Vibration

[shoe]

On my 83 300D turbo.
What kind and how severe of a vibration would a loose rear wheel bearing have. I have a high frequency vibration that comes in about 35 to40 mph and gets really bad about 60 to 65 mph then decreases after 70 mph. I thought that I might have an out of round tire, but I can't find any slipped belts. Could a flex disc cause this. After about 60 miles of highway driving it will get so bad that I can hear the exhaust banging something. There has been a slight bit of slack in the right rear wheel bearing since I have had the car. I never had it replaced because it never made any noise. The axle boots are not leaking so I assume the CV joints are ok. I need to find this problem, mywife is getting afraid to drive it.

[Stan Pittman]

Check the center support bearing and ujoint. Usually you should remove the entire driveshaft to check the center ujoint.

Shoe,

I had a bothersome vibration on my '85 300CD (142K miles) that about drove me nuts. Tried everything to correct it to include balancing main drive shaft, new flex discs, new engine mounts, etc. Finally replaced half-axles and that solved it. Mine weren't leaking oil but something was wrong with them.

Apparently, vibration can be caused by many things and trouble shooting is hit or miss. I took my car to any number of shops (including Mercedes dealer) without success.

Good luck,

Nic

[shoe]

Thanks for the input. I have not brought it to a shop yet. I want to check what I can before I do. I plan to bring it to work and put it on the rack and remove the drive shaft. Can anyone tell me what to look for in the flex disks as far as wear and tear. I am used to u-joints. and hanger bearings. I assume that I should look for tears, but is there anything else? On the half shafts I plan to do that as a last resort.

[JimSmith]

Shoe

I have had the center support bearing go bad, and the CV joints in the half shafts on the rear axle go bad over the years on 240D's. They made distinctly different noises, but in both cases you could find a speed and load (how much throttle you give it) condition where the noises would subside.

The center support bearing was a distinctly bearing type of noise, whirring, groaning, droning and the like. It tracked with speed in terms of loudness and tone and seemed to be coming from the driveshaft tunnel. The CV joint noises were much more alarming and also tracked with speed but were not coming from the driveshaft tunnel. Open the window and listen, or have a back seat passenger listen with the rear window open.

Once under the car the condition of the driveshaft center support bearing was visually apparent, the rubber do-nut it sits in was shot and you coud see the races. With the CV joints, there was a low speed, "crackling" type of noise coming when the car was rolled along the street that was clearly coming from the half shaft area. Grabbing the half shaft on one side and jerking it around compared to the other side showed some extra movement. I may have worn the machine more than most, but I was on a 600 mile trip and drove home with the noise, trying to hold the speed and load where the noise was least noticeable. Upon close inspection the boot showed a small tear also and that is the apparent cause of failure of the insides.

Jim