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Front diff keeps breaking


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Hi 

By end of January, my Defender 90 TD5 started making some noises from the drive train. Some times some loud "kronk" noises and at some point some gear noise. Always speed depended and no matter if the clutch was engaged or not.

I vent to my local Land Rover expert, and it turned out the front diff was broken. Some bolt inside had it's head broken off, and many of the teeth of the crown wheel where damaged.

So I got a new front diff installed.
Two weeks later, the new diff has started crunching it's teeth.

So the new diff was switched again, this time it took some time to get a new one, as the first shipment was lost. But two week later I was rolling again.

Another two weeks later the new (second) diff started leaking oil at the gasket where the prop shaft is attached, and as the diff oil was all black already, the mechanic insisted to change the entire diff once again (still under warranty).
The third diff arrived fast, as the earlier shipment was found and the diff was on stock, so it got installed and once again I could drive away.

Now - two weeks since I got my third diff, I again had that loud gear noise you get when two gears don't line up. As earlier it typically starts shortly after I start my trip (before everything is warm) and typically start while turning. Again speed and not rev dependent, so everything points at the diff once again, again again...!

I stopped, reversed and vent forward again and it disappeared. And I could continue my trip. But now I guess it's just a question of time before it happens again. And the worst thing is that I completely lost my trust in my car.

The original diff had run 150.000 km, so I can accept the it failed. And one production fail would be bad luck but also acceptable, but now I'm looking at my fourth diff in 2 month, that just can't be right!

Does anyone have any ideas to if something could cause that? (No off-roading)

Regards Thomas

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I was wondering if the one that did its pinion oil seal could be down to a seized sliding joint in the front prop. Could also be a bent axle or something going on... but yeah I'd be trying a different mechanic as an experiment (or change the diff yourself) and make sure the axle is actually cleaned & flushed out.

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even 150k on the crappy 2 pin factory Rover type diff is not great. There are a LOT of variables but I can remember reading Tdci owners getting multiple diffs under warranty. It seems LR really dropped the QC with the last of the Defenders (As seen with changes in parts that had served well enough for decades, like the centre diff in the LT230)

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Petrol, paraffin or diesel and a rag on a stick to get down the axles tubes, scrape out the chunks from the bottom, keep cleaning until spotless and then drain plug out and rinse.

You'll use the worlds supply of brake cleaner if you try it, and actually, there are better things out there for stuff like this.

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On 4/11/2021 at 9:56 PM, hurbie said:

have they cleaned the axle casing ? if debris is stil around in the tube's the halfshaft's run in , it will find it's way to the diff ....

The mechanic say they had all out, cleaned and inspected.

It would be tempting to try another mechanic if it happens again, but as long as the current mechanic replaces under warranty for free, it's hard to make that decision 🙂

Edited by T.Paasch
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Yesterday I made a few tests:

1. lifted one rear wheel free from the ground, put the gear in neutral and tried to spin the wheel. It spun nicely and there wasn't much slop when changing direction before the prop shaft turned as well. So rear diff and half shafts seem fine.

2. Then I put it in reverse and tried again. The prop shaft was able to turn about 45 degrees from stop to stop, when turning the wheel back and forth.

3. Then I got under the car and turned the wheel with one foot while checking on the prop shafts. And there wasn't much play between the front and rear prop shafts on each side of the transfer box, so I suppose the transfer box is OK too (in terms om axel connections).
So the rotation of the rear prop shaft translated more or less directly to the front prop shaft.

4. Then I sat the rear wheel down and lifted a front wheel instead. I can rotate the front wheel about 8-10 cm on the perimeter before the prop shaft starts rotating. But I guess that's normal with some extra play in the front due to all the links between the front wheel and the prop shaft.

So nothing alarming there.

What stresses me out is that I don't know what to do to provoke the noise to happen. And when it comes, it goes away again when I stop or reverse, so I can't investigate it or show it to my mechanic...

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That is what I was thinking - the centre diff may be locked.  When you said you had a noise that was cured by driving backwards and forwards a bit, that sounded like alleviating transmission wind up.

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  • 3 weeks later...

I had the sound again, and this time it stayed. It was surely coming from behind this time. I jacked the rear wheel up and turned it by hand, and could clearly hear the sound coming from the rear diff.

I took out the rear half shafts, but the sound was still there (the splines looked fine). Removed the rear propshaft, and the sound was gone.
Rear diff then...

Today I took it out, and in the housing I found 5 bolt heads and 2 thread studs rattling around. All 5 where bolts holding the crown wheel that where decaptivated. The gears actually still looked good, the bolt heads apparently haven't gotten into the gears, just scratching the outside.

The sound came from one of these bolt heads being stuck between the housing and the crown wheel. Changing direction obviously previously had gotten the bolt head unstuck, but this time it stayed there.

So my first front diff was destroyed by a bolt head that broke of (probably rattled loose, unscrewed itself until it hit something inside the diff to bang its head of). And the rear diff had the same problem - a screw unscrewing itself, and one more, and one more, and one more and one more...

What suddenly makes these screws go loose after 150.000 km - is that a common thing?

Regards Thomas

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285/75 R16 BF Goodrich All Terrain. I don't off-road at all. But the car was previously owned by a plantation, so I don't know how much or how heavy work they used it for. They said it was mainly used to drive around and check the fencing was OK...

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1 hour ago, T.Paasch said:

285/75 R16 BF Goodrich All Terrain. I don't off-road at all. But the car was previously owned by a plantation, so I don't know how much or how heavy work they used it for. They said it was mainly used to drive around and check the fencing was OK...

Thanks, just trying to work out why the failure could happen, with big tyres and rock crawling you can flex the centre/ring gear and loosen the bolts as they stretch, but clear this hasn't happened here!

My money would be on someone 'rebuilding' the diffs, not using proper torque settings and no thread lock -at least that is as far as I can go with the current information. 

Were they proper land rover diffs, or just some other unknown make?

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My front diff (Td5 MY06) went at 160k in the same way. The remaining bolts could be removed by hand too.

I used it as an opportunity to install an ATB and used Allen bolts with Nordlock washers on the crown wheel. And loctite obviously!

 

J

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