ARB RD138 - Manual (Page 13)

3 Installing the Air Locker
11
3.3 Drilling and Tapping the Bulkhead Port
An air line port must be drilled and tapped through the differential
housing to mount the bulkhead fitting into.
c Mark a spot on the left hand side (opposite the ring gear) toward
the top of the differential housing that is in an area well clear of the
differential, the ring gear, and any other obstructions that could
snag the seal housing tube. (Fig.6.)
Figure 6.
c Cover the drive pinion area with a rag to protect it from metal filings.
c Secure the differential housing to the work bench.
c Drill an 11.2mm [7/16”] diameter hole through the differential
housing square to the outside surface.
c Tap the hole from the outside using ¼”NPT thread tap.
c Remove any sharp edges that may chip off from around the hole
and fall into the housing.
c Very carefully, remove the rags and inspect with a service light
inside the housing to insure no metal filings are left behind.
HINT : Placing a magnet on the inside of the housing near
the hole will help to catch any debris from drilling and
tapping.