Re: 4th gen. quattro

[AUDIDUDI@delphi.com]

> Also note that a few enlightened manufacturers of high-performance FWD
> cars are starting to offer LSD's (sorry, can't remember who at the
> moment).

Nissan, for a start ... the Sentra SE-R and late, lamented NX-2000 (homely
but a kick to drive) both have viscous LSDs as does the Infiniti G20.  Not
the ideal solution for racing but it worked pretty well on the street...  

> With FWD, you can't use a clutch-type since it tends to jerk the wheel
> out of your hands (for racing only), but Gleason/Torsen types can work
> quite well in this application.

Actually, the problem with most clutch-type diffs is the fact they can't and
don't begin to work until one wheel has started to spin; the "jerk the wheel
out of your hands" phenomenon that's sometimes experienced with these in FWD
cars is generally the result of designing the suspension geometry around the
typical open diff and adding an LSD to the car at a later date.  As I'm sure
you recall, most early FWD cars had vicious torque-steer characteristics and
this was masked only by the fact they usually didn't have any torque ... add
a turbo to a first-generation Honda Civic, as a friend of mine once did, and
be prepared to change lanes whenever you get on (or off!) the throttle!

Modern FWD cars don't usually have this problem although they can if you put
enough power in them ... several years ago, I had an opportunity to drive an
experimental Chevy Beretta GTZ with almost 320hp (as compared to the factory
version that came with 190hp) and it would jump sideways 3' whenever you got
on the throttle.  With only 190hp, though, it tracked straight-as-an-arrow.

Of course, some of the newer clutch-type diffs aren't as aggressive as those
of yesterday and can be tuned by playing with the preload and/or pinion ramp
angles to accomodate the characteristics of a particular car and/or course.

Still, the Torsen (I use this term generically since there are several other
torque-sensing diffs on the market) is probably the best bet for most street
and race cars since it can distribute torque between the drive wheels before
one of them starts to spin and then in a infinitely variable manner ... just
wish they weren't so expensive and someone made one to fit my 4k's gearbox!

     _             _              _
    / l       l o l  \       l o l  \  _   _ o  _   _   AudiDudi@delphi.com
   /__l l l / l l l  l l l / l l l /  / l /  l l \ / _  Jeffrey Goggin
  /   l l_l \_l l l__/ l_l \_l l l  \ \_l \_ l l l \_l  Scottsdale, Arizona