Torsen

[Kennon Hines <kwh@bellsouth.net>]

Just adding my 2 cents to the debate:

1) I don't think the Torsen uses differences in rotational speed to
adjust the torque split.  I've always heard a Torsen will react even
before there is a rotational difference.  I think it actually "senses"
resistance at each output shaft and modulates torque accordingly.  It
should adjust for weight shifts and the like between the axles.  The
Audi engineering book I have says that the Torsen will actually send
more torque to the rear (front) when the car is going up (down) a hill.

2) The Torsen can be designed to offer different characteristics under
engine braking.  I'm not sure what type of setup Audi uses here.  It
will disengage completely if the clutch is engaged or if wheel braking
surpasses engine braking.

2) The Torsen in the new quattro IV system has a max split of 65/35
instead of 75/25.  I'm not sure why this is.  Also, the EDL operates up
to 80 km/h on quattros (it's 40 for FWD).

3) The Torsen can have a nominal split other than 50/50.  The new S4
does in fact have a slight rear bias.

I personally think quattro IV is the best traction management system
currently available for a passenger vehicle.  Audi would not still be
using the Torsen if they did not believe it to be the best device for
the application.

As far as gen. III goes, I've never had any problems with my CQ.  I
lived in the Colorado mountains last winter and saw plenty of ice/snow
pass driving.  The car was always completely controllable.  I could, at
my discretion, induce oversteer with power, but it was always easy to
correct.  I never experienced the now infamous "spider bite."

Disclaimer: the above reflects the opinions of a non-engineer who has
never driven a quattro at the track.  I know...

Regards,

Kennon Hines
1990 Coupe Quattro
Atlanta, GA