4 installing the air locker, Re-shimming the backlash – ARB RD12 User Manual
Page 25

4 Installing the Air Locker
23
c While supporting the pinion gear by holding the drive shaft, 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. 
c Rotate the differential center 90
°
and measure again for accuracy.
 
 
Figure 15.
 
 
 
 
 
 
 
 
 
 
 
 
 
c Refer to your vehicle service manual for the specified maximum
and minimum amounts of backlash. If the backlash is not within the 
specifications then the differential will have to be removed and re-
shimmed. 
4.9.1
Re-Shimming the Backlash
NOTE :
This step is only necessary when adjusting for 
incorrect backlash. 
c Reapply the spreader to the differential housing. 
c Remove the bearing caps. 
c Remove the differential. 
c To increase the amount of backlash, reduce the shim thickness ‘D’ 
(Fig.5.) and increase the shim thickness ‘E’ (Fig.8.) by the same 
amount. Reverse this step to decrease the backlash. 
c Remount the differential as before. 
c Release spreader tension. 
c Check backlash again as before. 
