Speed Related Vibration
 

On the '84 300D Turbo there is a slight vibration that I AT FIRST thought was RPM related. However, between 30-40 mph the vibration occurs even in neutral. Tire/wheel balance? Brake rotor/pad/caliper? Flex disk? The reason I mention the latter is the vibration appears to be emanating from somewhere central of the chassis. Additionally, it is felt and heard in the shifter. The fact that it persists while coasting in neutral has me perplexed. :confused:

Flex disk or driveshaft carrier bearing. There's been lots posted on that part, so a search should bring up some good info.

I'd go along with the flex disc, but I've never seen a carrier bearing cause the vibration you describe. I'd do a visual of the underside of the car,and check the tires for ply separation and age. If I couldn't find anything, I'd remove the rear section of the drive line and check the cardon joint for smooth movement in both directions. Remember to mark the two pieces.

Peter

I think your first, and least expensive, guess would be the best place to start. Check your tires for balance first. I had a mystery vibration and after searching the drive train and finding nothing. It turned up as a tire with belts starting to separate.

I have the exact same symptoms and my carrier bearing rubber is bad. I jacked up the rear of the car and had someone run it. Amazing how much vibration the shaft makes with bad rubber.

I'd go along with tires first-easiest to check.

My next guess would also be the center support bearing or driveshaft carrier bearing as some are calling it.

If the rubber on the bearing is shot it needs changing anyway. ;)

Cheers,

Bill