Fitting Ashcroft Air Lockers to a Defender 300 Tdi

Traction is almost everything off-road, so get a grip and
fit a locking axle differential. Neil Watterson explains how

You’ll need when Fitting Air Lockers

  • Differential centre, Air compressor, Shims

Tools used

  • Sockets, Torque wrench, DTI dial gauge
  • Drive flange holding tool, Engineers Blue
  • Drill and 11.5mm bit, 1/4BSP tap
  • Diff bearing adjuster tool, Hydraulic press

Safety – Read Before Fitting Air Lockers

  • Keep everything spotlessly clean, Wear goggles when drilling and safety boots when handling the diff, take care lifting the diff.

My LR 90 is a workhorse and I expect it to get me everywhere.  Although I carry a fair amount of recovery gear with me, I prefer not to use it, and to stay in the relatively warm cabin, rather than messing around in the cold and wet – so anything I can do to keep the vehicle moving is a bonus.

We fitted an onboard air compressor a couple of months ago and that gave me the basis to fit an air locking differential.

I chose to fit one of the PM104 Ashcroft Lockers. This is a heavy-duty locker for the standard Land Rover differential fitted to Defender, Range Rover Classic and Discovery 1 and 2. It features a locking collar with a full 6mm of engagement – some others only have 2.5mm of engagement – so won’t suffer from slipping out of lock when under load.
I had the differential built at the Ashcroft Transmissions workshop. The locking centre is supplied fully built. We started off with a fully stripped and cleaned diff; if
you are dismantling yours, ensure you mark the bearing caps before you start work and keep all of the shims. You may not have to remove the pinion, but we’ve showed how to build up the diff for completeness.

We already had a Quaife ATB fitted in the rear axle.
I’ve moved this to the front axle and the Ashcroft Locker is now in the rear.

The above content originally appeared in LRO magazine and is reproduced here with the kind permission of LRO and their sponsors Britpart. Any advice or opinions are those of LRO magazine and its writers.