5 camber, 4mm total toe-in. The only setting I checked at the track was the rear toe ... which was around 2 to 3 mm total toe-in. I just wanted to make sure that the toe wasn't OUT.

... AND ... get that rear sway bar softened.

2.) Better R tires. Should my friend consider getting 18" CCW wheels, so he has a better selection of tires? I believe in 19" we might only have a choice between Hooser A6's and R888. Although those Toyo's might be OK in our up-coming Southern CA heat, typically they, like the oem Corsa's, take too long to heat up for Auto Crossing.

3.) More aggressive Sway Bars ... and I think the ones to get are probably the GMG ones.

4.) Stiffer 600/800 springs. I don't think we want to go there.


Please offer up your recommendations! thanks ...

What is the oem ride heights. Center of wheel to inside the fender lip. This car, bought new, was a special order that wasn't picked up. Does it look like it's been lowered?

 

Feel free to give us a call........... We have set up several fast Top Time of the Day cars..

Would be happy to help.

 

I've autocrossed my 6GT3 with good results so take heart. Generally I think the car responds to "less antiroll bar" for autocrossing. To reduce the understeer, you want to set the front bar to the softest (farthest out) position. When you put the bar to the stiffer position, you are actually going to make the understeer worse. Try just changing the bar in front (one change at a time!) and give it a try

 

You are going totally the wrong way.

Softer sway in front = more grip front
Harder sway in front = less grip front (more push)

Stiffer sway rear = more oversteer rear
Softer sway rear = more grip rear (usually creates even more push)

For Auto-X there is nothing to win with a very stiff suspension setup on a "big car" like a 911. An out of the box will make you go faster if you just dial in the balance.

Tires is the one single think that can change the above. The better tires, the harder you can make the car. As long as you stick to R-comp, stock chassis setting is good, just know what you are doing.

Your 2mm toe out will increase your push. It WILL make turn-in better, but after that inital response you will PUSH. Set to 0 for auto X unless you have serious turn-in issues (not very common on these cars).

Rear end toe in will also increase push. On a very aggressive track qualifying setup, you can go close to neutral in the rear, just to make the car turn faster, this is pretty usable for AutoX when speed are low and you need to rotate fast and get the rear end to come around easily.

Get the basics sorted out and save money doing the basics right first. R-comp tires are always a great improvement though and always worth it.

Good luck and have fun!

 

Thanks ... I wasn't sure that Gary Thomason fellow knew what he was talking about.

... "real" R tires transformed the car, ie. 19" Hoosier A6's and 18" Kumho 710's

 

Great to hear about the tire improvement. It is very common that not enough grippy tires creates a car where the chassis doesn't work. Heating tires for AutoX is always an issue on tire compounds for real track racing.

Very normal to see GT3 with full stiff setting on rear sway btw. It is done so by people who believe it make the rear more stable, which it in a sense does, but it also does it at the cost of actual grip. It drifts nicely with full stiff in rear though.

 

(Of course Gary T's word is gospel in my World :-)

 

Mako - if you're there this Saturday, I'll help out. Just give it to me for half the day and I'll take care of it.

 

What's this about flipping the SuperBee?!

Hi's going to be there on Sat ... just get in line. :-) ... have correct change in $20's and fives.