Hi, Ive noticed a thumping eminating from the hump when I hit bumps, accelarate too hard in reverse, and de-accelerate at higher speeds (no braking, just fast off the peddle) I checked the exhaust and universals and they apprear to be fine. Does the center bearing on the shaft suppose to be loose enough to move it around 1/2 to 1 inch by hand or is that normal? If that is the culprit, since the u-joints are ok (105k) should I do them anyway or do they usually last longer w/ moderate driving? By the way, the 93 240 is an auto.

Thx Art

Sounds like U-joints to me. When my center bearing went, it moaned. When the U-joints go, they mess up driveline alignment by resisting angular motion... resulting in the thumps and knocks.

If you remove the driveshaft, note that there are alignment marks on the 2 halves. Reassemble aligned! Even one tooth off buys you the magic finger massage. DAMHIK.

I've found that the rubber collar part of the center support bearing shrinks a bit with age and allows an otherwise okay drive shaft to thump under the tunnel area when going over bumps. My fix is to loosen the support mounting bolts, insert a rubber spacer above the support bracket (like the seal ring from a used oil filter cut open) and re-tighten. Your problem could also be related to bad engine mounts or worn trailing arm bushings.