Interesting discussion regarding various vehicle models/designs,
dampers, etc., but, IMHO, the original premise of this debate is
incorrect:
> FWIW the likely cause of the E30's propensity to roll
> is the semi-trailing-arm layout of the rear
> suspension. The roll center of such a design is very
> high compared to a strut or double A-arm design, which
> means that cornering forces tend to lift the body,
> which raises the roll center, which lifts the body
> more, and so on until the center of gravity moves
It is true that a high roll center may create a propensity for roll
jacking, but semi-trailing arm suspensions do *not* have a high roll
center. With a trailing or semi-trailing arm arrangement, the
designer can place the roll center anywhere between ground level and
the elevation of the arm pivots, depending on the angle of the arms
relative to the axle.
Perhaps not quite as good as double control arms, but semi-trailing
designs work reasonably well, as evidenced by all those Porsches, BMWs
and Mercedes this thread has been referring to.
> outside the tire contact patch and the car rolls.
> Same thing that happened with swing-axle Corvairs and
> Spitfires, only not quite as sudden.
> The same suspension, and same problem, is shared by 318Ti's and
> Z3's
*Swing axles* are NOT semi-trailing arm. Yes, orginal Beetles and
Corvairs has serious roll jacking. These were swing axle designs.
Time to dig out the Fred Puhn and Carroll Smith works and brush up....
Regards,
Roland
ESP Merkur XR4Ti with a semi-trailing arm and roll center 1" above
grade.
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