Clunk then a clunk continuously under load.

[billinjah]

So pulled away from some traffic lights towing a trailer heard a bang. Then truck proceeds to clunk and a load more of a bang bang bang bang very loud inspected transfer case and chain was very very loose.

Got a replacement transfer case from Bob. Problem still remains front diff looks good inside no Swarf inside anywhere. Noise not present with front prop shaft removed. currently removing CVs to check them although they look okay with the boots slid back it’s a manual D4 D anybody got any ideas

 

[Ben Stratford]

Rear diff or prop?

 

[Shayne]

Lower wishbone bushes , its very hard to tell they are worn but i eventually worked out that mine were sliding to and fro on the bushes though i could barely do it with a crow bar when the truck was jacked up .

Remove prop and no drive to front wheels though you might hear a reminder of it occasionally when full lock parking .

 

[BobMurphy]

Bill,

My comment to you concerned the front driveshafts and where they drive the front hubs.

I have seen the splines in the hubs strip, resulting in noise, the sensation of skipping but not complete loss of drive.

Have you removed the front driveshafts completely, or just inspected the front diff ??

This is where to look for swarf:

A curious one, this .

I was thinking . . "Broken rear half-shaft", having had that on a Series III Landrover - but the noise disappears if the front driveshaft is removed.

It won't be the gearbox - it doesn't know about the drive being split between the two driven axles.

Upper or lower trailing arms or lateral support (Panhard Rod) mountings ?? That would still be there if the front wasn't driven.

Tripod bearing or CV joint on a front driveshaft. Have you removed both of them ??

Keep us posted.

With Pictures .

Bob.

 

[billinjah]

Removed both front shafts all perfect. Looked in diff no swarf or visible damage. It’s a rotational noise.

 

[billinjah]

Lower wishbone bushes , its very hard to tell they are worn but i eventually worked out that mine were sliding to and fro on the bushes though i could barely do it with a crow bar when the truck was jacked up .

Remove prop and no drive to front wheels though you might hear a reminder of it occasionally when full lock parking .

was that a rotational sound so loud other cars can hear it on the motorway?

 

[Shayne]

No not rotational .

 

[Shayne]

Kick hell out of your exhaust see it you can make it bang on anything .

 

[BobMurphy]

So, with the front propshaft removed (and the centre diff locked) the noise has gone . . . .

What is the propshaft like - are the UJs good and tight?

I have never seen a propshaft slip joint fail, but could the splines there have given up ??

Now the acid test . . . . Replace the front prop and remove the rear one. If the noise is that loud it should be easy to isolate. Does it even drive ???

It does sound like a tooth missing from the front diff - have you actually removed the front diff assembly ?? (the front diff on a '90' is not particularly strong, we are advised not to attempt recoveries in reverse or to fit 'lockers' to it. The front diff is a 'two-pinion' unit whereas the rear is a 'four-pinion').

Bob.

 

[billinjah]

That’s the next step

 

[billinjah]

Anyone got a front diff.

 

[billinjah]

It doesn’t do anything at all even towing now. I’m going to strip the front diff Later.

 

[billinjah]

Kick hell out of your exhaust see it you can make it bang on anything .

Tried that. It shakes the whole truck though. I’m sure it’s front diff.

 

[billinjah]

Well front diff looks perfect inside.

 

[billinjah]

It sounds exactly like a massive chain slipping. I guess next step is reassemble and try the rear disconnected.

 

[BobMurphy]

This is very strange, you seem to have covered all the possibilities.

We are working blind - can you post up a video (with sound) of it making the noise, that may spark some more suggestions.

(you didn't re-fit the old transfer box by mistake did you ).

Sorry . . Silly suggestion (but I'm running out of ideas) .

Recap:

You were towing and there was a loud BANG.

From then on, there is a sound like a chain skipping teeth, but the car still moves with the centre diff 'open' (true ??).

Removing the front propshaft removes the noise - car will only move with the centre diff locked (normal).

New Transfer Box has no affect on the noise.

Front diff crownwheel and pinion are OK - no missing teeth.

Front driveshafts (CVJs and tripod bearings) are OK.

Front driveshaft drive splines in front wheel hubs are OK.

Front propshaft UJs & slip-joint splines are OK (true ??)


Next Step:

Re-fit front propshaft, remove rear propshaft and drive on the front axle (with centre diff locked).


Thoughts:

We can eliminate the rear axle (crownwheel, pinion, half shafts, trailing arm towers) - true ??

We can eliminate the manual gearbox as the noise wouldn't disappear with the front propshaft - true ??

The noise is road-wheel related, it only happens when the car is moving under its own power - true ??

What happens if the car is run, in gear, with both propshafts removed (engine, gearbox & transfer box turning, but not the axles)?


I'd like to see a video.

Bob.

 

[Ben Stratford]

Woodruff key problem?

 

[Shayne]

Clutch ?

 

[billinjah]

Yes truck still moves with centre diff open.
Noise gone with front prop removed.
All splines are perfect I’ve checked every single one.
It only happens when truck is moving well it bangs as soon as you put strain on the drivetrain and move away.
We can eliminate the gear box and anything on the rear I’ve towed a heavy trailer with front prop removed to see if the noise occurs it doesn’t.
No noise with both props removed.
Front prop looks perfect slip joint included.
I’ll post a video once it’s back together.

 

[billinjah]

Turning the pinion it had a tight spot so took it out of the case looks like the bearing has bound up on the pinion and spun. Could this cause it?