1985 300TD tight U-joint; replacement?

[54dan]

I've been noticing a driveline vibration above 45-ish mph in my 1985 300TD when there is no load on the driveline. That is, not accelerating or decelerating. I decided to replace both flex discs, the center carrier, and center bearing, figuring that's all good stuff to replace anyhow.

Today I pulled the driveshaft ... flex discs were pretty stiff and cracking, but not failing yet ... center bearing and carrier seems fine though carrier rubber is looking cracky. Hmmm... nothing obvious that would cause my vibration. Splines are in fine shape with no play.

I was figuring on just putting it back together with new parts to see what happened. Then, I noticed that the center u-joint is a little tight: no play but it feel like it could use some grease on both axes.

I suppose the right thing to do is get it to a driveshaft shop and have a new joint installed.

Any experience with having this done? Anyone have a source for a good driveshaft? Put it back together and worry about it later?

Having a great time with this car; really appreciate this forum.

-Dan

[connerm]

Dude, its the tires.

[piccolovic]

I would think you'd want tight U-joint. Did you replace that carrier bearing with the big rubber bushing? And I heard there's no one really set up in US to replace the U-joints. Easier to get another driveshaft from the junkyard.

Contact VSTECH about the ujoints. He'll tell you how to check.

[charmalu]

The U-Joints can be replaced. they are stacked in, so the stake has to be machined out.

I just had the 240 done about 6 weeks ago. the shop sent it to a machine shop, then they send it back, and he installs a Ford Mustang U-Joint with clips. Cost was $300, included the U-Joint, center support bearing and the 2 bushing in the end of the drive line where it fits over the centering pin on the Trans and Diff.

Good luck finding a good 28 plus year old driveline in the JY that is good. most all the W123 joints will have that notchy feel when bending the joint. the joint really doesn`t flex, with everything solidly mounted.

Charlie

[54dan]

Yep, it feels notchy when you move it. Tires are new. Thinking I may install new center bearing, carrier, and flex discs, reinstall and see what happens. On the other hand, hate to have it out and not replace the joint. Like you say, Charmalu, bet they're all like this.

Will report back ...

-Dan

[Diesel911]

This is what I did with mine.

My U-joint Repair thread 2011
Drive Shaft U-Joint Is Staked/Crimped In Place, Now What To Do? - PeachParts Mercedes ShopForum

My Benz World post with all of the U-joint sources.
Another U-Joint / Driveshaft Thread - Benzworld.org - Mercedes-Benz Discussion Forum

[charmalu]

When I pulled the shaft off, I check the flange on the Differential, nice and firm feel. different story at the transmission, the flange was loose and wobley. I removed the nut and pulled the flange. The nut had loosened up and/or the splines on the flange started to wear, and got worse and worse.

The splines have flat tapered sides and a flat top, these were worn to a point. the transmission splines looked good, being a hardened material.
so I swapped one from my spare transmission and used the nut from that trans. has to be staked after it is torqued down, and the old stake part was on the other side.

So between the loose U-Joint and the loose Flange, is real smooth now.

Charlie

[54dan]

So, I decided that I wasn't ready for this car to be down for an extended period while I tried to find a good driveshaft shop. I put it back together with new flex discs, a new center bearing and carrier, and a new rear trans mount.

I did check the trans flange and there was a tiny bit of play, but not much. In hindsight, I kind of wish I'd have maybe checked that closer for a loose nut...

The vibration is now all but gone. I thought I maybe felt it a little once at about 45 coasting.

I figure I'll hunt down a used shaft and see what I can do about getting a new joint installed on that instead of having the car down for so long ...

Thanks guys very much for the replies on this thread; I learned a lot!

-Dan

[rrgrassi]

I ended up replacing the entire drive shaft, with a re-man from a a good drive line shop.

[fdanielson]

Originally Posted by charmalu

I just had the 240 done about 6 weeks ago. the shop sent it to a machine shop, then they send it back, and he installs a Ford Mustang U-Joint with clips.

You wouldn't happen to know what Mustang U-Joint they put in there?