Center Driveshaft
        Lubricate
        R&R
    Rear Differential Oil Seal Replacement
    Motor Mounts and Suspension Bushings
        Changing Motor Mounts
    The dreaded Torsen Differential
    Rebuilding the tranny

Lubricate
Look at the connection point, just above where the rear diff is and look in there. Use a flashlight. You will see a small square looking piece that is slightly sticking out in that joint there. On (or in) that square piece is a little hole. Get your can of spray white lithium grease and spray some in there. Refer to section 39.22 of the Bentley manual. It said to do this approx every 10K miles. Most have NEVER been done! It has to be in a certain position to really get at it right.  (Some cars may not have this; mine does).
 

R&R
If your center driveshaft bearing goes bad (driveline noise between center
and rear diffs), you have three options. Audi says that you have to buy the
whole driveshaft for big $$$. Blaufergnugen will rebuild it for you for less
$$$. Or you can try the following for relatively few $. Be forewarned: The
procedure below was performed on an ur-q and 4Kq, so I'm not sure the part
numbers listed will work on our 20V models; you may have to do some
detective work.

It seems that the whole carrier assembly is available that includes bearing
and the mounting rubber. Catch, this is a BMW part (26 12 1 209 532). Cost
of this part is around $35 from GPR (800-321-5432) and has the advantage of
replacing all the mounting rubber although the rubber isn't usually bad.
They also have drive shaft CV Joints for $93 each.

Special Tools: Other than metric socket & openend wrenches all I needed was
one of the 12 point modified hex keys that is needed to remove the socket
cap bolts that hold the CV joints to the drive flanges. Bentley shows a
homemade alignment tool (which I didn't make).

Parts Needed: It is recommended that the CV joint seals be replaced, these
seals go between the CV joint and the drive flange and are available from
the dealer. 911 Turbo cvjoints fit.  Part number for the cvjoint is 951 332 901 00.
I don't have part numbers for the bearing or ujoint, but the
bearing is a standard FAG part. I was able to get a replacement for the
ujoint by measuring the dimensions of the cap & spider (This was necessary
because I broke one of the needle bearings when I was putting it back
together! BE CAREFUL)

Bentley's Caveats: Do not bend driveshaft, always store and transport in
parallel position. Tie up shafts when removing and installing driveshaft.
(If you've got the car up on a rack it might be possible for the driveshaft
to hang down far enough to cause a problem. If you are working under a car
on jack stands all that is probably needed is to protect the CV joints from
contamination.)

Driveshaft, Removing: (From Bentley) Detach driveshaft from transmission
flange. Tie up shaft end. [I recommend putting a heavy duty plastic bag
(ZipLock) over the end of the CV joint.] Detach driveshaft from rear final
drive flange. If necessary engage differential lock and block wheel. Tie up
[and bag] shaft end. Detach center bearing from body and take out
driveshaft. You might want to test the axial bearing and ujoint at this
point to verify that they need to be replaced! The bearing might have a
gritty feel as it is turned or make noise as the housing is spun as fast as
possible.

Now that you've got the driveshaft out you will see that there is a nut that
holds the fore end of the ujoint yoke to the the foreshaft. It was not
possible for me to fit an openend wrench in there to loosen the nut until I
had disassembled the ujoint & yoke (but I would recommend trying it because
it would certainly be preferable to keep the ujoint intact). This was done
by removing the spring clips for the cups in the foreshaft yoke and then
using a socket as a drift punch to remove the cups. It is probably much more
civilized to create a makeshift press using appropriately sized sockets and
a bench vise. It should be possible to remove the spider from the foreshaft
yoke after both cups have been removed, but it seems to me that I removed
all 4 cups for some reason. I recommend keeping track of which cup attaches
to which leg of the spider, but that probably doesn't matter since they are
machined parts. While you're at this point it is possible to check for
proper lubrication of the bearings in the ujoint and scoring on the bearing
surface of the spider.

With the ujoint disconnected from the fore yoke it should be possible to get
a socket in there to loosen the nut. I held the foreshaft in a vise to keep
it from turning. Once the nut is removed the yoke can be taken off (it is
splined to the foreshaft. You may need to squirt a little penetrating
lubricant in there to help. Once the yoke is removed the axial bearing and
housing can be removed from the foreshaft. The bearing was not pressed on,
but it did take a little work to get it off.

Looking at the bearing & housing it will be apparent which way the bearing
comes out. It is pressed in, but it isn't too tough to press the bearing out
with a mallet and something large enough to keep the housing stationary (I
don't remember, but I probably adjusted the width of the vise jaws to be
about the OD of the bearing and then used a socket as a drift punch (love
that Craftsman guarantee :) It wouldn't be a big deal to take the thing to a
machine shop to do it right. The part number for the bearing can be read at
this point and a suitable replacement procured. The original bearing was
made by INA with a part number of: 6006RSR The replacement was made by FAG
and had a few more numbers on it (at least the box had more numbers):
6006.2RSR.T.C3

Reassembly is the reverse of disassembly, but be very careful when
reassembling the ujoint. It is tough to know if one of the needle bearings
has fallen into the bottom of the cup while you are driving the end caps
back onto the spider. As I recall I had to insert the spider into the
foreshaft yoke (after reassembling the foreshaft, bearing & housing and
foreshaft yoke of course!) and then install the cups by hand. It is probably
best to use a vise to get the cups inserted as far as possible into the yoke
(maybe even all the way with the help of a couple of sockets). Then replace
the spring clips and you're ready to reinstall the driveshaft in the car. Go
ahead and grease the ujoint before installation (service interval is 15K
miles). Also remember to clean off the sealing surfaces on the CV joint and
the mounting flanges and to replace the seals when everything goes back
together.

