Weird under the seat vibration + noise ...

[Bruno]

on a 633 csi, complaint of vibration right above 60km/hr (37 mph).
Nasty noise like if you were driving on very bad road.

The rear diff mount was ripping appart the body so we welded that in place.
Still the weird noise.

The center bearing is shot and the driveshaft was moving around (no vabration below 37mph). I am in the process of changing it.

Could it be a bad wheel?? Could it be driveshaft that need to be balanced?

This is a weird one as the car is perfect below 37 mph. as soon as you hit 37 mph and above, you have a bad noise from the back...
As soon as you go right below 37mph everything is perfect again....

Any clues?

[western99]

on a 633 csi, complaint of vibration right above 60km/hr (37 mph).
Nasty noise like if you were driving on very bad road.

The rear diff mount was ripping appart the body so we welded that in place.
Still the weird noise.

The center bearing is shot and the driveshaft was moving around (no vabration below 37mph). I am in the process of changing it.

Could it be a bad wheel?? Could it be driveshaft that need to be balanced?

This is a weird one as the car is perfect below 37 mph. as soon as you hit 37 mph and above, you have a bad noise from the back...
As soon as you go right below 37mph everything is perfect again....

Any clues?

[tim]

I saw a problem like that once on a modified 540. It had huge rubber on the rears, like 18's, and the camber modified. When it got above 40mph it shook so bad it would knock your fillings out. We never figued it out, but it went away when we changed out the wheels, and reset the stock camber settings.

ps, this one blew out its center bearing also, so I would think its as a result of the problem rather than the cause.

[632 Regal]

prob just the center bearing causing all the problems

[Bruno]

prob just the center bearing causing all the problems

All the center bearings problem I have seen on the 5 series were giving vibrations and knocking on 1st gear then it was smooth...

I wonder about rear wheel bearings and maybe diff pinion bearing...

How do you check the pinion bearing on the diff???

[632 Regal]

with the wheels and brakes removed. You want to feel for a bit of preload before the axle shafts spin, appx .06 play between the gears and should be silky smooth.