Just put new PS2 N2s on 7GT3, 235/35/19 and 305/30/19

Alignment specs before w/ 235 and 295 was...
Camber -1.3 / -1.75 (Left F/R), -1.5 / -1.75 (Right F/R)
Toe .09" in / .12" in (Left F/R), .09" in / .12" in (Right F/R)
Caster + 8.5 (Left F), +8.5 (Right F)
Swaybars Front - full soft 5th hole
Rear - full stiff, 3rd hole

Alignment specs after w/ 235 and 305 is...
Camber - 1.0 / -1.75 (Left F/R), -1.0 / -1.75 (Right F/R)
Toe . 03" in / .06" in (Left F/R), .03" in / .06" in (Right F/R)
Caster +8.5 (Left F), +8.5 (Right R)
Swaybars Front - full soft 5th hole
Rear - med, middle hole

With the settings before and 295 on the rear, the car would rotate pretty good and had a good bounce, but with what the shop called a good street setup on the new 235/305s, this thing is like a piece of sh@#!t...

I am pushing going in and wiggly coming out in low to mid speed corners around 4~70mph !!!

Any suggestions on setups?!

Thanks

 

For a quick change, you can add the stiffness back in your rear sway bar. That should help some. If it's not enough you'll need more negative camber in the front as well. Also 0 toe or toe out in the front helps with turn in as well.

What do you mean by wiggly coming out of turns?

 

speaking of camber, everyone decides for himself, but there is a sort of rule of thimb to keep camber within .5 from front to rear.
more camber you get - more stable you`ll be in the turns.

i personally prefer to have more camber in front than in rear. for street tires you should be very good on something like -2.5 front, -2.2 rear.
keep front toe to 0 or to 0.02 and rear toe to 0.10.

305 rear tires do want 245 tires in front, as combinations of 235/295 and 245/305 have correct outside tire diameter ratio.

 

The turn-in is not as sharp or quick and the rear just doesn't feel solid and follow through, especially if you have change in elevation or uneven pavement. If that makes sense.

I have the rear sway back on stiff now, and its a bit better, but it seems to show that a fraction of degrees is a lot in these suspensions.

 

Agree with rear sway bar suggestion. Remember, however, that all new street tires will feel "wiggly" for the first two to four hundred miles. Tread squirm and just getting rid of the lubricant they use in the manufacturing process. I'd give them a little time and if you still don't like the setup, then re-do to more aggressive specs.

 

Yup, at first I thought it was the new tire feel as well. I used this 7GT3 as a DD for a few days and its been through 6~700 miles already.

Porsche recommended alignment specs are...
Street Use:
Camber -1.4 / -2 (Left F/R), -1.4 / -2 (Right F/R)
Toe +6' / +13' (Left F/R), +6' / +13' (Right F/R)
Caster + 8.5 (Left F), +8.5 (Right F)
Not sure about swaybars though...

Race Use:
Camber -2 / -2.5 (Left F/R), -2 / -2.5 (Right F/R)
Toe +0' / +16' (Left F/R), +0' / +16' (Right F/R)
Caster + 8.5 (Left F), +8.5 (Right F)

 

You/they added rear rubber then adj sways and camber to reduce front grip. Certainly a recipe to induce understeer. As OP noted, tightening rear bar will help, but getting -2 or -2.5 camber in front will really help.

You know hot tire pressures are critical to check, yes? Big affect on handling/balance.

If you do not yet know how different changes affect handling, best to Google for one of the various set-up charts floating around.

Good luck and congrats on being brave enough to decide to experiment with settings. Many folks are scared to even try.

 

Thanks. Its amazine how a fraction of a degree in camber and a scant 10mm in rear tires can make the 7GT3 lose its wonderful sharpness.

I think the next set to try is to bump the "shop recommended" camber for front from -1.0 to -1.7 and -2.0 at rear on Monday.

Does anyone have notes that they'd like to share on incremental changes and how they will affect this car? With each 0.5 change in camber? And any suggestion on toe for front and rear? The pressures are at 35/38 cold and around 39/41~ish warm.

 

All else being equal, if you increase negative camber front and rear you will gain grip overall and preserve the understeer! Think about this.

If you stay with the same tire sizing, and you are out of anti-sway bar adjustment (you are now), then camber is your next best method to dial out the push. You would need to increase front camber and keep rear camber the same or even reduce it if you want to reduce the understeer.

Oh- and most DOT track tires, like low hot pressures: MPSC/Pirelli Corsa System/Pirelli Trofeo hot front approx 31-33 psi, rear 34-36 psi.

Your assignment this weekend is to Google suspension set-up before you go any further. Class dismissed

 

Nothing like going back to school on things you want ... don't forget to take a bite of that apple...

 

Why did you have 295's on the rear in the first place? The proper size on the 7GT3 is 305. First thing I would do is get take the PS2's off! I tried a set on my 7GT3 and took them off after 1500 miles!! Not a good tire for the GT3.