RE: Z coupe rear suspension

["KOHLBRENNER,MICHAEL (A-hsgAndover,ex1)" <michael_kohlbrenner@xxxxxxxxxx>]

From: "G. Steinke" <g_steinke@domain.elided>

> Does the Z coupe (not the Z8, but the shoebox-looking 2 seater)
> have the rear suspension based on the E30? I remember reading that
> the Z3 convertible does, but that could be a mistake. I checked the
> BMW web site, and it said that the Z coupe has "semi-trailing arm"
> rear suspension, which I think is what the E30 had. The E46 has
> "multi-link" rear suspension.

BMW introduced the multi-link rear suspension in the 3-series in the
E36 generation.  When they introduced the Z3 roadster, there was
supposedly some space concerns, and they went with the semi-trailing
arm design from the E30.  They've used the same basic design in most
models all along.  The coupe was then based upon the roadster.

> In regular driving, does it make much of a difference?

I haven't driven any of these cars (E30/E36/Z3...), so I can't offer
my own personal experience, but from a theoretical perspective, the
semi-trailing arm design is a simple independent suspension design
that trades off ideal suspension geometry for space and cost.  Camber
and toe changes as the suspension moves up and down are not quite as
well-controlled as they are in a proper multi-link design.  When the
E36 was released, it owed much of its handling improvement over the
E30 models to the improved rear suspension design.

With all of that said, the Z3 (Roadster/Coupe) is intended to be
a bit more of a raw sportscar.  Reviews of these cars when they came
out specifically addressed the rear suspension design and most
reviewers didn't mind much since it was so much fun hanging the rear
out powering out of corners.  The multi-link would have improved rear
grip and precision slightly, but its absence didn't effect the smiles
per mile measure.

Best regards,
Mike Kohlbrenner

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