Torsen Test

[Michael Stricker <stricker@ll.mit.edu>]

After receiving all of the "great" feedback regarding the Torsen 
differential Quattro drivetrain, I decided to perform an experiment this 
past weekend.  I admit that it is not the safest test but I had to prove 
that the Torsen setup really works.

The experiment was conducted in the following manner with 2 cars; The 
first was my 1990 Coupe Quattro and the second was with a 1987 5KTQ.

I placed a floor jack underneath the front crossmember of each car such 
that I could jack both cars front wheels off of the ground (of course, 
one car at a time).  I made sure that each of the front wheels spinned 
freely without the engine on or clutch engaged.  Next, I jacked ONE of 
the rear wheels off the ground so that it could spin freely.  One rear 
wheel was still on the ground.  Each of the floor jacks had the wheels on 
it so that the car could move if the wheel that was still on the ground 
received power.  NOTE: THIS IS VERY DANGEROUS!! Anyways, I started the 
Coupe up and kept my foot on the brake and the clutch pedal depressed.  I 
let the clutch out very gradually AFTER I took my foot off the brake 
pedal.  I could feel a slight surge, as if the car was going to move, so 
I took my foot completely off of the clutch and, NOTHING!  The car stood 
still while it was idling along at 1000 RPM.  I depressed the clutch 
pedal and turned on the DIFF LOCK switch and let my foot off of the 
clutch again and...still NO MOVEMENT!  I repeated the test with the 5KTQ 
and with center and rear diff's locked,  I couldn't take my foot off of 
the clutch because it was obvious the car was going to move.

Anyways,  that's my experience.  I can't see how the TORSEN differential, 
with the rear diff either locked or unlocked is going to get me out of a 
situation where I have traction at only one wheel.  It seems that at 
best, Quattro with TORSEN may be insignificantly better than front 
wheel drive when the rear WHEELS have traction and the front ones don't 
(I did feel a little surge but nothing significant).

What say the drivetrain gurus. Is my test conclusive in anyway?

Your input will be certainly appreciated.


Mike Stricker
1990 Quattro Coupe