Transmission knock fault finding

Hey folks,
I've been trying to find a running order to track the transmission knocks you get in the Defender drivetrain. I have one that I am trying to diagnose, I've checked the obvious stuff and nothing presented itself. I can't reproduce the knock if I'm not driving it so it is making the faultfinding tricky.
Basically, has anyone happened upon a checklist of likely candidates? I haven't yet!!
I know you guys will provide the answers.....

Thanks as always,

Cake.

Cakebread said:

I've checked the obvious stuff and nothing presented itself.
Cake.

Click to expand...

What have you checked so far?

Sure its not the A frame ball joint or other suspension issue?

we need a bit more info ,a knock going over bumps or just in drive train when gear changing or from power to over run etc ?

@Marmaduke Just the bushes really, tricky to do a visual but had a good old swing on them to check for any play. Trailing arms, radius arms, shocks and A-frame all seem fairly good. I know it's difficult to simulate road travel on a ramp but nothing obvious popped up.

@Kwakerman I'm suspecting it is a suspension issue really, it sounds like it's rearward, so maybe A-frame but there's a niggling thought that it might be something more sinister in the drivetrain, like a diff or a driveshaft? The problem with these things is that the noise can easily travel along a chassis rail so presenting itself someplace different than the point of origin!!

@Jamesmartin The noise comes when changing up. Once the drive is released everything is quiet, when engaging the gear again you get a clunk? You do get a similar clunk on sharp power intro too. There does seem to be a fair bit of play in the props, a little more in the front but it doesn't make the same clunk and maybe not the right area either?

All in all, a frustrating time! I guess I need to eliminate the drivetrain if I can, but not sure how to do that at the roadside? If any of you guys have had similar issues then that would be good to hear about?

2004 TD5 110 doublecab.
(With North canadian trainhorns fitted, Woohoo!!)

Many thanks for posting guys,

Cheers,

Cake.

Have you done anything to it recently?

Nope. It's a fairly stock truck really, nothing much has changes since it came off the line. It's just done 80k and as far as I can tell, it's not had any major problems....

check for play in the drive train ie jack a wheel up in turn ,rock props ,diff flanges etc ,could be input gear splines, intermediate gear endfloat ,

For what it takes I'd take the large bolt of the a-frame and see what it's like when disconnected, only takes a few minutes and does show similar symptoms