ARB RD131 - Manual (Page 11)

3 Bench Measurement
9
Measure the thickness of the factory shim removed from the end of
the differential carrier (shown as ‘B’ in Fig.3.) and record this
measurement as ‘B’.
Figure 4.
Measure the distance from the Air Locker bearing shoulder to the
ring gear mounting face (shown as ‘C’ in Fig.4.) and record this
measurement as ‘C’.
3.2
Calculation & Selection of Shims
Ideally, the measurement you recorded as ‘C’ from the Air Locker
differential will closely match ‘A’ on the existing differential (within
0.1mm [0.004”] ) and then the factory shim can be reused on this end,
however, quite often these measurements will vary slightly between
one factory differential and the next.
If this is the case you must create a new shim pack thickness by using
the measurements you recorded earlier to find a desired measurement
for ‘D’ in Fig. 4.
Use the following calculation:
A + B – C = D (Replacement Shim Pack)