ARB RD119 - Manual (Page 17)

3 Installing the Air Locker
15
3.5 Checking the Backlash
Set a depth indicator on one of the ring gear teeth (Fig.7.).
Figure 7.
While supporting the pinion gear by holding the drive shaft flange,
rotate the differential in both directions while observing the
maximum variation in depth from the indicator (i.e., the highest
value minus the lowest value). This value is referred to as the ring
and pinion backlash.
Rotate the differential carrier 90
° and measure again for accuracy.
Refer to your vehicle service manual for the specified maximum
and minimum amounts of backlash.
IMPORTANT:
It is critical to set up bearing pre-load when a differential is
installed. Improper pre-load will result in undue bearing wear,
increased stresses in the differential carrier, increased running
noise, and ultimately, ring and pinion gear damage.
Adjust the backlash and pre-load using an adjuster nut wrench to
tighten or loosen the adjuster nuts as required. (Refer to your
vehicle service manual.)