ARB Air Locker RD111, Installation Manual

Page: 12 / 42

3 Installing the Air Locker
10
3.2
Calculation & Selection of Backlash Shims
Ideally, the measurement you recorded as ‘
C
’ from the
Air Locker
diff
erential will closely match ‘
A
’ on the existing differential (within
0.1mm [0.004”] ) and then the factory shim can be reused, 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 Figure 3.
Use the following calculation:
A + B – C = D (
Replacement Shim Pack
)
HINT : If your calculations are correct then the following
calculation will also be true:
A + B – C – D =
ZERO

Create a shim pack to match the thickness calculated as
‘D’
.
To achieve the desired shim thickness you can:
•
Machine down the factory shim thickness.
•
Add shims between the factory shim and the bearing cup.
HINT : A selection of shims of this size have been supplied
with your Air Locker kit.
•
Purchase new factory shims at the desired thickness.
•
Use a universal shim kit available from most drive train
specialists.
•
Add small amounts of shim between the bearing cone and the
bearing seat.
NOTE : NEVER machine the Air Locker.