I have a drivetrain vibration under load. I have replaced the ujoint and the carrier bearing. It seems like an out of balance drive shaft but it only occurs under load 55-65 mph the worst. Going up hill or accelerating worse. Going downhill disappears completely with no load. Put car on hoist and removed back tires vib there at same speed reading on speedo. Any ideas from one of you MB pros. Put a new half shaft on a year ago. I noticed no galling in ring or pinion and vib stayed the same. Could it be a bearing in the rear of the tranny or front bearing in the diff. can't feel any play. This has been doing this for 20,000 miles. Doesn't get worse just an aggrivation. I don't drive the car enough to spend big bucks fixing. Any ideas from some MB mechanic or owner who had similar problem.

I had a similar problem in my '83 300. I had three different driveshafts in the car, the vibration was the same. It would occur from 40-45 MPH under load. A full tank of fuel would lessen it, as would weight in the trunk.

Fast forward, I just had CVJ reboot my original axles, which were still in good shape. I reversed them left to right on the install to wear the other side of the spiders. The vibration is gone, and is now felt slightly on deceleration, so I know it was the axles. There must be a little wear in one of the joints and since they're three-lobed and we have a 3.07 axle ratio, the frequency would be indistinguishable from a DS vibration.

When you say you replaced the U-joint, did you have a replacement staked into place? Or did you have the yoke cutoff and have a yoke re-installed with a replaceable joint? Also, have you replaced the front and rear rubber flexjoints that attach the driveshaft to the tail end of the tranny and pinion yoke on the diff? When those get old and weak, they can loosen up under strain even if the threads aren't showing through yet, which more rotation under load exacerbates.

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1987 300SDL #1, 1987 300SDL #2, 1980 240D, 1982 300SD, 1994 S350, 1990 350SDL, 1991 350SD, 1985 300D, 2005 E320CDI

Gone, but not forgotten: 1981 300SD, 1982 300SD, 1987 300SDL, 1983 300TD, 1980 300CD, 1981 300SD #2, 1987 300D, 1987 300TDT, 1980 300D

I looked in the below thread but there is no details on the Job.
u-joint for 85 300CDT

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84 300D, 82 Volvo 244Gl Diesel

In the event that you have not already done so, have a look at the engine mounts. The felt vibration is, in part, torque sensitive. On deceleration, the torque reversal will lift a defective engine mount out of contact with the chassis.

Sounds like worn cv or two to me.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Vibration under load. Check you valve clearances. A too tight valve can cause a strange vibration that will only be felt under load. I speak from experience. In desperation I went so far as to pull the trani to inspect the torque disk.

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1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

Oh boy, one of those kind of problems! I had the new ujoint staked in. Vibration was the same before and after install. I'll try replacing flex joints when I get to it. Try one thing at a time til we hit the solution. May take a year but will keep you posted. I adjusted the valves when I bought the car. They where in spec.

You still never said exactly what you did to fix the U-joint?

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84 300D, 82 Volvo 244Gl Diesel

put a new one in, don't know of any other way to fix a bad ujoint. Put a run out gauge on the shaft, it's not running eccentric. The old joint was bad but the vibration didn't change at all with the new one in.

So it had the same vibration before you changed the U-Joint?

Simply saying you replaced the U-joint does not hardly explains everthing since the Driveshaft was not made to replace the U-joint.

As an example I know when I replaced My U-joint the Bearing Caps on are spaced out a little further out than they should be because I did not find the spacing information until after the U-joint was installed.

The U-joint I used could have a different Bearing Cap spacing from another companies.


Then the Caps need to be spaced equally from the Center of the U-joint.

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84 300D, 82 Volvo 244Gl Diesel