1983 240D U-joint. How notchy is too notchy? - PeachParts Mercedes-Benz Forum

trout007 · #1 01-01-2016, 08:34 PM

I'm doing a flex disc and centerline refurb and my U-joint feels notchy. How much is too much? I was having a vibration in the 45-55 mph range. Could this be the issue? The U-joint bearings are staked in. I've seen some old threads about cutting the stakes and replacing the bearing. Has anyone had long term luck? What are my options?

Also in the FSM it shows a clip holding in the center bearing dust cap. I don't have on e that I can see on mine. Is that typical? Do I just pry off the cap?

vstech · #2 01-01-2016, 10:23 PM

Every u joint I've seen was stiff in one place... As long as there is no play, I wouldn't worry about it.

trout007 · #3 01-01-2016, 10:41 PM

Thanks vstech. What about the circle clip? Is that supposed to be on the 240D?

Stretch · #4 01-02-2016, 06:14 AM

A notchy UJ could be the source of your vibration. The trick is to get the output of the transmission in line with the propshaft centre bearing and that in line with the input of the differential. PlaneCrazy over on BW has recently been playing with this =>

What did you do to your W123 in 2015? - Page 58 - Mercedes-Benz Forum

trout007 · #5 01-02-2016, 08:59 AM

Thanks Stretch.

So as I understand it I put the new Centerline Bearing and Carrier on. Put the new Flex Discs on and get the DS into the car. Fasten the Flex Discs to the Transmission and Differential. Then screw in but don't tighten the bolts for the Carrier. Also leave the 46mm nut on the shaft loose. Then drop the car and roll it back and forth and bounce it and roll it back and forth again. Then finally without lifting the car sneak under it and tighten the Carrier bolts and the 46mm nut.

Should I try the DS alignment that PlaneCrazy is doing or is the rolling and shaking in place of that?

Stretch · #6 01-02-2016, 09:18 AM

Quote:

Originally Posted by trout007

Thanks Stretch.

So as I understand it I put the new Centerline Bearing and Carrier on. Put the new Flex Discs on and get the DS into the car. Fasten the Flex Discs to the Transmission and Differential. Then screw in but don't tighten the bolts for the Carrier. Also leave the 46mm nut on the shaft loose. Then drop the car and roll it back and forth and bounce it and roll it back and forth again. Then finally without lifting the car sneak under it and tighten the Carrier bolts and the 46mm nut.

Should I try the DS alignment that PlaneCrazy is doing or is the rolling and shaking in place of that?

If I were you I would cross my fingers and hope that the parts are aligned properly after doing the rolling backwards and forwards trick (which by the way should not be attributed to me - I just read about it on this forum and have found that it helps in many cases)

If after doing this trick you still get drive line vibration then I'd start doing the measurements like PlaneCrazy has been doing to see which bits are not at the ideal height.

vtmbz · #7 01-02-2016, 10:53 AM

I'm with Vstech. I've never had a u joint that was not notchy. I'm of the opinion that the center bearing needs the most maintenance and attention. I'm also careful to mark the two halves of the d.s. In relation to one another during removal.

Diesel911 · #8 01-02-2016, 11:09 AM

If it is not causing an issue then I would not worry about it.

I did not review this thread again but I think this is the thread where it tells you how to free up the U-joint.

Sticking U-joint causes Vibration that Rips up several Drive Shaft Supports turns out to be Rusty Needle Bearings
http://www.peachparts.com/shopforum/diesel-discussion/338641-w123-propeller-shaft-vibration-tears-up-rubber-mounts-replaced-nearly-everything-3.html

I replaced the U-joint in mine and had no issues with it after replacing it even though I did no re-balancing.

My U-joint Repair thread 2011
http://www.peachparts.com/shopforum/showthread.php?t=293976
My Benz World post with all of the U-joint sources.
http://www.benzworld.org/forums/w123-e-ce-d-cd-td/1581728-another-u-joint-driveshaft-thread.html#post4677977

Anyway you have a few choices.

yuke · #9 01-02-2016, 11:11 AM

I had that notchy feeling in my u-joint had very bad vibration at high speed so I went thru everything new center bearing, flex joints, u-joint, and front half of this the D.S. as somehow the bolt holes on the balancer damper on front driveshaft wore oblong I think because bolts loosened up from all the vibration I think tnis was the main problem if I had to do it again I would have left the notchy u-joint in when I replaced it I had a friend tack weld the joint in place in stead of restackeing or peaning it. The driveline is vibration free ever since.

trout007 · #10 01-02-2016, 01:28 PM

Thanks everyone. This forum is wonderful. I'll try the rolling back and forth first and report back.

trout007 · #11 01-03-2016, 03:34 PM

One question on the washers for the flex discs. It looks like they always go on the disc side, not flange side. So 3 are under the heads of the bolts and 3 are under the nuts. Is that correct?

vstech · #12 01-03-2016, 05:04 PM

Quote:

Originally Posted by trout007

One question on the washers for the flex discs. It looks like they always go on the disc side, not flange side. So 4 are under the heads of the bolts and 3 are under the nuts. Is that correct?

Yes.

86-300sdl · #13 01-04-2016, 09:25 AM

I had the 45mph to 55mph drive line vibration. Notched drive shaft. Replaced trans mount, diff mount, and flex disks. No change. Ultimately had to have the drive shaft u-joint replaced and shaft balanced. About $300.

However I did get a lot of vibration relief for many miles i.e. 20,000 with changing the shaft angle thus u-joint pivot point (to an un-notched position) by adding washers to the center bearing carrier between the carrier and the car body which lowers the shaft plane slightly.

vtmbz · #14 01-04-2016, 10:04 AM

THat sounds like a great test for "too notchy"! CHeap and easy with immediate feedback. How many washers did it require to move to another angle?

Stretch · #15 01-04-2016, 10:43 AM

Quote:

Originally Posted by vtmbz

THat sounds like a great test for "too notchy"! CHeap and easy with immediate feedback. How many washers did it require to move to another angle?

There isn't going to be a magic number or thickness of washers if they are needed. If you look at the BW post I linked earlier in the thread showing what PlaneCrazy was doing to his W123 then you can see the method used to get the idea of if or where a centre bearing mount might need padding. PlaneCrazy is using taught string between two points on the car whereas I've checked relative heights on a nice flat surface / driveway.