Trying to diagnose bad driveshaft center bearing - PeachParts Mercedes-Benz Forum

1983 300TD · #1 10-23-2005, 03:54 PM

This post is in regard to a 1983 300TD wagon, with 322,000 miles. The car is still running strong.

Last week, I heard what were "classic" halfshaft gone bad noises from the rear. I replaced the passenger side halfshaft less than a year ago, and it still looks good. The driver's side halfshaft had dry rot on the boots, so that got replaced this past Friday. When I drained the differential, all looked fine and normal, no metal shaving/particles in the drained fluid.

After putting it all back together, the noises persist. What is strange, the noises range from clicking, to a almost metal on metal grind, to a whir. The noises are most noted at slower speeds; while speeding up, and while slowing down. At 55-60mph, it almost sounds normal, but with a 'snow tires' on dry pavement type sound. My research here indicates that it is more than likely the driveshaft center bearing. Is there anyway I can tell for certain? I got under the car to inspect it, and it seemed to look fine, but I don't really know what to look for. Is this an item that would normally need to be replaced on a car with such high mileage? Aside from the halfshafts, is there anything else that it could be? Both the front and rear flex plates look really good, incidently. No dry rot, no cracks.

Also, what do the 8mm and 12mm refer to when buying a halfshaft? I bought an 8mm last year, and got another last week for the driver's side. It's bugging me that I cant' remember what that references. Thanks to all.
Damon

t walgamuth · #2 10-23-2005, 05:46 PM

but i would grab the ds next to the center bearing and shake really hard. if it wiggles it is bad. if good it should give only as much as rubber will give. not much at all.

tom w

1983 300TD · #3 10-23-2005, 06:04 PM

thank you for the reply.

i shook the center bearing and it did seem to have some play. how rigid are we talking here?

Maki · #4 10-23-2005, 06:37 PM

I got a variety of clunky/whiny/clicky/grinding noises awhile back when the linings delaminated from the parking brake shoes.

I had a center driveshaft bearing go dry once on an Audi. It made a noise you wouldn't forget, like a warbling banshee. Of course, if the center bearing carrier has torn, the shaft will want to bang against the driveshaft tunnel, especially when accelerating. At least, that's what I've read. I've never experienced that failure myself...

engatwork · #5 10-23-2005, 07:00 PM

Here is a shot of one that I have recommended to a "customer" that he replace over the next 4 weeks. You would not believe the knocking noise this one makes during hard acceleration, right hand turns. It is noisy as all get out.

If you look closely at the pic you can see my gloved finger throught he gap of the support. I have recommended sending it to Driveline Service of Atlanta for a complete rebuild.

1983 300TD · #6 10-23-2005, 07:15 PM

[QUOTE=Maki]I got a variety of clunky/whiny/clicky/grinding noises awhile back when the linings delaminated from the parking brake shoes.

Wow. Interesting take on this problem. My parking brake has not worked for years, and the brakes in the rear are very close to needing new pads (lots of wear). When you say the linings delaminated from the shoes, what do you mean? Just try to explain this like you're explaining it to a child.

Thanks.

I guess this especially caught my attention because at times the car almost feels like it's forward movement is being impeded by this problem. So a possible brake hang up would kind of make sense. I do know that both rear calipers are working properly and not hung/frooze up.

t walgamuth · #7 10-23-2005, 08:03 PM

means that the brake lining material has separated from the metal backing plate and is free to wander around back there doing whatever wild and crazy things it wants instead of only doing your bidding.

tom w

1983 300TD · #8 10-23-2005, 09:09 PM

Quote:

Originally Posted by t walgamuth

means that the brake lining material has separated from the metal backing plate and is free to wander around back there doing whatever wild and crazy things it wants instead of only doing your bidding.

tom w

would I be able to tell if this has happened by simply removing the tire, or do I need to remove the caliper? Or is it remove the caliper, than the rotor, and look inside?

Hatterasguy · #9 10-23-2005, 09:12 PM

My W126 had a very noticable driveshaft vibration from 45-55. Today I pulled the driveshaft and upon inspection I found the bearing to be a little dry and the rubber support to be off center. I will know if that was the problem in a few days I am just waiting on a few parts.

Maki · #10 10-24-2005, 01:17 AM

Quote:

Originally Posted by 1983 300TD

would I be able to tell if this has happened by simply removing the tire, or do I need to remove the caliper? Or is it remove the caliper, than the rotor, and look inside?

You'll have to pull the rotor (and caliper, to get it out of the way), to be sure. And you may need a rubber mallet to persuade the rotor off. You can back off the parking brake shoes to make rotor removal a little easier if you can line up the star adjuster wheel through one of the lug bolt holes in the rotor hat.

Rather than try to describe the procedure, here's a page from the repair manual:
http://skinnerbox.steaky.org/service/W123/w123CD2/Program/Maintenance/MY81/4261.pdf

HTH

cornblatt · #11 10-24-2005, 10:30 AM

Quote:

Originally Posted by 1983 300TD

My research here indicates that it is more than likely the driveshaft center bearing. Is there anyway I can tell for certain?

If the bearing is bad, the noise/vibrations/scraping/friction will transfer from the bearing to the part of the car that the bearing is mounted to. So, get someone else to drive the car. Ride in the back seat and put your ear down over top of the hump in the center of the floor. If the noise is loudest right over that point (the bearing mounts right beneath there), then that's your problem. If it is the center support bearing, it will be very obvious when you listen up close like this... I've had to replace this bearing twice, so I'm familiar with the sound. Cold weather / cold driveline should make the noise more apparent. If, after doing that, it's still not clear where the noise is coming from, then keep looking...

If the bearing or rubber support are obviously damaged looking, then you know you need to replace them, but keep in mind that they can look perfectly fine and still make a lot of noise. The bearing is not very well protected, and once water and road grit make their way inside, it doesn't take long for it to go bad.

autozen · #12 10-24-2005, 10:53 AM

The bolt that holds the axle in the hub was 12mm on earlier models and 8mm on later models. The 3 keys to replacing the axles properly are:Use the differential shim from the old axle. Use the tube type hub spacer from the old axle. Don't tighten the hub bolt too tight. It has a light torque.

1983 300TD · #13 10-24-2005, 02:53 PM

o.k. While checking the driver's side rear brake assembly for the delaminated parking brake, I think I found the real problem. I took the wheel, caliper, and rotor all off. No parking brake shoes at all, everything was removed evidently years ago. Guess that explains why my parking brake doesn't work. Anyway, I spun the wheel hub and found the noise. So I believe the actual diagnosis is a terribly bad rear wheel bearing.

Problem is, after reading about replacing the rear wheel bearing, I don't know if I should be glad that it's not the center driveshaft bearing. It almost sounds like that would have been easier? I don't know. So here's my thought, which is probably ridiculous and idealistic. Is there such a thing as buying a rebuilt rear hub assembly, as opposed to replacing the bearing. You know, 'let someone else do it because I don't want to' type thing.

If not, can I just remove the hub and take it to someone for repair? Thanks for you help.

autozen · #14 10-24-2005, 10:10 PM

You really need a special tool to remove that hub. You might want to have it professionally done.