Torsen differential

Thu Nov 14 10:21:19 EST 2002

[ Picked text/plain from multipart/alternative ]
A couple points.  First, the Torsen isn't bulletproof, it wears or breaks,
that's all.  It's not meant to handle large torque applications in the audi
application.  Heavy equipment is actually going towards the Haldex systems,
not the torsen systems.  The main reason you see torsen centers is the
ability to use ABS AND EDL with no human interaction.  Current audi applic
ation torsens are 75/25/75 or 78/22/78 in the pre nue S4 cars, depending on
which audi literature you read.

More than a few folks would say that torsen is "new tech", even audi
considers it "old tech" and is well on the road to haldex equipping quattros.
 The reason you are seeing some of the players coming to torsen late in the
game is just plain money.  Most of your buyers don't off road, don't put the
device at the limit, nor want to have ABS/EDL disabled under full lockup.  I
wouldn't make the jump with you that this makes it a great traction device
(search the archives for volumes).  Can it last the lifetime of the vehicle?
Sure.  Is that the definition of "bulletproof"?  Not to me, but it could be.

When the urS4 and the neu S4 are raced, few are using the torsen (stasis
appears to be the exception), many have had problems with breakage, and the
most rules allow welding of the diff, which tends to keep the breakage
problem at bay.  The offroad racers evaluated and ditched them because they
broke quickly.

What's "new" in terms of technology?  The haldex.  The Haldex engineers claim
that audi could use it in "fulltime" awd mode (actually *they* wonder why
audi doesn't do this), and that the torque levels are virtually limitless
(haldex roots is as heavy equip supplier).  Audi is actually late in the
haldex game, since Jeep has been using the haldex type center diff in their
SUV's for a couple years now.


Scott Justusson
Ascribed torsen antichrist and
Locker dude
In a message dated 11/13/02 9:58:52 PM Central Standard Time, Jim A writes:

Yes, obviously towing is an issue.  This is covered
with a SEVERE warning in the owners manual.  As far as
bulletproof, I can only speak from my own experience.
I am by no means easy on either the clutch or the loud
pedal and when the rear output bearing on my center
diff. took a crap (unrelated to the Tors*n), I pulled
it out, cleaned it off and gave it a thorough visual
inspection (FWTW), and it looks nearly new.  NO
visible wear (match marks, discolored metal, filings,
what have you) on the Tors*n itself.  We're talking
220K (not necessarily so easy) miles.  I don't really
know how else to describe this.  Also that diff. has
become "der regere" in heavy construction equipment.
Would they spec. this in articulated end dumps if this
technology sucked?  CAT, Volvo?  Somehow I don't think
so.  I have no knowledge of what the PO did for the
first 140K miles.  maintanence maintanence, or bad
shifting techniques could have caused the demise of
the rear output bearing.  All the more reason to
suggest the bulletproof nature of the Tors*n.  IF he
crapped out my tranny and the Tors*n still looked so
clean, what more info do I need?

Jim Accordino

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