940 transmission vibration - prop shaft or differential?

[martin calva]

Originally Posted by 360beast

Propshaft vibration is most prominent when setting off from a standstill or when reaching certain speeds.

Did you ascertain whether or not your car has the updated strut rods and are the bushes for the front suspension in good condition? Also when was the tracking done? Are the front wheels balanced/buckled? All of those will affect vibration when braking.

My 940 is very susceptible to braking vibration if the wheel alignment is out, maybe it is to do with the polybushes but twice I've had the front suspension apart requiring a wheel alignment and both times before having the tracking done it got a bad braking vibration.

When they've got the car on ramps have they got the rear wheels hanging down or is it jacked up on the rear axle? If the wheels are hangin down this would put the propshaft at an extreme angle inducing a vibration.

Thank you for those comments.

[1] I asked about strut rods but (my French is only 75%) I did not get a clear answer. My guess is the strut rods are what was originally fitted to the car. The garage says all bushes are in good shape (they replaced bushes in the suspension triangle).

[2] Wheel alignment has not been checked as such. The April 2023 Controle Technique measured the misalignment/drift as negligible (drift = 2.9m /km)

[3] All wheels have recently fitted tyres which were balanced on fitting. The wheels are cast aluminium and are not visibly buckled. That will have been checked along at the C.T.

[4] Wheels are hanging down when on the lift. I'll ask them to try with the weight on the rear axle.

This is a problem that has appeared, getting progressively worse, since April. So something has deteriorated. I'll just mention again that the vibration on braking is a very severe and alarming juddering - not just merely a noticeable vibration.

Thank you again.
Martin