'81 driveline collar loose. still need to replace bearing?
 

hello

http://i650.photobucket.com/albums/u...IMGP0063-1.jpg
http://i650.photobucket.com/albums/u...IMGP0064-1.jpg
http://i650.photobucket.com/albums/u...y/IMGP0060.jpg

on my '81 300 SD TD I have had a bad vibration (much more than a harmonic, i can feel it in the car seat) that occurs at about 25 and 35 mph. Pressing the accelerator makes the vibration (more like a fast thumping) more pronounced. When up on a rack, vehicle running and in gear, i could see the driveline moving around behind the front flex plate. By moving around, i mean i put my finger "riding" on the shaft as it spins, and my finger goes back and forth; pronounced out-of-round.

I dropped the exhaust and shield, some rubber pieces fell out, must be the "rubber dust shield" talked about in this article http://www.peachparts.com/shopforum/tech-help/53817-how-replace-center-bearing-support-flex-discs-w126-3-0-a.html

in moving the driveline around, I think the bearing is good, the rubber is still good around the bearing, i can move the driveline around with force and the rubber gives. there is slight play in the two shafts at the u-joint (twisting each different directions it has a very small amount of play) is that bad?

the big "flag" to me, is the metal collar holding the two drivelines together at the splines just in front of the carrier bearing, is totally loose; it spun with a flick of a finger.

at this point:

do i need to replace the dust-shield (maybe comes in a bearing set?)
do i need to replace the u-joint?
do i need to get the driveline balanced?

all the above?

or maybe i need to tighten the "collar" and test drive it???

thanks everyone

Guy

The nut should be tight. there is a dust boot that covers the splines. yours looks petrified.
The U-joint should be snug w/o any loosness in it. they do become notchy when bending them. I have seen this on lots of MB.

If it is wobbling around, and you see it at the front flex disc, then might be a good idea to replace it also, along with the center support bearing.

If you see and feel the loosness in the u-joint, then it is time to have it replaced. they are staked in, and are not a DIY job.

I had mine replaced on the 85 300D. the shop replaced the center support bearing, and replaced the u-joint with a greaseable one that is used in a lot of Fords. YEP. got a Ford part on the ole MB.

they charged me $256.00.

Here is a shop that does MB drivelines in Portland. not all shops can do them.

Driveline Service - Mercedes Driveshafts


Having the car upn a lift with the driveline turning, you would be in a heap of hurt if it should grab a piece of clothing, hair, neck tie etc...;
Charlie

as always, thanks so much Charlie.

I do know we spoke of this before; now that I knew a little more I wanted to put it out there. I see that Portland's seems to be the shop to do it. I know there are a couple competent DL shops here in Eugene, perhaps they won't even touch MB's (or Lexus or BMW).

sure sounds like i just need to do it all since it's down. Thing is, the flex disks look spanking new. So does the carrier bearing. Maybe the person changed those, and not the dust cap or the u-joint, hoping that would fix it, when it is actually the u-joint (trying to save money just to sell the car).

surely when i get it to the shop, they'll tell me, since doing all including a balance would sure be a peace of mind.

I have a call into them today, maybe they just have one ready to go as an exchange even.

any other thoughts?

Guy

let us know if the shop actually CAN change the u-joint... the general consensus so far is if the u-joint is bad, you replace the DRIVESHAFT!!! MB did not make them replaceable for the normal tech...

oh boy. In the link Charlie gave, they have a great picture and description of what they do, so it looks like they can.

Driveline Service - Driveshaft Specialists


I'll keep you posted...

UPDATE:

well one shop in Eugene won't do it, just sell a new DL for $380

the portland shop won't do it, $450 for a new DL $75 for a core

There is another shop in Eugene, it's known mostly as a truck shop. I've used them for drivelines in the past:

He could switch out for one that would closely fit, weld in some washers in the ends, after perfectly aligning the two shafts while the u-joint is in place while on his balancing machine.

he also suggested going to a straight shaft, he could possibly weld up a bracket in the front before the flex disk for a u-joint. He did this once on a 2" DL (not sure, that may have been on a BMW i forget what he said). Also once for a gentlemen that pulled in with a vintage Benz, he said "looked like a cross between an old New York taxi and a Mercedes" (haha). He told the guy he didn't work on those. he said "watch this" pulled a lever, roasted both back tires. He had a ford 9" rear behind a 350 chevy. said it almost bolted right in. manifold fit perfectly, only had to slot out the transmission mount a little, then of course make a A&B wiring setup for the distributor and rectifier. He worked this up for him.

He told me I need a V-8 (ouch) I guess there is that '69 mopar 318 sitting in my garage....

could be a $200 fix. precise measurements of course with flex-disks in place.