ARB RD117 - Manual (Page 14)

3 Installing the Air Locker
12
3.3 Approximate Backlash Shimming
In order to reproduce a similar pre-load and ring and pinion backlash
in your Air Locker to that of your original differential, measurements
need to be taken so that a shim thickness can be calculated.
Secure the original differential to a work bench.
Remove the bolts that hold the ring gear in place.
Using a plastic or copper hammer, tap in a circle around the ring
gear to separate it from the differential carrier.
Figure 6.
Assemble the original bearing cup onto the cone of the right-hand
side of the original differential carrier.
Using a caliper or similarly accurate measurement method
(i.e., able to take accurate measurements within 0.04mm [0.0015”]),
measure the distance from the shoulder of the outer face of the
bearing cup to the ring gear mounting face (shown as ‘A’ in Figure
6.) and record this measurement as ‘A’.
NOTE : Be sure to measure using the bearing cup that
originally came off of the right-hand side.