Tightening torques:

   * driveshaft/trans. flange 55 Nm(40 ftlb)
   * driveshaft/final drive flange 55 Nm(40 ftlb)
   * center bearing/body 20 Nm(14 ftlb)

NOTE: Driveshaft must be adjusted during installation. The Bentley manual
has several pictures and special tools for adjusting the driveshaft during
installation. The whole idea of the procedure is to ensure that the two
halves of the driveshaft are as co-linear as possible. During installation
the center bearing housing can be adjusted up & down with shims and left and
right with slots in the mounting holes on the housing. I marked the bolt
locations on the housing and installed the same shims that were originally
present.

(from a coupe quattro procedure: should be the same for the type 44)
The size of the allen wrench to remove the drain and fill plugs is 17mm.  Sears sells one; you can also buy a socket made by Snap-On (and others) that is finished with a 17mm hex end.  Much easier than the big allen wrench; less likely to slip and strip the plug.  Others have cut a section off the allen wrench and used it with a socket, or just used a 17mm-head bolt with nuts on it with a wrench.  I think I paid about $14 for the Snap-On piece.

To check, just remove the fill plug and put your finger in the diff.  If you can touch oil or feel it, or it slightly leaks out, then you should be ok, but adding a little extra never hurts, as too much oil will simply flow out the fill plug.  On the transmission up front, Audi actually recast the case to allow more tranny fluid by tapping the fill slightly higher.

Eventually, you will need to change the seals on the rear diff. I've replaced the diff seals on my rear diff (halfshaft seals only, not driveshaft seal).  For both seals, you need to unbolt the CV joint for the half shaft only at the diff, then push the halfshaft up and out of the way so that you can pry out the seals.  No need to remove the tires or suspension components.  To remove the bolts, you'll need a special tool which looks like a hex key but it is actually an 8mm 12 point key as opposed to the 6 point hex keys.  You can probably (not sure) buy this at German Parts and Restoration or they might know where to send you for this tool ..... I think I bought one years ago at NAPA for my VW.  Hazet is the only company I know of that makes it, life time guarantee.

Next you have to remove the bolt that holds the half shaft flanges to the diff.  These bolts are about 3" long and are removed with a 6mm allen key or hex key.  This is easy, requiring only two of the CV joint bolts and a pry bar between the two as a wedge to prevent the flange from turning.  These bolts aren't torqued in too tight anyway.  Only one thing to be VERY careful of ...... there is a shim which looks a lot like a very flat, thin washer placed between the driver's side flange and the diff gears .... DO NOT LOSE THIS SHIM!  Also, they vary in thickness from car to car, so it's not like you can just by the replacement part.  The passenger side can safely be removed with out worries, as there is no shim on passenger side.

The seal on the driver's side is like over 3" in outer diameter and approx. 2" inner diameter (about 80% sure of this).  This one is somewhat of a pain to remove/install because of the size.  I used a pipe of just under the outer diameter and 1" long to drive in the seal with a hammer.

The seal on the passenger side is a cake walk ... approx. 1.75" outer diameter (about 70% sure of this).  Once again, I used a short piece of pipe with a slightly smaller od than the seal.Once the new seals are in, put the flanges back in and tighten them up to about 20 lb-ft of torque using, once again, two of the CV joint bolts and a prybar to prevent the flanges from turning while tightening.  DON'T FORGET THE SHIM ON THE DRIVERS SIDE!!!

Now you can put the half shafts back in place and tighten up their 6 bolts to 33 lb-ft of torque.  Also, it's a good idea to try (tough one though) to add grease to the cv joints while they are exposed and add loctite blue to the bolts that hold the cv joints to the flanges.

If you do decide to replace the diff seals, do both, not one, as it's almost guaranteed the one that wasn't changed will leak in a very short time, besides, they are pretty affordable from the dealer.  Also use 75w90 synthetic diff oil .... I like the Castrol synthetic stuff.  You might notice the diff will run quieter after this work is done.  Good luck in what ever you decide to do.
-<{Quattro 20V Boy}>-

After several years of loyal service, all of the stressed rubber bits
(suspension bushings, engine/trans/rear diff/front and rear subframe mounts)
will stop doing their little bit. The car will feel *like new* when you
replace them.

Changing Motor Mounts

  1. Car on ramps.
  2. Put a jack/stand on the motor as close to the mount as possible. If you
     can't, you can use a 2X4 from above with chain/rope (this keeps the
     motor from stressing the opposite mount during swap, and keeps mount
     close to frame rail to put on 15mm nuts).
  3. Remove upper mount nut (19mm I think) may want to soak it a couple of
     days with WD-40, it tends to catch water by design. The problem is, if
     the mount is spinning in the cup, you might have some time getting nut
     off.
  4. Remove lower mount nuts (2X15mm). The engine is now resting on jack or
     hanging on rope and the trans mount only.
  5. Pull mount down and out.
  6. Install new mount from below, 15mm nuts on first.
  7. Install top nuts, torque to spec.
  8. Remove 2X4/jacks.
  9. Off ramps.

torsen white paper link
http://www.mindspring.com/~audidudi/Torsen.htm

discussion board http://www.greenspun.com/bboard/q-and-a.tcl?topic=Torsen%20diffs%20and%20AWD
 
 

Rebuilding the tranny

From: Gary.Lewis-at-West.Boeing.com (Lewis, Gary M)

Hi All,
My mechanic here on the left coast can rebuild a 20v tranny (or an S4 tranny, or a V8 tranny, or a...).  He is factory trained, been working on Audi's since 1979.  And he's cheap.
Mike Rooney
Ingolstadt West
818-713-1953

Gary

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