Quote:
Originally Posted by petevb
Thanks for the clarification.
I'd always been under the impression that the 993's rear suspension was designed to create more camber gain than earlier cars. If I'm reading this correctly, however, the 993 actually gains less camber than the 964 for a given deflection. I've never seen this type of graph for a 911, but I believe the rear camber gain is near identical to the 964. Hmmm...
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The big difference I notice between the 993 and 964 looks like the toe at the rear- the 964 tries to maintain a relatively consistent toe (in), while the 993 toes in on compression but toes out when it unloads. I understand this is to create a 4 wheel steering effect in cornering (the rear turns into the corner), but it would seem to create instability under braking, when the rear would toe out. But the 993 has a collapsible link that comes into play under braking and corrects for this? Thus the theory is that recreating the 993's camber and toe curve on an earlier car wouldn't help unless it also had a collapsing link?
Very interesting stuff... [/QUOTE]
Both 993 and 964 use a a derivative of the Weissach axle first introduced on 928. The 993 has a 5 link design where 4 links are solid and 1, the kinematic toe, is elastic. On the 964 W/ this type of axle, under cornering the outer wheel assumes a toe in and the inner assumes a toe out attitude reducing the slip angles that the tire runs at and thus increasing cornerning potential. This is the opposite of what a solidly fixed suspension does.
In the front they both also use differentially elastic bushes to help eliminate bump kickback.
The whole point of most any suspension is usually to minimise camber and track variations. The best at doing that is unequal length A arms ala 959, struts are among the worst.
964 rear achieves the Weissach effect from differentially elastic bushings in the back as well as the front. But even w/ this design camber and toe variations are interdependant
