Palmrwnd, I've noticed you going urethane throughout. Could you tell me which ones you used on your car? Thanks a bunch.

BTW, if you see that the paint is worn off of the bar where the bushings contact it, take the bar off and refinish it properlyand completely. If you don't, you will get noise no matter how often you grease the bushings, even with graphite.

I have just finished adding the 20mm rear bar and 28mm front from my dead active Q to my "new" 90, with poly bushings and tightened endlinks. Like a different car. The old bushings were so worn the 29mm front bar couldn't have been doing much.

The driverside of each bar will bend [transmit force to passenger side] trying to right the car, but the bushings will just deflect as there is slop until they are totally compressed.

Rememember the bar link point at the arm only moves 1/4 or roughly +-1.0" and whatever compression is in the bushing might be 1/2" so the bar inself may only move 1/4=1/3" so 0.05" is a significant 15-20%.

Can you feel the rear rotate in corners now?
Unfortunately once you start improvements you want to continue on to perfect! And it immediately show you how bad your rear tires are. Currently running SZ50 [with 16k on them] on the rear and AVS I [with 3k] on the front speaking of mix and match, doubt you can find a stickier group in 15" currently.....but I'll have fun till Nov/Dec when the temp turns cold enough to switch back to the 235/60/15 Michelin Pilots

I am assumming you drive by yourself most of the time when you get frisky.

As we know the spring rate but not the added spring rate of the nitrogen in the shock [pushes up wards just a little] plus the spring may be a little non linear in captivity], plus the rubber strut tower doughnut, then the offset from the tires center, plus the exact stiffness of a 28 mm bar mounted in rubber with the bushing end links.

My calculations are good but still prone to errors that creap in and at best I am only 90% correct whereas a race car is know to the pound not 30 pounds [or more] of potential error as I might be off on the front in roll stiffness per inch......120 pounds is significant in a 4" body roll you might be compressed against the bump stops in just trying to get another 0.02G out of our behomoths. As the max for the tire is 1521 so 120 pound variance is almost 8% which could translate into a 5- 8-11% variance in the possible G force ability of the front tire which is the limiting factor in the slalom.
Why I like 1640 tires [on the front] they can handle my possible errors better with their added weight carrying capacity.

There is a method to my madness!

See if your front end bar link bushings are worn even 1/4" [1/8" on each of the two x both sides the front bar loses most effect for the first 2" of body roll so the total front stiffness is reduced by 300+ pounds allowing the body to roll an 1" more than we portray.

Just wait you'll get to the point where as you tighten the rear the front moves more, as you tighten the front the rear moves more....finding the Goldilocks adjustment is a constantly changing battle......quarter of a turn on a nut [compressing bushings] get noticeable. And they change with bushing, tire, and shock temperature............tire pressure variances of 3 psi begin to be noticable.......they say a Nascar driver can feel 1 psi change!

It would be cool to know that 25psi=so much roll stiffness

Hey Fred, email me about the accumulators [email]mpeters@houston.rr.com[/email]

Thanks

Marvin

It feels more neutral to me now. My description of neutral may be colored by the fact that our other cars are a 911 and a 66 Corvair (really!), so a litttle rear bias is not unusual for me. Actually though, the level of adhesion in the Porsche is so high that it is hard to get the rear to move out, except in a trailing throttle situation.