I was using the 90 to pull a tree out at the weekend, low ratio, in reverse.

Job done, went to turn around (after engaging high ratio) and very strange sound coming from rear axle, and 90 had very strange motion as if lurching between cogs.

So, diff out and the pictures tell the story. Now I can see what has happended, but not why. I don't want to take apart as diff is being exchanged, and it is a condition that it remains intact.

When under heavy load, clearly there is a rotational force on the rear axle, which attempts to push the drive flange into the propshaft. This force appears to have forced the pinion into the crown wheel by 5mm. My questions/concerns are:
1) Is my propshaft too long - meaning it was unable to absorb the shorter distance when the axle twists, and hence forced the pinion bearing to break?
2) Are the bushes on the 2 long rods between the axle and chassis shot (they look fine).
3) Was this simply a premature bearing failure in the diff?

One clue is that the propshaft bolts had forced themselves into the end of the drive flange.

I just want to avoid shelling out money, only to see this happen again, so thoughts appreciated.

Thanks in advance.

1) I wouldn't have thought so and if it was the case you wouldn't have been able to fit it in the first place because when the vehicle is sat on the flat that is usually the point the prop will be most compressed, if you articulate the axle it pulls away a bit.

2) When reversing the rear axle is pulling the chassis back by the radius arms, so if anything it's helping increase the distances. To be so shot they started causing damage to diffs you would have heard all about it by now.

3) I think so.

When it comes to transmission parts I tend to phone Dave ashcroft if in doubt. He isn't as easy to get hold of now by phone, but email him with the photos and see what he says: Dave Ashcroft [dave@ashcroft-transmissions.co.uk]

has it made a noise on overrun recently ,pinion is supported by 2 fair size taper bearings if in good condition they would take quite an amout of thrust,flange looks out of alignment to pinion so either has failed ,take the drive flange off and put some pics of pinion and flange up

3) I also think so

Thank you to all who replied.

There was a rumble on over-run, so I expect the bearing has simply failed. Ashcroft have a replacement diff on its way today, so by tomorrow evening, should all be sorted.

It was reassuring to read your comments.

noise on over run is what happens with worn pinion bearing,