Another W126 Driveshaft Question
 

I'm getting a vibration at 60+ mph. The flex disks and universal joint are OK. I can shake the driveshaft assembly about 1/4 inch back and forth at the center support, and I guess this is due to the rubber mount surrounding the bearing.

There seems to be some play between the front and rear driveshaft halves. When I turn it back and forth or shake it, there is a metallic ringing noise that seems to come from the front half. Is this a likely problem?

It could be the center support bearing. I had a shake at about 45, their was just a slight amount of side to side play if you grabbed it and tried to move it.

The center bearing support is rubber and was worn, I also replaced the bearing itself. Now no play really, just a little movement because it is rubber mounted.

The drive shaft is in two parts, their is a spline that mates the two halfs together. I don't see how that could wear. Well at least mine at 250k looked like new and was tight as can be.

I'd recomend removal and inspection, maybe bring it to a driveshaft shop for a balance and see what they come up with.

The manual says to remove the exhaust system to remove the driveshaft. I am VERY afraid to move the cat since it is fragile but still works. But I can't get at that big 4x mm nut otherwise. No shortcuts, I suppose?

how is it that you are
 

sure that the flex plates are fine? i dont see how the ds would have play in it without haveing a huge vibration. i would take another look at the flex joints, i think.

tom w

The flex disks are solid with no cracks and no movement between the drive and driven sides. I'm wondering if I can remove the shaft and center bearing, carefully measure the length between the 2 halves, then reassemble without having to access the spline nut once its installed. The center support is right above the cat, which I don't want to disturb.

I don't know whats under your car, on the SDL you don't have to touch the exhuast. I am sure the V8's are different.