ARB RD147 - Manual (Page 18)

3 Installing the Air Locker
16
3.5 Drilling and Tapping the Bulkhead Port
An airline port must be drilled and tapped through the differential
housing to mount the bulkhead fitting into.
NOTE : Higher ratio gearing uses deeper (thicker) ring gears
with teeth that extend much further. Make sure the
intended hole location is far enough away from the
ring gear teeth that the air line will not be at risk of
contact with the current or future ring gears.
Mark a position on the top of the outside shell of the differential
housing that is about 40mm [1.5”] in from the bolt face where the
inspection cover sits and located as shown in the completed
installation in Figure 8. The bulkhead position must allow the seal
housing tube (assembled at a later time) to be clear of the ring gear
position.
Figure 8.
Cover the drive pinion and axle tube areas with a rag to protect
them from metal filings.
Drill through the housing square to the outside surface using a
11.2mm [7/16”] drill.
Tap the hole from the outside using a ¼” NPT pipe tap.
Remove any sharp edges from the hole that may chip-off and fall
into the housing.
Carefully remove the rags and inspect with a service light inside the
housing to insure no metal filings are left behind.