Preload + end float = shim pack, 3 installing the air locker, Calculation & selection of preload shims – ARB RD111 User Manual
Page 17: Drilling & tapping the bulkhead port

3 Installing the Air Locker
15
3.6
Calculation & Selection of Preload Shims
c Consult your vehicle manufacturer’s service manual to determine
the carrier bearing preload amount specified for your vehicle.
NOTE : If your service manual specifies preload in terms of a
torque value measured off the drive pinion flange, 
then assume a preload amount of 0.25mm [0.01”] for 
the following calculations. Once you have assembled 
the housing to check the final backlash (Refer to 
Section 3.12 Checking the Backlash) you should verify 
that your preload is correct using a torque wrench and 
your service manual’s table of values. 
c Add the specified preload amount to the end float measurement
determined with the feeler gauge to determine a shim amount for 
‘E’ (Refer to Figure 5.).
PRELOAD + END FLOAT = SHIM PACK
c Create a shim pack ‘E’ to closely match the measured amount.
NOTE : Do not add shims between the bearing cone and the
bearing seat and NEVER machine the Air Locker.
3.7
Drilling & Tapping the Bulkhead Port
A port must be drilled and tapped through the shallow half of the 
clamshell to allow the seal housing tube through the housing to 
connect with the air line from the air compressor. 
c Remove the Air Locker from the housing. 
c Press the shims, seal housing and bearing cup out of the bearing 
bore of the shallow half of the clamshell.
c Mark a spot on the shallow half of the clamshell in the same
position shown in the photograph in Figure 7. and Figure 8.
