Re: Torsen Test

["Graydon D. Stuckey" <graydon@apollo.gmi.edu>]

On Mon, 8 Apr 1996, Michael Stricker wrote:

> 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).


"Oooohhh, that hurts," said the Audi god as the blasphemy rose from the 
garage.  The ideals of quattro were under attack!  :-)

Seriously, the test merely confirms the theory, but you have made a false 
conclusion from the correct observations.

The Torsen diff acts like an open diff in general operation, but it is 
capable of transferring 2-3 times more torque to the wheel that has 
traction, as opposed to a regular open diff.  If you have a torsen on the 
rear axle, and do the conventional LSD test, the two wheels will turn in 
the opposite directions, like an open diff (great for cheating:-)  When 
you are driving on surfaces of slightly different traction, the Torsen 
will do a great job of transferring torque to the wheels that have the 
traction.  However, if you have two different surfaces that exceed the 
capability of the Torsen's torque bias, then you will get some wheel 
spin.  So, it is true, that a locked diff will get you out of more snow, 
but the Torsen will give you better handling on a race track.  I guess 
you have to decide for yourself which use your quattro will see most.

HTH

Later,								
Graydon D. Stuckey								
graydon@apollo.gmi.edu								
Flint, Michigan   USA
'86 Audi 5000 CS Turbo Quattro, GDS Racing Stage II				
'89 Thunderbird SC, pulley, wheels, suspension mods, 3.73 gear, and lotsa 
	toys inside 
'85 Mazda RX7 GS 12A-leaning-towards-a-13B-soon