Re: Torsen stuff

[Jeremy R King <kingjer@Eng.Auburn.EDU>]

Please correct me if you know different, but here's how I understand the 
Torsen setup.  A Torsen differentiates between front and rear based on 
available traction.  If the rear looses traction, most of the drive 
torque is sent to the front tires and vice versa.  The front differential 
is an open differential and differentiates between the right and left 
front tires.  An open differential sends more torque to a spinning wheel 
once it starts spinning.  This results in the wheel with traction not 
getting any of the drive torque.  My understanding is that the older 
lockable q's had a lockable rear differential.  Thus you always had at 
least one wheel with traction AND drive torque, so you could get out of 
slick situaion as long as your one tractioned wheel wasn't in the front.  
Even then, it would work better than what I'm about to describe.  It 
sounds as if you have an open diff in front AND back, with a center 
Torsen.  So if you have one side (say left front and rear) tires on ice, 
the Torsen sends equal torque to front and rear.  But because of the open 
diff up front and in back, all of that torque is sent to the left side of 
the car (ie the side with no traction).  So for you to benefit from 
quattro on your model, you'd have to have traction on either both front 
wheels or both rear wheels at the very least.  Of course the ultimate 
would be Torsens all around - the V8 had a center and rear Torsen with 
and open diff in front for a year or so (eliot?).

Is that clear as mud now?  Am I mistaken about the rear diff being open?

On Wed, 3 Apr 1996, Michael Stricker wrote:

> Hi;
> 
> My message regarding the Torsen drive train was in regard to a recent 
> experience I had...I was in a situation where I was going down a hill and 
> the whole road turned to ICE.  I drove my car as gracefully as I could 
> such that the passenger's side of the car( front and rear wheels) were on 
> soft powder snow and the driver's side wheels were still on ice.  My 
> theory was that I would have traction via the passenger wheels and thus 
> would be able to have some control.  Needless to say, my car didn't move 
> at all.  I agree, that with all four wheels on a flat icy surface, I can 
> accelerate slowly but in the situation I was in, NO GO.  The experience I 
> had with the TORSEN set-up in my 90 Coupe was vastly different than what 
> I had expected and what I have experienced in my older Quattros with the 
> manually lockable differentials.  
> 
> This led me to my question/comment.  The other thing I've noticed is that 
> the cars with Torsen will hydroplane whereas the older cars never 
> did...even with tires that were virtually bald.
> 
> I am contemplating swapping out my Torsen equipped transmission and 
> replacing it with one containing a center differential.  Other vehicles 
> use this Torsen feature (such as the HUMMER) but perhaps they have the 
> torque bias set at different levels.
> 
> That's about it.
> 
> Mike Stricker
> 1990 Quattro Coupe
> 1993 Merlin EL (road)
> 1993 Raleigh John Tomac Signature
> 
> P.S. It's time for some 2 wheel racing!
>