TD5 transmission backlash?

[lightning]

When you come on and off the power in our 112,000 mile TD5 90, there's a clashing noise from the transmission as if play is being taken up.
It can be avoided by smooth gear changes, but this is not always possible as it seems to have good and bad days.
Is this backlash normal at this mileage? Could it be improved by replacing the gearbox or transfer case oil?
I am hoping it's not the DMF, although the symptoms of faulty DMF are not that, according to the technical archive.

 

[jamesmartin]

jack a front and rear wheel up ,by rotating props carefully you should feel where play lies,contra rotating should show play in center diff

 

[Brown]

I've said it before on here but it might be worth repeating. I got rid of most of the 'clunk' on drive take-up with new drive flanges. A tiny bit of slack on the splines translates into quite a bit of movement in the propshaft. And probably even more in the gearbox. Other adjustments have quietened it down further, but the flanges made the biggest difference.

Hello James. Missed you!

 

[james6546]

Mine makes some good clunks the same as yours does, I think to an extent they all do.
When I get the enthusiasm up I'll take the rear diff out and investigate as the seal is leaking anyway

 

[lightning]

It's not a clunk though, it's a clashing noise like the meshing of gears.

Maybe it IS the meshing of gears, it has done over 100,000 miles. It's under warranty and l took it back but they said there was "nothing wrong".

 

[james6546]

It's not a clunk though, it's a clashing noise like the meshing of gears.

Maybe it IS the meshing of gears, it has done over 100,000 miles. It's under warranty and l took it back but they said there was "nothing wrong".

Ah, that sounds a bit different to mine, the problem is I guess that it could be any number of things.

 

[zeaphod]

100000 miles shouldn't be a problem, unless it's been very heavily worked at some stage. The question is, did it just start making this noise, which indicates a fault has developed, or has it always done it, but the noise has become louder?

 

[Tim4x4]

It's not a clunk though, it's a clashing noise like the meshing of gears.

Maybe it IS the meshing of gears, it has done over 100,000 miles. It's under warranty and l took it back but they said there was "nothing wrong".

As said it can be any number of things, if a definitive answer were available just from a description someone like James Martin would have given the cure in his post. Instead he is describing methods of investigating and then eliminating possible causes of the sounds you have.

If you are sure the noise is that of gears you have a very narrow search, diffs front rear, gearbox and transfer box.
It is just as likely not to be gears and just sound like gears as the sound is reverberating through the various parts of the transmission system, this then requires a methodical investigating approach to arrive at the culprit.
Give it a go start by completing the test as described by James and post the findings, I am sure James will give a reply to your findings and offer a next step for the investigation if that turns up nothing. he was most helpful when I had an issue with air in my brakes the cause of which was most unusual.
Can I also offer "play in the top and bottom swivel bearings" can make a similar sound as you describe.

 

[lightning]

Just to update.

This fault disappeared after a new clutch was fitted.
The noise was not the clutch itself (which was almost down to the rivets) it was transmission backlash caused by the clutch dragging when you changed gear.