'87 4kQ bad (?) tranny update, long, q's at end...

[Lines Peter]

If it's noisy with the center diff open, but quiet with it locked, I would
have to assume it's something wrong with the four spider gear in the diff or
the locking ring system?  I know there is a plastic shim/bearing behind each
of the four spiders in the diff.  Maybe it's toasted?  Maybe one or all of
the spiders are trashed?  Maybe the noise you are hearing is some sort of
ratcheting due to the diff not completely unlocking?
I would tend to think that the faulty actuator may have something to do with
it.  I'd get that part in good working order, then continue to test.
Another thing to try (I know you probably don't feel like crawling under the
car at this point): Disconnect the propshaft, set the front wheels on the
ground (or have someone step on the brake), put the tranny in gear with the
engine off.  Then use one hand to pull the diff linkange open.  With the
other hand, rotate the rear flange.  You should be able to rotate it easily,
with no noise or grinding.  Then slowly move the linkage to engage the diff.
You should feel point where the clutch ring engages and you can no longer
rotate the flange.  Repeat.  Results?
If you want to inspect the clutch ring, you can remove the rear mounting
plate on the tranny with 3 screws.  The rubber damper, cover, diff lock
spline, and output flange will all come off.  This will let you look inside
the tranny to see if the clutch ring teeth have gotten hammered.  The next
step is to remove the rear housing which will allow the entire center diff
to come out.  There are 10-12? screws holding this on, which should be
accessible if you remove the tranny mounts and lower the rear of the tranny.
Sorry I can't help you source the small parts in Detroit.  I've gotten kind
of spoiled living in Portland with the U-Pull-It yards.  I can grab some
items if you are desperate.  I know of at least 2 type 44's with the quattro
trannies in them.  I have to assume the diff parts would be the same,
although the whole tranny wouldn't work in your car.

Peter Lines
CAE System Administrator, WARN Industries
p: 503.659.8750 x4116
c: 503.319-3739
f: 503.786.4463
peterl at warn.com; www.warn.com