My 88 560SEC has only 32K miles but it had an annoying vibration that occurred around 25 mph under acceleration It feels like a washer machine with an unbalanced load during the spin cycle. The MB Mechanic that works on my car said he was 99.9% sure it was the drive shaft since everything else checked fine. After he replaced the drive shaft, with a new one that came in two separate pieces, the vibration decreased significantly but can now be felt at 15 mph. The vibration at 15 mph is slight under normal driving but if I press the gas and hold the car at 15 mph with the brakes or go up a steep hill the washer-machine-with-an-unbalanced-load-like vibration is easily felt. Cruising at 100 mph is no fun either since it feels like there is something out of balance somewhere. MB Mechanic said he will replace drive shaft again, this time with one that comes in a complete set instead of two separate pieces, since most likely drive shaft is still out of balance.

Since replacing the drive shaft changed the speed at which the vibration occurs, is it logical to assume the vibration is caused by the drive shaft or is there something else that could cause such a problem?

Thanks for your help.

I would say that the fact that there was a "real" change with the new shaft is a good indication that the problem is there.

MB has always placed great emphasis on not changing the relationship of the front to rear sections of the shaft. I have often wondered why they sell just the front and back halves. Buying a complete shaft assembled and balanced by MB should solve the problem.

Unfortunately, the other possibility is that you had two vibrations and only fixed one with the driveshaft. Your car doesn't have the miles to have problems with any of the joints, but I see as many half shaft vibrations as I do driveshaft vibrations.

Cars like yours that have sat for most of their lives can get some real weird problems.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Steve:

Thanks a lot for your reply. I will have the mechanic look into the half shafts also if the new driveshaft doesn't totally fix the vibration.

You are right about problems caused by the car sitting too long. I recently started to use it more frequently, at least twice a week for a minimun trip of 20 miles, because the weirdest things kept breaking from lack of use. Now the more I use it the better it seems to perform.