RE: Wandering, Negative Steering Roll Radius?

[JustaxPHX@aol.com]

>Audi published a Sales Training book called the "1991 Engineering Fact
>Book, Audi 100/200 Series" . This book has a few new tidbits of information
>and discusses the Negative Steering Roll Radius Geometry design used in the
>steering/suspension system.

Audi's "Negative Steering Roll Radius" is a fancy term for the more frequently
used "scrub radius."  On the 4000-based cars, it varies between 12-14mm -- the
exact number depends upon where the balljoint is positioned) -- which means if
you increase the offset of the wheel by more than that -- say, changing from a
45mm offset to 24mm -- you now have a positive scrub radius and all of the
benefits that Audi claimed from the design are gone.  This is another reason
why I'm so puzzled the lack of any significant changes in the Ur-Q's
suspension when Audi changed from 6x15s to 8x15s but I guess that's another
thread...

I've never bothered to actually measure this on a Type 44 car but I seem to
recall reading somewhere that it's nominally the same 14mm as on the
4000-based cars ... guess I'll need to put measuring this on my list of
projects.   :^)

JG