Loud knocking

Hey guys,

got a loud knocking noise coming from rear axle while rolling (in gear or out of gear). I had a look at the UJ and it looks fine to me, and had a wiggle of the wheels so I don't think it's the bearings. Also had a look at the diff oil level and that's full as well.

I can feel a bump every time it knocks, which I assume is the force just transferring up the radius arms. The knock seems more pronounced at low speeds, and hasn't effected the car's performance. In fact, it started before I left to Le Mans, so it's done more than 1.5k with the knock no problem.

The one thing I can say, is that under heavy breaking or rapid acceleration the noise does disappear. Makes me think the teeth on the diff are worn or something (or UJ, but like I say it looks ok to me)

She's a 1993 disco

Ideas?

Cheers

UJ or diff .. I've had broken UJ's that look fine, and don't move even with a small pry bar, but only 'cos they're so bad .. so take the prop off to check properly.

Diff, I had three teeth on the pinion ring let go, again, very very similar sounds and symptoms. Drove home from France with it banging and clunking, didn't want to leave it .. Only way to be sure, how I finally narrowed that one down to diff was to lift it fully, run it in gear, crawl under and listen to where the knocking was coming from .. best done on a proper 4-post lift!!

Even when the diff was out it was hard to see what was wrong till we fished in the oil and found the teeth!

could be a frame ball joint?

A frame joint first check.

knocking ? have you tried turning prop by hand while one wheel is jacked up