Tornado //S6

Hey everyone. My dad and I are in the middle of replacing the center support bearing and front CV joint on my driveshaft and I thought I'd post some pics of the progress. The car is a 95.5 S6 with a 10/95 build date. Enjoy!

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Here is the car, the front resting on ramps and the rear on a pair of 6 ton heavy duty jacks.



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Here is the exhaust, in all its glory. Everything from the cats downward had to come off to access the driveshaft. Almost ALL of the bolts had welded themselves in there and had to be sawed off, so they will need to be replaced. In front of the cats you can see the various heat shields used to buffer the driveshaft from the hot exhaust, which runs right under it.



<img src="http://pictureposter.audiworld.com/11282/dscn5119.jpg">

Here is the driveshaft. The rear cv joint has the bag over it. The front cv joint is already removed(had to be hammered off). The center support bearing goes in the middle so the shaft had to be separated into two pieces at the u-joint. There is a bolt that needs to be unscrewed in order to separate the two halves but unfortunately, the bolt broke while trying to loosen it. We had to hammer the two halves loose and drill the remnants of the bolt out. Not sure if the bolt is even needed, since the two halves were nailed pretty tight together. We'll use a shorter one I guess, because the only way to insert it into the hole is thru the u-joint.



<img src="http://pictureposter.audiworld.com/11282/dscn5120.jpg">

Here is a closeup of the separation of the two halves of the driveshaft at the u-joint. The center support bearing goes on the beginning of the right half.



<img src="http://pictureposter.audiworld.com/11282/dscn5117.jpg">

Here is a comparison of the two support bearings. The new one is at the top, followed by the old OEM one, with the bearing and rubber removed. On the old one, the surrounding rubber part was cracked and wobbly, which resulted in driveshaft vibration. The new one is a Meyle BMW part, purchased from Darin N @ s-cars.org



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Here are the two support bearings again, this time one on top of the other. New one is at the bottom, old one at the top. Note the difference in the mounting bracket. Will have to fabricate something to make it work.



<img src="http://pictureposter.audiworld.com/11282/dscn5121.jpg">

Here is a comparison of the front cv-joints, new one on the left and old one on the right. The grease in the front cv-joint had turned into a pasty material and eventually the joint wore out. It's been loose and making clanking noises for quite a while now. The new CV joint is a porsche part, again purchased from Darin N.



<img src="http://pictureposter.audiworld.com/11282/dscn5128.jpg">

Here is the front mounting point for the driveshaft, at the torsen differential. The grease is all dried up and pasty and will need to be replaced.



<img src="http://pictureposter.audiworld.com/11282/dscn5126.jpg">

Here is the rear mounting point for the shaft, at the rear diff. The grease here is good and plentiful and therefore the rear cv joint is in good shape.



<img src="http://pictureposter.audiworld.com/11282/dscn5127.jpg">

Here are the elusive parking brake cables, which are damn near inaccessible with the exhaust in place

I will post more pics later. This is Day 2 of the project....all of the old bolts on the exhaust still need to be removed and replaced and everything reassembled. Hopefully the car will be ready in time for waterfest. Thanks for looking!

Rokas

Roger @ CA

Great writeup and pictures, hope you can make it with us.

EvanUrS4

Thanks for the cool pictures and good luck with the project.

YumyJager

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Tornado //S6

There is no separate direct OEM replacement bearing for these cars, altho there IS a part # on the old bearing housing...

YumyJager

I'd ask the S list how they did it.

parkpy

Tornado //S6

I would, if I had three things...1) new clutch 2) resurfaced flywheel 3) time...:-)

Wayne Dohnal

I had some vibration and a sagging driveshaft center bearing in my '94 S4 with 195k miles and decided to tackle the driveshaft. I would have been lost without the lead post in this thread, but I can add some details for anybody thinking of tackling the job. A number of people have reported replacing the front CV and center bearing with good success, which is what I set out to do. But I drew the short straw and ended up with a 3-month ordeal that included installing the driveshaft 3 times, and wasting a bunch of money. My problem was that the center u-joint was also shot with end play, which wasn't detected until I took the driveshaft in to be balanced after 'fixing' it and putting the car back together. It vibrated worse than ever after replacing the front CV and center bearing.

