OK. I got it back together and the car shaking vibration at 45-50 mph is gone. I noticed one of the bolts on the front flex disc had the center section of threads worn away so that's not a good sign. Also the flex discs while not terrible did have hairline cracks. The rubber on the carrier was really bad and the bearing was rough. I was able to rip the rubber carrier off the bearing by hand.

Of course in any situation like this now that that major vibration is gone I notice other vibrations which sound like they are coming from the rear of the car. This one is more of a rattle so I'm thinking rear sway bar links. Also the CV boot is split so I need to address that as well.

Overall thanks for the help!

I started with one and then two per bolt (2). Two did the trick although I had to get 1/8 inch longer bolts. Washer were common machine washers for the bolt picked up from the dealer. Sorry don't know the thickness figure.

I am going through this right now with our 85 TD. My wife drives the car daily. While away, I had a mechanic check it out and he found the center bearing coming apart. I had him replace it. I asked for pics of the parts on the entire shaft and got nothing. The part was installed and it was ok for a couple months. I am now visiting, and the car had a terrible banging sound. I could not believe my wife was driving it.
I took it apart the next day and found the new center bearing destroyed and both flex discs badly worn, if not nearly trashed.
I ordered new discs, center bearing and bushings. There was no listing for the u joint. I guess I am going to have to order that by dimensions. (??)

I have the driveshaft back together with a notchy u-joint. We will see how well it drives tomorrow.

Question here is, where to get a new u-joint?

Fingers crossed the center bearing doesn't fail again until I get that joint replaced. My wife loves this car and is chomping at the bit to drive it again.

You can find a new U joint but there is a whole lot of problem installing it as the factory didnt use any clips or locks - they locked it into place by making indents on the bearing side of the U joint yoke.

If you can find a driveshaft shop that can replace it for you - you win, otherwise you will need to exchange your D shaft for a rebuilt one.

Last fall I was redid the entire rear end including
both flex discs. The U joint was notchy. I tried buying a whole
"new" drive shaft from Portland driveline which turned out to
be a disaster http://www.peachparts.com/shopforum/3502153-post16.html
A new one from Beyer was going to run almost $600

I ended up doing it myself using Diesel 911's thread found in post #8 above.

I got the old u-joint out and had a fabrication shop press in the new one
to the specs buried somewhere in Diesel911's thread.

They got it to within 3/1000 the of the centering spec.
Centering the ujoint precisely is important.
The ujoint is a GMB 220-7284
Part # 900 410 00 31 at a certain AZ parts place.

Hardly any shops have the 20K machine to stake in the u-joint and the
fabrication shop just welded in some washers to hold it all in place.
I have put about 6K on the drive shaft since and there is no vibration.
I inspected it a month after I put it in and all was good.
I plan to get under there and reinspect the center support and welds to make sure
all is well before a road trip next month.
Going down to Big Sur to photograph & go camping with a bunch of friends:-)

Jeff

Here's a photo of the tack weld the shop did for the ujoint retaining washers.

Jeff

Oops! I'd be leary of that.

I have seen some subaru owners do that and some BMW owners do that too. If the joint is centered correctly and locked in place everything works good.

Did they re-balance the Shaft after changing the U-joint and welding the Washers in place?

I'd be less worried if the washer was the right diameter.;)

The shop that pressed in the u-joint and welded in the washers
is not a driveline shop. After I had the work done I took it to
the only shop in town that can balance MB driveshafts and they
refused to check the balance as they did not do the work.
They wanted around $500 to put in the u-joint & balance.
I think it was around $100 to just balance, but they refused to do that.

After installing, I did the chalk balancing test myself and all seemed good.

I have done a number of road trips since then with no problems.
I plan to get under there this weekend and check things out.
I sprayed a light coat of paint on it before installing thinking if
there was any problem the paint would show cracking.

If the carrier bearing and u-joint don't show any cracks I feel
pretty comfortable with this. I don't feel any vibration and we have
a newly paved very smooth stretch of highway here.


Jeff