Thread: Land Rover Diffs

Originally Posted by goingbush

From reading some of the posts about LR Diffs & longevity of I thought I'd take a comparison shot of the Salisbury rear & rover front diff from my 2004 110

I don't think some people appreciate how feeble the Front Rover diff is , Its almost Idetincal to the Diffs from my 1950 Series One !!!

I'm sorry, am a little confused, when you say almost identical, can you point out any differences? I'm not sure I can see any!

Probably was to do with the Salisbury company going out of business or losing the rights to the Dana 60 design or Land Rover not wanting to pay the licencing fees, something like that. I must say that when Mal Storey first saw the P38 diff he thought it was a big improvement over the tradtional Rover design, however that was before he realised that they had removed most of the meat on the shoulder of the crownwheel allowing the teeth to flex and fatigue.

Thanks for posting the photos. Interesting to see. I'm glad the true track looks more substantial. The 130 I bought a while ago came with a true track in the front diff and a detroit locker in the rear. It takes a bit more steering effort as the thing wants to go straight ahead on the bitumen under power (300tdi power! ). Off road they are awesome. Combined with the auto I can slowly idle over (nearly) anything with zero wheel spin.

Originally Posted by Lotz-A-Landies

I'm sorry, am a little confused, when you say almost identical, can you point out any differences? I'm not sure I can see any!

Only that the Defender front diff is 24 spline and the original is 10 spline, but you are correct in that you can't see that in the photo.

Also this being 3.54 the crown wheel position is slightly different to the 4.7 carrier, but for the purposes of the argument they are the same as the prewar Rover.

Ok, I'm not fluent in defender but assuming they are only part time 4WD it isn't fair to compare front and rear diffs. The front diff only takes half the load of the rear (as it is only used in 4WD) so is bound to be smaller...

Originally Posted by Matplat

Ok, I'm not fluent in defender but assuming they are only part time 4WD it isn't fair to compare front and rear diffs. The front diff only takes half the load of the rear (as it is only used in 4WD) so is bound to be smaller...

They aren't.

Originally Posted by Matplat

Ok, I'm not fluent in defender but assuming they are only part time 4WD it isn't fair to compare front and rear diffs. The front diff only takes half the load of the rear (as it is only used in 4WD) so is bound to be smaller...

Meybe good in theory but ...,

Landrovers have been Fulltime 4WD since the Series3 Stage One, (about 1980) The Landcruiser 100 series is also a 4WD that has a smaller front diff, is Full time 4WD & also blows front diffs . So the problem is not unique to LandRover.

The LR front diff was designed in 1937 or thereabouts for a 20 HP passenger car !! There are times when that front diff is taking the full power load , not quite what old grandpa Rover had in mind in 1937.

Originally Posted by vnx205

They aren't.

You learn something new every day!

My point is defunct... I completely agree with the original post

Originally Posted by goingbush

........ There are times when that front diff is taking the full power load , not quite what old grandpa Rover had in mind in 1937.

Not quite correct. While certainly all power will be transferred to the front differential if there is no adhesion on the rear wheels and the centre diff is locked, the maximum power (actually the important thing is torque, as that is what breaks things) that can be transmitted through the diff is limited by the adhesion of the front tyres. And that is directly proportional to the weight on the front tyres (everything else being equal).

For most Landrovers, the weight on the front wheels is significantly less than on the rear, and this is even more so with weight transfer in the uphill situations where low gears and full throttle are usually used.

In practice, broken bits usually are the result of transient loads, such as when a tyre slips, then grips suddenly after speeding up, when the torque can be momentarily far higher than the engine can produce as the energy stored in the flywheel is transferred to the drive train. But the front always has lower loading than the rear in the same circumstances. And, of course, the load on all transmission components in these transient conditions is directly proportional to the tyre diameter.

Although the Rover differentials are interchangeable back to before WW2, I suspect that there have been significant improvements in the metallurgy over that time, so that they are actually stronger.

Broken diffs started to appear with the S1 107, and an initial safeguard was to go to a fully floating axle and use the axle as a 'fuse'. But it was only the rear diff that broke, and this was solved by the introduction of the salisbury axle with the late S2a. And was never a significant problem with the 88, as it had a smaller maximum load.

John