Back end rumble. And clang!

[mishmosh]

My heralds minor rear rumble has suddenly escalated to a vibration snd louder rumble. Located in the centre rear of car. ( by diff. ) When setting off it’s started to “ clang “ as you change from 1st to second. I initially blamed the exhaust for the clang but now think it was the prop resonating. .  There appears to be no play in the prop ujs. However. There’s lots of play in the diff. And the ns output bearing feels worn.  Before I jacked it up I thought prop. But now I’m favouring diff. 
thoughts? 

[johny]

well possibly theres diff play if a pinon or crownwheel bearing has been poorly set up or worn a lot so the two gears move out of full engagement. This could then give a clang when taking up the play between the two - with both wheels locked the prop should have very little rotational movement.

What makes you think the diff output bearing is worn? 

[Clive]

It is tricky to feel the crownwheel/pinion backlash, it is always a tiny tiny amount. The rest is in the actual diff, usually worn washers. 

What type of prop is it? Solid, strap drive or even sliding joint?

[Pete Lewis]

output shaft bearing do wear out 

crown wheel and pinion backlash is only a few thousands of an inch  you wont detect this by turning the prop coupling 

if there  is some free  turn of the prop then is play in the actual differential gears as Clive says these wear 

if the output bearing has failed you can sometimes see this coupling  wagging around a little out of shape  when on a jack 

Pete

 

[johny]

Its just to get a clang I thought it would have to be play between pinion and crownwheel although if that were the case I wouldnt think the diff is going to last much longer😲

[mishmosh]

Thanks all for the replies. 

There appears to be a little play in the rear prop spider, so its off to Shelleys props for some love. Its a solid prop that was cut down to fit the overdrive 33 years ago and has been fine since, so its forgiven. Im now considering now having my spare diff reconned and swapping it over winter, as it was a good used one, i put on about 34 years ago....

[Clive]

In all hensty, I would get a brand new prop made. Just make sure they use quality UJs