90TD driveline knocking???

My Wifes 90 TD (LT77) has developed a strange knocking/thudding coming from the driveline.
When travelling at reasonable speed, say 40+ its really evident and seems to be coming from the rear. It's a strange thudding that isn't rythmic - ooerrr..
If you let the 90 coast and put it in neutral, it's still there and really evident as it slows down.
I've changed all the gearbox and diff oils & greased the propshafts. There is a very small amount of play in the propshafts and the diff pinion has about 45 degrees of freeplay.

I suspect the rear propshaft, or diff, but i suppose it could be the transfer box. I'm reluctant to spend cash until i've narrowed it down a bit.

Has anyone seen/heard/experienced anything like this before?
Any tips on troubleshooting welcome too!

could be the uj they are prone to going and making a knocking noise

try looking at the rear a-fram ball joint....mine has a tendancy to work itself loose at times cos of the travle its got and the punnishment it gets,but they have the tendancy to do it anyhows
to test chock the wheels...let handbreak off...get underneath and turn the hand break drum quickly back and forth (violently) so it makes a loud clunk noise and whatch the nose of the pinion to see if the axle is moving up and down
danny

Great info guys. Thanks alot....

Keep 'em coming people....

to eliminate the prop ... take it of and take it for a spin with out it on, but dont forget to engage difflock as u wont get very far
could be you diff cabbaged or trailing arms bushes worn
u definately sure its the back end ??
danny

I'm as sure as i can be it's at the rear, but noises travel so it could be from anywhere.
Strangely, the noise isn't travelling up the steering column, which is why i'm more drawn to the fact it's coming from the rear.

I may have to remove rear prop and take it for a spin.....

check the ball join, if thats a no go'er
take the prop of and give her a whirl
then report back with findings, to give me another brain tickler
it alot harder to fix them over a computer screen than bein under the damn thing lol
danny

Thanks Danny.... great stuff.
I'm hoping for cheapo ball joint obviously...

SWMBO is in for a shock if it's the diff

diffs are cheap enough tho

BUT ... if it wtas me and it is the diff....get a good second hand one and say you had to get a recon one and ask her for the money .... recon 135 quid...2nd hand 30 ish hehe but i didnt say that
anyhows try that and then give me a bell if there no change and ill advise on a few other things that can cause your problem
btw do you no anything about getting sectioned ??little nay sed it to me ??
danny

Well, i've checked the Balljoint - that's OK
I've removed the rear propshaft and taken it for a spin, and the noise/thud is still there.
It still seems to be coming from the rear, but sound travels so it might not be.

I guess the next steps are: -

1) remove the rear half shaft aswell & take it for a spin.
2) if noise is still there, restore rear driveline and remove front prop, then take for a spin...

I guess if the noise is still there after that, it must be the T/box or G/Box....

remove rear h/s and leave prop off and take it for a spin...if no noise its the diff

when checking the front end over
check the output shaft bearing for play on the transfer box as that missleads you when it gives up
danny

I've removed the rear halfshafts and taken it for a spin. The knocking/thudding doesn't start until everything has warmed up so i think that rules out any suspension components. But, it did start again, and more than ever sounds like its coming from the rear.
When i got home i lifted each rear wheel and spun the wheel. No play in wheel bearings although a slight "knock" could be heard on both sides when spun.
As isolating the front end is tricky, i put each front wheel in turn on an axle stand, started the engine and drove each front wheel up to 55mph continuously and let it "coast" - no knocking or thudding from either side.

I think my conclusions are drawing me nearer to the rear axle. I have recently replaced a wheel bearing in one side and both brake drums & shoes. The wheel cylinders have also been recently replaced.
I have also checked the front and rear output shafts on the t/box for play, and there is none.

I think rebuilding the rear axle is becoming the obvious course of action, but i'm not sure - anyone any ideas for anything else to check?

have you removed the diff ??

Diff is still in situ, but no halfshafts so it's static......

u did take the propshaft off didnt u ?

Defo - it's on the garage floor

Found the darned problem - at last!!!

Binding brake shoes

Only identified when i tried to pull the 90 off the drive and rear n/s wheel locked solid. The issue is cheapo shoes (B******t) with an incorrect radius on the drum causing them to lock on. The thudding was them locking and releasing whilst driving along...
Replaced with better quality shoes and the problem has magically dissappeared.
I did get a price for Genuine Parts shoes - £211 +VAT needless to say i didn't go for these.