"Clunk" from rear of car. Back axle problem?

[martin calva]

My 940 suffered horrible alarming vibrations when braking from speed. The local garage changed many parts (front A-frame bushes, front hubs, prop shaft, UJ's, rear torque rod (or whatever they are called) bushes, a half shaft that displayed excess run out,...). But all without eliminating the vibrations. Eventually the garage owner said they should try replacing the rear axle. (On the grounds that they had replaced everything else so it had to be that.)

I made a long trip and came back with a 940 rear axle (marked as having the same ratio as mine) bought from someone with a scrap 940. Unlike my old axle there was no perceptible play when I twiddled the disk where the prop shaft would be attached.

The garage fitted the new axle. The story is confused because one of the front brake disks now had excessive run out, so still vibrations but now due to the front disk, which previously had measured as having negligible run out.. Once that was resolved there were no more vibrations when braking, so the months-long nightmare seemed to be over....

EXCEPT THAT: Now when I drive the car, when I put my foot down, there is a noticeable CLUNK from the rear of the car. Similarly when I lift my foot. It gives the impression that some part has not been bolted up properly or has large and excessive play.

The garage says they can find nothing that is not tightly bolted up and no slack bushes (just about all the relevant bushes have been replaced in any case).

The garage mechanic now surmises that the CLUNK is coming from inside the new (400,000 km) back axle.

My question: Is it possible to have a 940 back axle that seems to work fine and has no play on the inlet shaft, and none when the hubs are twiddled and yet gives a CLUNK when torque is abruptly applied or removed? If so, what can be done to correct the problem?

Many thanks for any advice.
Martin

[classicswede]

There should always be some free play.
I have had worn axle bearings (diff/pinion) knock every time you pressed the throttle or let off.
If it is only on harder throttle/lift off then that suggest torque rod bushes and it is common for them to do that

[martin calva]

Many thanks for this information.

The clunk happens on lightly pressing the throttle on or off. The torque rod bushes have just been replaced so probably not that.

Is it a thing to worry about? Or is it something that can be lived with for years to come?

Is replacing worm diff/pinion axle bearings a difficult job?

Martin

[classicswede]

The bearings are a axle specialist job

They can go on a long time but if the bearings are bad it can damage the CWP

Have they checked the oil level in the axle?

[mhuk]

Originally Posted by martin calva

Many thanks for this information.

The clunk happens on lightly pressing the throttle on or off. The torque rod bushes have just been replaced so probably not that.

Is it a thing to worry about? Or is it something that can be lived with for years to come?

Is replacing worm diff/pinion axle bearings a difficult job?

Martin

I had the same sort of noise and it was the large bushes on this. The diff was moving front and back and hitting the floor.