Well 93 FD...

JIC FLT-A2s
Yokohama AVS AV145is 245/50/16ZR
JIC Front strut bar
Stock Rear Strut bar
Stock Swaybars.

Wondering if anyone has tire pressure they like or what stiffness they like on their suspension...? Tried a couple different things out there this past Sunday but seems like softer i can get the front the better...

Anyone?

 

I have always found the opposite no matter what suspension mods to the FD: Stiffer shocks, stiffer springs, stiffer sway bar and more tire pressure in the front compared to the rear gives better turn in and better exit.

 

so i should loosen up the front, put the fronts stiff and run about 35-40psi up front? It was really pushing hard thru a turn...

 

er loosen the rear, stiffen the front?

 

this is my setup for autocross:

JIC FLTA2
Stock swaybar front and back.
17x10 CCW with 275 A3S03 or 16x7.5 225 Kumho MX

Front:
Front shock is about 14 out of 16 settings
Tire pressure 37-40psi depending on surface.
-2.7 camber
1/16th toe in total (I think this should be out on the next alignment)

Rear
Rear shock is about 6-8 out of 16 settings
Rear tire pressure is about 33-35psi, depending on surface.
-2.2 camber
1/16th toe in total.

On uneven surface, lower rear shock setting and tire pressure is good. On airport tarmac surface, higher pressure is better so is higher setting.
The numbers given above in ranges are rough surface to smooth surface...or hot to cold tire temps.

 

reza, you sure you have that much camber? You can only get about 2* negative without slotting something.

 

the 2.7 is basically maxed of camber adjustment, I was aiming for 3, but I need to lower the car, which I don't want to do.
My mechanic said, the car is not lowered enough to get to 3, I saw other FD with GAB SuperR and Ground Control able to get to 3*

 

To get anywhere close to 3* I would think you'd have to slam the car nearly to the ground. Most I can recall an FD having is 2.5*

 

i'm running -2.7 in front now too. there was more there to get too. at least -3.0 is possible. maybe next time

reza, what wheels did you have on during the alignment???

 

I have the Kumho MX 16x7.5 225/50/16
With wider wheel, I should have more camber.

I think from the tire wear at last event, it shows that the camber may still not be enough...

 

well i'm running -1 camber in the front and stock toe and caster. front rear.

so stiffen the front and up the pressure... drop the rear pressure and loosen the rear. we autox always on an airfield.

 

here i am autox...

the front is tires tuck just a tad and the rear is a little lower than stock.. its not slammed by any means.. just a nice agressive stance.

 

Actually a wider wheel (and therefore lower profile tire) will not need as much negative camber since the tire sidewall is stiffer.

 

Damon, I don't think that is the right reason for having less or more negative camber.
The faster you go thru turns, the more camber you want to have. Of course this grows with experience. The faster of a driver you are and the more camber you want.
Plus the tire will show you if you have enough or not.

Reza

 

reza that's all true but even so we're talking relative here: A lower profile tire will not need as much negative camber as a higher profile tire.

The reason you add negative camber in the first place is because during cornering the contact patch loads up and the sidewalls in effect try to fall over. The negative camber ensures that when the sidewalls do fall over the contact patch is flat on the ground. A lower profile tire has less sidewall flex and thus does not require as much negative camber. The reason lower profile tires were invented is because they distort less at the expense of a harsher ride and decreased load rating.

You only want enough negative camber to make the entire contact patch work during cornering. Any more than that and you're overly wearing the tire along with giving up straight line brake and acceleration grip.

...as for speed that really doesn't count; body roll and tire loading do. More body roll will require more static negative camber.

 

it is all really do to the tire's slip angle, but unless u can get tire data or figure it by testing different slip angles and camber angles to find the greatest tire force generated the only way to to guess and check using a pyro gauge across the tire.

Too much camber and the slip angle goes to ****, too little and u are not getting the max forces the tires can generate.