Diff knock?

[Chuckie]

Hi all I have a 1992 3b coupe and it has a knocking coming from the rear of the car when am on and off the accelerator at low speeds.
If I ride the clutch slightly and feed in the power it doesn't do it.
My garage has replaced all 3 rear diff mounts and the front propshaft c.v. Joint as these weren't in great condition and there was excessive play in the joint.
That all done it is still knocking. My garage suspect its the rear diff but can't be sure. I've had a mate have a listen and he too thinks it could well be the diff.

Just really wanted to know if anyone else has any ideas? Is it a common problem?
The cars done just over 112k miles and the fella I bought it off said it had previously had some 400hp race engine in it and can only assume he drove it hard. With launching with that kind of power would it soon cause issues, such as the diff wearing out??

This is my first s2, first turbo car and first Quattro so have thrown myself in at the deep end somewhat.

Any help or advise will be greatly appreciated as dont really want to be buying another diff until I know for sure.


Cheers, Dave.

[UrS4boy]

Could be excessive gear lash between the crown and pinion gears (Items 11 in the diagram below). Potentially possible to adjust this (with shims, diff on the bench).

[rynaqui]

Am soon having diff mounts on my S2 replaced, if these won't sort it, I'll start looking at the diff or possibly wheel bearings..

Good luck

[Chuckie]

Could be excessive gear lash between the crown and pinion gears (Items 11 in the diagram below). Potentially possible to adjust this (with shims, diff on the bench).

After having a good mechanic mate of mine have a look at it up on ramp it does appear to be excessive gear lash between the crown and pinion gears. He reckons its about 4mm! So I'm not messing about with having it apart.
Have got myself another diff that's covered only 34k genuine miles and will be having it fitted this weekend.
Will post the results of this once its done.

[Chuckie]

Okay so have now had the new diff fitted and has cured the problem, no more knocking!! So pleased.
Thanks again for the help UrS4boy.

[terrybullwon]

Did you bin the old one?

[Chuckie]

Na still got it, you interested?

[terrybullwon]

Yep!

[Chuckie]

Where abouts are you in the world? Will try and get some postage quotes but am away from tomorrow until Saturday morning so you will have to bare with me.