Driveline vibration.

[PaulR]

I have a 94 Q45 that has a vibration/tremor between 45 and 65 mph.

It's coming from the driveline, which I verified by jacking the rear wheels. I removed the wheels and the vibration is still there. I then disconnected the half shafts, but that had no effect.

So, the problem is either coming from the driveshaft, diff unit or transmission (It doesn't happen in neutral).

I replaced the center carrier bearing a couple of years ago, and although the rubber has sagged a bit, I figured that, considering the weight of the driveshaft, that's to be expected.

I have removed the driveshaft and will take it somewhere for a balance check, but I don't understand whey a driveshaft, showing no signs of damage would go out of balance. I've had the car for 3 years, and it has always had this vibration, but it was never been as pronounced as it is now. Sometimes, the vibration was very minimal, and worse other times, which doesn't make much sense to me, unless it's just me being more sensitive at times to the conditions of the drive.

The Ujoint have no slack, although are looser in their working area than when rotated further than they would be while on the vehicle. Also, the rear suspension frame bushings need replacing, so there is movement of the frame over bumps and when torque is applied or removed.

The driveshaft is quite heavy, so I can see that any balance problem would have a big effect.

Has anyone had driveshaft balancing problems.

Thanks