Vibration at 50mph while accelerating.
 

Hello all. This is my first post on any forum so please bear with me. The car is an 84 300D turbo with 209,000 miles. I get a droning in and out vibration at 50mph, but only while accelerating. I feel it in the floor, seat and steering wheel. I have replaced the CV axles, center support and bearing. This did not help at all. All inputs would be greatly appreciated. Thank You.

Did you aligned the wheels balance?

Check the flex discs on the propshaft.

As an experiment, Loosen one of the bolts that hold the carrier bearing to the body and remove the other. Put a washer between the carrier and the body so that you can put the bolt that you removed back through it.

See if this helps. This will put the u-joint in a SLIGHTLY different position away from the "notch" that normally wears into it.

While under there check to see that all motor, transmission and differential mounts are tight. You may need to pry around with a long bar to check them.

If its kind of a tuning fork vibration at those speeds, I have it as well. It goes away as I speed up. I have about the same mileage and the flex disks were never replaced. I plan to change mine since some people say its a maintenance item anyway.

check your motor mounts they sound as though they are flat and we all know that to drive a diesel "first put your foot to floor" this causes engine to torque over and if mount is failing you get engine vibrations through the car.

Thanks to all who replied. :) The wheels have been aligned and balanced. As far as I can tell the flex discs look okay, they are not cracked or deformed. I plan to replace them this spring. I really like that idea of using washers to change the alignment for the u-joints. Thanks Larry. David, It's funny you should mention motor mounts because I was kind of thinking the same thing. That is the first thing on my list to fix this problem. They will be here in a few days. I have owned this car for about a 1 1/2 years and I put about 60,000 miles on it. I absolutely love it. I just need it to stop vibrating.