Thread: Rear diff upgrade for RRC

Originally Posted by tebone

How much money do you want to spend? If you want reliability you have to spend a bit. I'm not sure how strong the 24 spline diffs are but I would probably go the defender 110 salisbury diff. Its a piece of mind when you are giving it a hard time. It cost me $750 + $50 to shorten the tail shaft.

Hoping to spend no more than $1000-1500...

Is the 110 rear diff the same as a P38 rear? I think I can score on of those pretty cheap/free.... providing it isn't too much cost to reverse-engineer the RRC.

Originally Posted by bee utey

For a friend's '94 LSE I have just ordered an Ashcroft air locker, fitted to a rebuilt Rover diff with pegged housing and new h/d axles and flanges to suit. Total cost landed will be around $3K. I should be able to bolt it all in over a single afternoon.

Ashcroft Transmissions

Sounds like the 'best' solution, however that sort of money is way out my budget range for this car

Originally Posted by Dougal

Is the 94 LSE 24 spline already? My 93 and 95 look like it from the outside, but I have seen photos of later style axles which are 10 spline internally.

Yes it is

And another option with the 24 splines is one of the softer LSD type diffs eg Trutrac, Ashcroft ATB. Not as hard core as lockers, but good for maybe 95% of situations?

Originally Posted by Dougal

The later 24 spline diffs have stronger spider gears and a far better axle design.

However Dave Ashcroft tested oem 24 spline axles and found them weaker than 10 spline.

Originally Posted by gavinwibrow

And another option with the 24 splines is one of the softer LSD type diffs eg Trutrac, Ashcroft ATB. Not as hard core as lockers, but good for maybe 95% of situations?

Will look into these also

Originally Posted by isuzurover

However Dave Ashcroft tested oem 24 spline axles and found them weaker than 10 spline.

That test was a single twist to failure. It's a test of material strength and not a representation of how axles break in use.

Real failures are fatigue and the 24 spline is a far better design to resist fatigue failure.

*edit*
For those interested here is Ashcrofts page of testing: http://www.ashcroft-transmissions.co.uk/halfshafts.html

Here is the rear axle graph, the 24 spline is not weaker than the 10 spline:


Here is the front axle graph, this is likely the one Ben is referring to as the 10 spline being stronger:
The 10 spline axle is softer and has twisted permanently substantially where the 24 spline didn't.

Graphs and theory

In the real world they are all rubbish if running large tyres/thrashing in the scrub

10 or 24 spline stock axles are all weak

Salisbury rear is a good idea, with some aftermarket axles

Originally Posted by Dougal

...

Here is the rear axle graph, the 24 spline is not weaker than the 10 spline:

...

Here is the front axle graph, this is likely the one Ben is referring to as the 10 spline being stronger:
...

Dave tested 10/23 and 10/32 spline (rover's silly 1.1" 32-spline) axles against 24 spline OEM.

You said yourself in a recent post that a 35/24 spline axle would be weaker than a 24/24.

Most of rover's oem axles have horrible profiles (see lower axle):

http://www.expeditionlandrover.info/...tAxleInner.jpg

Since the 10/32 (which has the smallest change in section) fails at a higher load than any of the 24 splines, AND a 10/10 spline axle (or original RRC flanged 10 spline) is likely to be stronger again for the same materials, it is a reasonable statement.

Someone in the LROCB or GCLRO (maybe Aquarangie) snapped both rear OEM 24 spline halfshafts on one trip in an ARB equipped RRC on 33's when he had previously been getting a good run out of 10-spliners...