Torsen Tech

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <aae52c92.34f0a969@aol.com> QSHIPQ@aol.com writes:

> Jeff touched on a couple of points that really hit what the torsen is
> "thinking" while one carves into a turn.  Basically, the unit is sensing a
> slower rear wheel rotation on initial turn in, so more power is transmitted to
> the rear axle, per Jeff's post.  Let's explore that more fully to understand
> the handling of a Torsen at the limit thru a turn.

I don't think it's 'rotation rate' per se - it's torque.

> Turn:  90 right at the end of a long straight.  Dry track.
> Enter the braking zone.  Loading the cars' nose heavy front end, chassis
> dynamics will give intial understeer as you steer for the apex.  So, Entry
> Strategy (as per most fwd):  Late brake, oversteer before the apex, and drift
> out with power.  Not quite.  

The way _I_ drive the TORSEN, braking is over and power is back on before the 
apex.  Understeer never occurs - just a sideways drift.  Mebbe I'm doing it 
wrong, but I've driven 80000 miles in a TORSEN ur-quattro.  In line with your 
comment below, though, you _do_ need room.

> Next let's look at what happens beyond that oversteer, where you have the nose
> 90 degrees+ to the apex of the turn, the "expert" line.  Ok, so you've entered
> the turn, added throttle, back end comes out.  One of two things will happen.
> A)  in low traction, you keep your foot planted, and the torsen eventually
> will "find" that both axles are spinning at the same speed, and you have a
> 50/50 split.   OR B) You lost your balls and lift throttle.  <A> is a better
> proposition, but takes some serious practice to get correctly.  I saw a couple
> of posts (Jouko) that indicate that in an exercise this can be easily
> modulated.  I argue for a given turn or exercise maybe so.  For a full track
> or conditions which change, maybe not so.  

Option B) spins the car into the nearest marshall's post.  Ask Paul Beaurain.

> Given exercises at 11/10ths can make you better at understanding the "hunt",
> but I argue, not necessarily mastering it.  So that old "primitive" Gen I
> locking diffs, might just be a better setup for those looking for true
> performance driving.  For those interested in the 7/10ths world in which we
> drive day to day, the torsen is probably a good thing.  It certainly is for
> those (like my former wagon owner) who have never or don't use the knob
> supplied in the Gen I lockers.  

Interesting that Audi doesn't race the TORSEN differential.  It does seem to be 
a "consumer" device - like airbags.

-- 
 Phil Payne
 UK Audi [ur-]quattro Owners Club