Is my problem a flex disc?
 

I have a vibration at around 40mph when i am accelerating through the gears. I am fairly certain that it is a flex disk. The harder I accelerate the worse the vibration. Will the rear one or the front one cause the most vibration. The reason I ask is the front one looks like new. Any advice greatly appreciated.

1993 190e 2.6 Auto 72k miles

Thanx!
Dan

Dan:

Usually the rear one lasts a lot longer than the front one (maybe due to higher temp in the front?). However, the vibration you mentioned could be from other sources as well (center bearing, differential, differential mounts, etc).

My mechanic mis-diagnose a slight clunk I had in my 1991 300E. After replacing the front flex disk, the clunk was still there. Finally he narrowed it down to the differential. Now I am using a heavier oil (Redline synthetic 80W140) and the clunk (along with a whine) is not noticeable.

A vibration at speed could be as was earlier suggested, the carrier bearing (center bearing), or something else in the differential. If the flex disk was bad enough to be vibrating like that, it would be about to let loose. Generally the front wears out before the rear.

To check the center bearing, you will need to open the bottom of the tunnel. Once the bottom plate is out of the way, you'll have a good view of the bearing and should easily be able to tell if the rubber has deteriorated.

I just looked at your car, almost 10 years and 72K miles, you might want to disconnect the front yoke at the flex disk, just to give the face of the disk a good look at. Check for any cracks in the rubber. If you see any, replace it - the disk is inexpensive but if it lets go at speed you will be in for a big surprise :eek:.

I do have a clunk in the diff. To verify I jacked the car with both rear wheels off the ground and and rotated each wheel in each direction and could get about 1/4" of play before the yoke on the diff would turn. It also whines. Will try a heavier weight gear oil as loubapache suggested as a cheap interim. Compared to live axle rear drive cars the diff noise on a MB is much more noticeable, Maybe cause the diff is bolted directly to the car instead of through shocks and springs?

Didn't check the center bearing as i didn't know it had one :) Still waiting for my cd-rom to arrive. Will check it this weekend.

I looked at the flex discs ealier. The front one looks like it's brand new. The rear one looks original. I am going to try and get the service records for it from the MB dealer today. That might answer a few questions. I've only had the car for about 2 weeks.

Thanx for all the suggestions, this forum is awesome!

Dan