200tdi - Sheared Differential Cross Shaft - Why?

Hi,

After a bit of advice if you would be so kind!

Im concious i have slipped into ramble mode here (sign of my passion in the project i took on!) If you are easily bored, skip to the bottom for a TLDR.

I am very keen to understand the cause of this failure to ensure i can mitigate it from happening again in the future and prevent any significant damage.

I think i have been very fortunate with this one, considering what could have happened!

I am a complete novice when it comes to complex mechanical jobs, previous most complex task on the landy was cutting out the fusable links and changing the rear wiper motor! However i am keen to learn, like getting hands on, and have a logical brain so thought i would give the problem a go myself and see what i could find.

I bought a haynes manual, downloaded the Landy workshop manual, bought a torque wrench, found some locktite nut locker, forgot to get gloves, and got very oiley.

I had a horrible metal on metal tinging noise coming from the rear end when the drive train was under heavy load (Gear change/pulling away), i "thought" i had narrowed it down to the rear diff causing the noise, I had a google, watched some youtube vids, ignored the haynes manual which suggested diff rebuilds were not a DIY job, and proceeded to take it off and take it to peices!

I thought i had struck gold, i found the Diff Cross shaft completely sheared just as it protrudes from one of the Center Gears.

I identified that i would need to remove the crown wheel to get the cross shaft out, so i did some homework and worked out what i needed to do to ensure i put it all back together properly. Bought myself a dial gauge, checked on the required backlash etc......

Bought a new cross shaft for 6 quid, put it all back together properly, and it worked!

However the noise was still there! I subsequently found that it was the UJ causing the noise, i took it off and the UJ was dry as a bone and rotten! Again more reading, instead of just replacing UJ's i bought a new wide angle prop to account for my 2" Lift.

TLDR Bit - The real question i want answered is as follows:
What would have caused the center shaft to shear like it has?
Thinking about its purpose logically, its job is not to be an axle of sorts for the 2 gears that revolve around it as there would be a bearing between the shaft and the gear, i assume its job is to prevent any sideways rotation in those gears?
In which case, A clean shear just as it exits one of the gears would logically suggest that it is one of two things:

• Either there was a significant force applied which rotated the gearing and the shaft did its job and prevent the rotation but sheared under pressure.
• Dodgy shaft and weakness which over time was bound to go?

Further info which may help: I have 285/75 R16 tyres and the wheels have a 30cm offset, car has standard axle parts, has a 2" lift.

I have no idea how long it had been like that, and i feel very fortunate that it did not obliterate the diff or TB or worse and want to make sure i udnerstand why it failed to prevent her from getting hurt again in the future!

P.S Sorry for wordy post. I like my detail Concious not everyone else does, if you stuck with it, thank you.

Here are pics of the damaged shaft:

Well done on repairing the diff
I have made it one of my missions in life to avoid stripping gearboxes/diffs, and replacing tires
I have only ever had to replace one diff on a Land Rover, I cannot remember what failed but I remember the oil was turning silver so I just stuck a replacement secondhand diff in

Alfdud said:

Hi,

After a bit of advice if you would be so kind!

Im concious i have slipped into ramble mode here (sign of my passion in the project i took on!) If you are easily bored, skip to the bottom for a TLDR.

I am very keen to understand the cause of this failure to ensure i can mitigate it from happening again in the future and prevent any significant damage.

I think i have been very fortunate with this one, considering what could have happened!

I am a complete novice when it comes to complex mechanical jobs, previous most complex task on the landy was cutting out the fusable links and changing the rear wiper motor! However i am keen to learn, like getting hands on, and have a logical brain so thought i would give the problem a go myself and see what i could find.

I bought a haynes manual, downloaded the Landy workshop manual, bought a torque wrench, found some locktite nut locker, forgot to get gloves, and got very oiley.

I had a horrible metal on metal tinging noise coming from the rear end when the drive train was under heavy load (Gear change/pulling away), i "thought" i had narrowed it down to the rear diff causing the noise, I had a google, watched some youtube vids, ignored the haynes manual which suggested diff rebuilds were not a DIY job, and proceeded to take it off and take it to peices!

I thought i had struck gold, i found the Diff Cross shaft completely sheared just as it protrudes from one of the Center Gears.

I identified that i would need to remove the crown wheel to get the cross shaft out, so i did some homework and worked out what i needed to do to ensure i put it all back together properly. Bought myself a dial gauge, checked on the required backlash etc......

Bought a new cross shaft for 6 quid, put it all back together properly, and it worked!

However the noise was still there! I subsequently found that it was the UJ causing the noise, i took it off and the UJ was dry as a bone and rotten! Again more reading, instead of just replacing UJ's i bought a new wide angle prop to account for my 2" Lift.

TLDR Bit - The real question i want answered is as follows:
What would have caused the center shaft to shear like it has?
Thinking about its purpose logically, its job is not to be an axle of sorts for the 2 gears that revolve around it as there would be a bearing between the shaft and the gear, i assume its job is to prevent any sideways rotation in those gears?
In which case, A clean shear just as it exits one of the gears would logically suggest that it is one of two things:

• Either there was a significant force applied which rotated the gearing and the shaft did its job and prevent the rotation but sheared under pressure.
• Dodgy shaft and weakness which over time was bound to go?

Further info which may help: I have 285/75 R16 tyres and the wheels have a 30cm offset, car has standard axle parts, has a 2" lift.

I have no idea how long it had been like that, and i feel very fortunate that it did not obliterate the diff or TB or worse and want to make sure i udnerstand why it failed to prevent her from getting hurt again in the future!

P.S Sorry for wordy post. I like my detail Concious not everyone else does, if you stuck with it, thank you.

Here are pics of the damaged shaft:
View attachment 246950 View attachment 246951

Click to expand...

I have done 2 Diffs in a similar way, put it down to playing off road and ignoring any mechanical sympathy I have.

You can get stronger diffs for the axles but they are getting expensive and getting more difficult to find.Plus you may need to upgrade the halfshafts from 10 spline .

useful link with lots of great vids on youtube.

https://www.megasquirt-v8.co.uk/diff_upgrade.php

Cheers

I have a feeling you may be able to get stronger pins, but that may be a faulty memory.
Off road driving is tough on diffs and getting airlockers helps them last, as well as making progress off road better. G-wagons I have heard come with three diff locks, which sounds very sensible to me.
I went on an off road driving course where there was one and it could certainly do everything it said on the tin!
I'd have one if I could afford it and was going to do a lot of off road stuff.
I have been stuck in mud on a flat piece of ground with all four wheels spinning in my D1. In front of my mates house. He had to secure his landy to a tree before he could winch me out. Case of not judging the ground before driving on to it.
But I digress, as I am prone to! (So I'm told!)

Big wheels and being harsh with the clutch,