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panzerfaust panzerfaust is offline
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Join Date: Jan 2012
Posts: 900
Originally Posted by chrismorse View Post
This is a bit nieve, I know, given the infinite variable combinations and range of desired results.
If we aim for a "more sporting street useage" mid year chassis set up, that is starting from stock height/alignment how much can we lower the front/rear without adversely impacting linear high g cornering?
I. Do not want ultimate grip, at the cost of twitchy, sensitive,narrow range balance.
The good Dr. Verberg once opined that the front could be lowered a bit, reducing the roll moment. But what about the rear roll moment.
I am Not at all clear about how the front/rear roll couple affects predictable, linear response. Clearly, camber curves and toe steer complicate the quest for linear response.
Am I. Correct in assuming that we don't want any "self correcting" suspension dynamics??

Still a little uncertain 😳
probably a tad lower than euro spec. stock ride height the 911 strut suspension already exhibits more bumpsteer than a double a arm agreements. lowering it much beyond stock creates massive bump steer especially noticeably since there isnt a power steering to damping the steering kickback in your hands. on the rear you will loose some anit squat tendency in which the 930's have in raising the pick up points i reckon.

im not sure what Dr. Verberg meant but if you lower the front excessively your rollcenter goes subterranean in effect it making your suspension softer due to larger roll moment from the cg to the rc. your camber camber curve would be reduced even more....early 911 had very little to begin with. this is the reason folks use raised spindles so you dont alter the rc much while u lower it. still you will have bumpsteer twichiness to deal with separately with raised spindles.

roll coupling is the side axis of the two axles. nearly all road cars engineers this for the front to loose traction first for safety reasons. rear rc are typically much higher than fronts... at times 2, 3 or even 4x higher. i dont know the roll coupling of 911's, its a strange and interesting platform. :-) anyone have mech drawing of this?

you absolutely can benefit from "self correction suspension dynamics" which is what most modern complicated 5 link suspension are. they tailor the toe through the jounce and rebound travel for the desire effect. i believe the 993 rear end has some attributes of it. the 928 also did with deflecting suspension bushings in creating toe vs toe out of the semi trailing arm under braking to tame the rear end.

for practical purposes there are enough worms out of the can, so dont tread there with "dynamic suspension" and lose the unique quirky feel that many of use love. anyone here besides me prefer the feel of the 964 over the 993 besides me?

my 2 cents
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