need help diagnosing drivetrain problem on 90q20v

[Dave Eaton]

dan,

the behaviour you mention with the car up on blocks is normal for a torsen
car.  the only way to check the rear would be to only put the rear in the
air, and have the front on the ground and securely chocked.  you'll hear a
thunk (the torsen unlocking), and the rears should turn.  don't worry, the
car won't move - if you don't believe me, use 5th gear to be extra comfy...

from your other symptoms, i'd suspect rear handbrake callipers sticking, or
diff operation.  do both sides of the diff spin freely?

hth,
dave
'95 rs2
'90 ur-q
-----Original Message-----
Date: Sat, 11 Aug 2001 11:08:17 -0500
From: Dan Simoes <dans at audifans.com>
To: quattro at audifans.com, audi-20v at rennlist.org
Subject: need help diagnosing drivetrain problem on 90q20v

I put the car up on blocks, removed all 4 wheels, and was hoping to see
3 wheels spinning.  Instead, I see the fronts spinning and nothing
happening in the rear, nothing in the prop shaft either.  WTF?  Bad rear
diff?  Bad carrier bearing in the shaft?  With the car running and in
gear, I can "help" the prop shaft and see both rear halfshafts turning,
so I know the diff is not seized.

Now that I'm up here typing this, I'm wondering if the Torsen center
diff is not sending power to the rear because there is no traction.  I'm
not positive about this though.  Assuming the rear is OK, that brings me
back to either a bearing or caliper in the rear left.

Another weird thing - the rear diff never worked although the switch
lights up when you press it.  Well, right now the ABS off light is on
and the green LED indicates the rear diff is locked.