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REPOST: Propshaft/Axial Bearing Service Info



Here is a collection of information that I have generated myself on the
subject with a couple of related qlist posts ... I think that it is pretty
much in shape to serve as a prototype for the new webpage system ... AAMOF,
I have probably already given Dan a copy of it some time back.  

Let me reiterate that I was able to rebuild the carrier bearing on my '83
QTC by purchasing a stock bearing from a local company ... and from Jim M's
post from within the past 24 hours, it appears that at least some 4kQs are
the same.  I wish I could only find the box for the replacement u-joint that
I used ... it has the zerk fitting ...

HTH!
Steve Buchholz
San Jose, CA (USA)

From: 		Steven L. Buchholz
Subject: 	Driveshaft

Procedure - Replacing axial bearing (&/or u-joint) on quattro driveshafts

A few years ago I had a noise that came from the driveshaft between the
center 
to rear diffs.  I found that Audi considers the driveshaft to be a single 
replaceable unit, so individual repair parts are not available for it.  I 
took the driveshaft off the car and found that it was not too difficult to 
disassemble and the bearing & u-joint were available from non-dealer
sources.  
This was done on an '83 ur-Q.  I am including information from pages 
39.42-39.44 of the Audi 4000S, 4000CS and Coupe GT Official Factory Repair 
Manual 1984-87 Including Quattro and Quattro Turbo.  Here is a quick rundown

of the procedure:

SPECIAL TOOLS: Other than metric socket & open-end wrenches all I needed was

    one of the 12 point modified hex keys (AKA triple-square bit) that is 
    needed to remove the socket cap bolts that hold the CV joints to the 
    drive flanges.  Bentley shows a home-made alignment tool (which I didn't

    make).

PARTS NEEDED: It is recommended that the CV joint flange seals be replaced, 
    these seals go between the CV joint and the drive flange and are
available 
    from the dealer.  I was able to get a replacement for the u-joint by
meas-
    uring 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)

*****
On my car the original axial 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
*****

SUGGESTIONS: Mark the positions of the two bolts that hold the axial bearing

    assembly to the underside of the car so that you won't need to adjust
the 
    driveshaft when it is reinstalled.  It is probably a good idea to mark
the
    halves of the driveshaft so that they can be reassembled the same as 
    originally.  The driveshaft is a balanced assembly, which in most Audis
    when running in top gear is rotating slightly faster than the engine.

BENTLEY's CAVEATS: Do not bend driveshaft, always store and transport in
par-
    allel position.  Tie up shafts when removing and installing driveshaft.

STEVE'S OPINION OF BENTLEY'S CAVEATS:  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
prob-
    ably 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.

[Installation is the reverse of removal]
NOTE: Driveshaft must be adjusted [during] installation

Tightening torques:
driveshaft/trans. flange       55 Nm(40 ft-lb)
driveshaft/final drive flange  55 Nm(40 ft-lb)
center bearing/body            20 Nm(14 ft-lb)

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 hous-
ing.  I marked the bolt locations on the housing and installed the same 
shims that were originally present.  
***
AFTERTHOUGHT INSERTED AT AN APPROPRIATE LOCATION:  You might want to test 
the axial bearing and u-joint 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 u-joint yoke to the the fore-shaft.  It 
was not possible for me to fit an open-end wrench in there to loosen the 
nut until I had disassembled the u-joint & yoke (but I would recommend 
trying it because it would certainly be preferrable to keep the u-joint 
intact).  This was done by removing the spring clips for the cups in the 
fore-shaft yoke and then using a socket as a drift punch to remove the 
cups.  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 u-joint and scoring 
on the bearing surface of the spider.  
***
ANOTHER AFTERTHOUGHT: I used a mallet and sockets to disassemble the u-
joint.  It is probably much more civilized to create a makeshift press 
using appropriately sized sockets and a bench vise.
***
With the u-joint disconnected from the fore yoke it should be possible to 
get a socket in there to loosen the nut.  I held the fore-shaft in a vise 
to keep it from turning.  Once the nut is removed the yoke can be taken 
off (it is splined to the fore-shaft.  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.

Reassembly is the reverse of disassembly, but be very careful when reassem-
bling the u-joint.  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 fore-shaft, 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 u-joint 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.  

All in all the procedure is not too involved and I'd rather do this than 
change a stupid water pump!  I replaced the bearing on the ur-Q shortly 
after I got the car, and it's given me ~8 years of trouble free service.  
I have tried to be thorough in my description, but feel free to contact 
me if you need further clarification!  I'd also like to get some feedback 
on particular models and years to find out whether or not this procedure 
is generally applicable.  

Steve Buchholz
s_buchho@kla.com
12 September 1996

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