Bill Verburg

I'm looking for opinions and info as to what might be the best ride height and alignment specs for a mostly tracked 993.

Front end will have RS/EVO uprights, JIC shocks al laround, RS sways, 8 & 10 x18 MPSC. Considering urethane bushings in front. The rest is mostly stock for now.

Feedback i've recieved so far
"It's too low" it certainly is a pain on any transition to a different plane

FLA997

Bill-

We've spoken briefly about your ride height before, and I am still bewildered as to how you got your JIC's that low. Mine are within a thread-turn of being bottomed out, and is noticably higher (esp. in the rear) than yours. While I don't know the exact mm height from the factory points to the ground, I'm happy with my height.

Bill Verburg

The concern of course is bump steer, roll couple and camber patterns.

The feedback I've gotten from knowledgeable sources is " too low" ," the roll center goes under ground" but no further explanation. I understand that the roll center goes down faster than the CG thus increasing the roll couple but no explanation of where or how to optimise ride height. Obviously some place between RSCS and mine(which is supposed to be around Cup height). In addition it seems that there are several different approaches to caster and toe. More of the former and less of the latter seems to be more common.

FLA997

I was just about to comment that I think your car is Cup Height~. Let me see if I can find my alignment specs indicating toe. I know I'm running some serious camber (-3.4front, -3.0rear).

Mark in Baltimore may some input.

ninjabones

I've got the JICs, RS sways and I'm almost exactly at RS ride height. Even with the TRG longer drop link mounts (thanks for the suggestion Bill... that saved me a lot of fabrication time from my mechanic), my rear sways look like they're going to rub if I move to the next setting (full soft now). What can I do to get more clearance here if I need to adjust the rear sway bar?

Bill Verburg

Dunno here's mine

John H

Here's my old car. It has the JIC's, TRG sways and drop links and poly bushings everywhere. It is sitting on 17's although I am sure the tire wall makes the circumference about the same.

George A

Bill,

Here is a pic of my car. It's below RS height but not quite cup. I think its too low. I've experimented a bunch with ride height and have come up with some theories. I'm by no means an expert at this, hell I'm not sure I fully understand it myself. I've realized that if my car is too low, it becomes a handful at the limit. Yes, I know the kin toe adjustment has to be just right.

I'm going to raise it to where the lower control arms are parallel to the ground (90 degree angel). Right now they are (I'm trying to figure out a way to say it), well ok, the connection point of the submember is lower than the wheel carrier. The suspension looks like it's in a compressed state (if that makes sense)...

Just as point of reference, I do not have the EVO hubs up front (illegal in class from what I understand). I do have the solid rear carriage mounts. I hear there is a tilt package for the carriage that improves the kin toe effect, but do not have it either.

George

Bill Verburg

George thanks, front A arms parallel to the ground is what I'm hearing too. I'm going to let the shop set it up the way they set up their own cars(mostly 964RS & Cup), I just want to understand what the compromises are.

From the little I know the height of the instantaneous center and the length of the roll couple are important, just seems to me that even if the roll couple is longer, which increses the roll tendancy of the car, stiffer springs wil negate that effect so there is a net benefit from lower CG.

I've looked at the oem camber patterns that Porsche published way back when and the GT2EVO patterns as well but it's still greek to me.

George A

Bill, I run 1700~1800 lbs spring and I think that's my saving grace. I believe any movement in my suspension significantly changes the geometry. BTW, I was referring to the rear bottom control arm. I can't do anything on my front since I can't use the Evo uprights.

George