View Full Version : Question about replacing the rear differential pinion seal

02-25-2015, 01:38 PM
Happy hump day.

I'm in the middle of replacing the seals on the rear differential of my brother's 2000 Quattro car and have run into a stopping point. The axle seals have both been replaced no problem, it's the front pinion seal that is giving me some trouble.

I've got the snout pulled off from the pumpkin and I've already pulled the male-male spline connector off the shaft in the snout. I'm having trouble removing the flange/shaft from the snout so I can get to the seal behind the flange though. I've been working off this (http://www.audiworld.com/forums/a4-b5-platform-discussion-1/b5-rear-diff-tail-piece-seal-change-2826205/) thread and followed the advice of using two bolts to push the flange out, however it really doesn't want to budge. I'm worried about damaging the threads on the flange or the housing casting if I apply more pressure. I do have a shop press I could rig up to press the shaft out, but that introduces new sets of worries (like breaking the bolt flanges off the housing or cracking the shaft.)

Should I just keep driving the bolts into the flange? Rig up the press? There is the option of taking it to the local Audi shop and having them finish the job as well, but I'd rather knock it out myself.

Anyone done this job and have any advice? Mtroxel?

Diff separated.

http://i346.photobucket.com/albums/p439/blkA4alb-3/Chris%20B5/DSC08274_zpsw6uodsp0.jpg (http://s346.photobucket.com/user/blkA4alb-3/media/Chris%20B5/DSC08274_zpsw6uodsp0.jpg.html)

Pulling the coupler off.

http://i346.photobucket.com/albums/p439/blkA4alb-3/Chris%20B5/DSC08277_zpsrsxeacq4.jpg (http://s346.photobucket.com/user/blkA4alb-3/media/Chris%20B5/DSC08277_zpsrsxeacq4.jpg.html)

Bare shaft.

http://i346.photobucket.com/albums/p439/blkA4alb-3/Chris%20B5/DSC08280_zpsg17jlqac.jpg (http://s346.photobucket.com/user/blkA4alb-3/media/Chris%20B5/DSC08280_zpsg17jlqac.jpg.html)

02-25-2015, 02:05 PM
I did a little digging and came across this diagram for the break down. I don't know if you've seen this or not. I does look like there could be some sort of snap ring.
http://i254.photobucket.com/albums/hh91/bshusted/reardiff_zps595sn3yi.png (http://s254.photobucket.com/user/bshusted/media/reardiff_zps595sn3yi.png.html)

02-25-2015, 02:45 PM
I hadn't seen that, thanks. It helps to lay things out more clearly.

25 is the coupler that I pulled off in the second picture. In the third picture you can see the shaft sticking out from a hole in the snout housing. At the other end of the snout is the flange where the driveshaft bolts up. 26 through 30 must be between the flange and that plate that the end of the shaft is sticking out of. So it doesn't look like the snap rings at 27 and 29 could be holding the shaft in place or it would be impossible to remove, I suspect them to be holding the bearing in place.

Edit: I wonder if 26 is the plate that the shaft is sticking out of..maybe that plate comes off somehow. Going to go check it out.

02-25-2015, 09:42 PM
I believe I found the culprit. Big shout out to Curly at Griffin Motorwerke for talking it over with me and pointing me in the right direction.

I thought I had inspected the diff pretty well, but I missed this snap ring that was basically hidden underneath the diff mount. The snap ring is also absent from the diagram above. Unfortunately the snap ring pliers I have are too small so extraction will have to take place tomorrow after I get a proper set of pliers. Hopefully after removing the clip and pulling that thing out the shaft just slides out. Fingers crossed.

You can see it off to the left edge of the mount.

http://i346.photobucket.com/albums/p439/blkA4alb-3/Chris%20B5/DSC08281_zps0xqcj4ox.jpg (http://s346.photobucket.com/user/blkA4alb-3/media/Chris%20B5/DSC08281_zps0xqcj4ox.jpg.html)

http://i346.photobucket.com/albums/p439/blkA4alb-3/Chris%20B5/DSC08283_zps6q4h4vvj.jpg (http://s346.photobucket.com/user/blkA4alb-3/media/Chris%20B5/DSC08283_zps6q4h4vvj.jpg.html)

02-26-2015, 07:43 PM
Over the top of the hill now, all the disassembly and replacing of seals is done, now onto reassembly. When I'm done I'll write up a full article.

I've made quite a few dumb errors, like not even checking my Bentley manual to see if this job was in the book (which it is.) Would've saved me a lot of headache had I just used the resources I had at hand. The c-clip I posted above was also mentioned in the article I linked in the OP but I glazed over that part.

Anyways, here's the c-clip that actually holds the shaft in place that is below the cap posted above.

http://i346.photobucket.com/albums/p439/blkA4alb-3/Chris%20B5/DSC08284_zpsllzdawew.jpg (http://s346.photobucket.com/user/blkA4alb-3/media/Chris%20B5/DSC08284_zpsllzdawew.jpg.html)

And here is the shaft removed (snap ring pliers for scale.)

http://i346.photobucket.com/albums/p439/blkA4alb-3/Chris%20B5/DSC08290_zpszlgvti5c.jpg (http://s346.photobucket.com/user/blkA4alb-3/media/Chris%20B5/DSC08290_zpszlgvti5c.jpg.html)