In 2002 LandRover decided to replace the 110 rear Salisbury axle with a pressed steel axle housing (similar to the 90) with the P38 / Wolfe type short housing 4 pin diff. The Salisbury axle had its pros and cons but the diff was very strong and the P38 / Wolfe diff was seen as a step backwards.
The P38 diff ring and pinions can fail but also often suffer from noise issues which we think stem from the pinion bearings having higher load as they are closer together than the rover diff and also tend to shear the crown wheel bolts as well as suffer from pinion bearing failures, again we suspect from being too close together.
The axle housings are generally OK and the Salisbury and P38 axle both use 24 spline shafts which are OK but HD shafts are available for both axles if required. Because of this we have been looking at different solutions for a stronger rear diff for the post 2002 110 but keeping the existing axle and half shafts to keep cost down and simplify installation.
In looking for a solution we saw no reason to change the diff centre and if we could design a diff around the normal rover centres we would be able to utilise the existing range of 4 pin, ATB Limited slip diffs and Air Lockers.
The design we have decided upon is a new diff housing which has a hypoid ring and pinion with a 1.5” of hypoid offset and with a longer pinion so the bearings can be moved further apart (like the rover type diff).
For those not familiar with this, the Landrover design is a bevel gear ring and pinion, ie looking from the side, the pinion is on the centreline of the ring gear, a hypoid design has a lower (or higher) pinion, in this case 1.5” lower than the ring gear centreline. This puts more teeth in contact and greatly improves the strength of the ring and pinion. The tooth count is the same as the Landrover diff at 46/13, ie 3.54 ratio.
In comparison to the stock pinion :
We have addressed some of the other known issues also, i.e.
Changed the crown wheel bolts from 3/8 UNF to 7/16 UNF, (we machine out the 10 crown wheel holes on the rover centre to fit)
Comparison of stock bolt and new :
Note as the pinion is longer, a shorter rear prop must be used, it needs to be 31mm shorter but we have found that for the 110 FTC3905 which is a Salisbury 110 rear prop shaft will fit and is available for £ 110 + V,
We have tested these very thoroughly and have a small batch available for sale now.
We have analysed the common failures of these diffs and adjusted our design to eradicate these weaknesses, ideal for heavy overlanders, those that tow regularly and for high torque engines.