As others have reported, my front CV was all dried up and shot. The center bearing support was badly sagging but the bearing itself was ok. But in mine the rear CV was also noticeably worn. It wasn't dried out and didn't have rotational play, but had obvious 'notchiness' when moving it. The cost of both CVs and a center bearing starts to approach the cost of a rebuilt driveshaft. With my rear CV also worn I would have been better off going with a rebuilt from the start. It's somewhat difficult to detect the end play in the center u-joint without spinning-up the driveshaft. I eventually went with a rebuilt. In addition to all the time I took working on it, a big part of the 3 month downtime was from the rebuilders waiting for backordered CVs, and version 1 of my rebuilt driveshaft had a wrong center bearing support.

Some comments on the actual R&amp;R job:

1. Don't even start unless you have a T-47 Torx bit available to pull the heat shield on the back of the transmission. And watch the 4 spacers: They look firmly attached but they like to fall off and silently roll away.

2. It's a pretty nasty job for 1 person lying on the floor. Doing it on a lift with a helper available would be the preferred way. The driveshaft is a pain for 1 person to wrestle with.

3. I pulled the entire exhaust as shown in the original post. If you drop the cats onto a creeper, you can then grab the pipes on the rear and just wheel the whole thing out from under the car.

4. 3 of the 4 rubber exhaust hangars can be removed by prying them off or unbolting the top supports. Having done it both ways, I prefer unbolting the supports. But the hangar by the rear diff has to be stretched back on after reinstalling the support, and it's a nasty one.

5. Using a table saw I made an alignment fixture out of a 2x4 and plastic drain pipe cut in half the long way. It was good for alignment, but the main benefit was its turning the driveshaft into one rigid piece for moving it around. It's pretty hard for one person to move the driveshaft without flexing the center u-joint probably more than it should be. As heavy as it is (about 28 lbs) it took very tight bungees to hold the driveshaft to the homemade fixture.

6. The Bentley says to R&amp;R the driveshaft while it's held straight in the alignment fixture. Forget that one. It's just too long to get in and out without dropping the center at least a few inches. All I accomplished trying it the Bentley way was wasting a lot of time, ruining one of the gaskets, and getting grease all over the place.

7. This is the best opportunity you'll ever have to easily replace the parking brake cables.

8. Separating the halves was very difficult. The bolt was easy, pounding the halves apart took a couple of hours.

9. If you replace the center bearing, note that the support is not symmetrical.

The big problem in repairing the driveshaft is the staked-in center u-joint. There are only a very limited number of companies that can replace it. There's a major driveshaft company near me in Portland, OR. that replaces the staked center u-joints for BMW and Mercedes, but they don't have the tooling to do Audis. Blau has a do-it-yourself kit which I didn't pursue.

I found only 2 companies that do the work: Driveshaft Specialist (www.thrashdriveshaft.com) and Powertrain Industries (www.driveshaft.com). Maybe there are others. Some of the other online sources trace back to one of these companies. For all I know, they might even be related to one-another. I went with Driveshaft Specialist and will recommend them. I had a hiccup with the first replacement arriving with a wrong center support. That's bad news but gave me the opportunity to see that they provide excellent customer support, going out of their way to quickly straighten out the problem. On the 2nd try they used my original center support bracket and all worked out well. If you do get a rebuilt make sure they understand ahead of time that the S4 center support is asymetrical. Apparently most Audi center supports have the bearing centered between the mounting holes. It's probably best to just send them your driveshaft to be rebuilt. It adds the hassle of increased downtime and making your own shipping box, but then you know for sure everything should fit correctly the first time. Contact them before taking the car apart to make sure they have the parts, and for shipping assistance.

The job was a lot worse than it should have been, but it's good to have the ole' gal back on the road again.