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With the O-rings in place, Donnie took the seal housing and slipped it into place. I asked him if this was the place where unfortunate installers screwed up the O-rings and he confirmed it was. He slid the seal housing off of the bearing journal so I could better see what was going on. Plenty of lube and a twisting motion while pushing on the seal housing ensure that the O-rings stay in the grooves and remain undamaged. Donnie has the technique down just right because those O-rings looked just as good when he pulled the seal housing to show me how it was done. (and I am glad!) You can see the metal tubing that supplies the air to the seal housing in the above picture.
With the locker set aside for now, Donnie turned his attention to the differential housing. Time to get the air drill and make a hole for the air line fittings. This is where the metal tube from the seal housing interfaces with the 5mm nylon tubing that comes from the compressor. Donnie drills the hole in two stages, using a smaller diameter bit for the first pass and then the final size bit to finish it up.
Next comes the tap. A 1/4" NPT tapered pipe thread tap is used here. Donnie made sure the tap was square to the housing when it got it started. He said he prefers to leave 3 threads showing at the big end of the tap. Since this is a tapered hole, it allows the bulkhead fitting to bite tightly into the hosing when it is installed. Donnie said he never gets a leak this way and does not require any thread sealant of any kind.
With the residue from the hole properly clean out of the housing, Donnie fits the ARB into the housing. Using the shim pack that came with the air locker, he set the carrier bearing pre-load for the ARB. Yeah, that is one of those big dead blow (is that what they call it) hammers.
With the locker properly seated, Donnie takes some measurements for the hole that must be drilled in the bearing cap. He had a pretty good variety of stories to tell about the various bearing caps (and seal housings) that he had encountered since working at 4 Wheeler's. This is a critical step where the old saying of "Measure twice, drill once" is advice well taken.
With the hole for the bearing cap properly marked, Donnie chucks it up in a vice and drills the 1/4" hole. Since the bearing caps are mated with the axle housing at the time of manufacture (they are bored by the manufacturer as a single unit), you really do want to make sure that you only have to do this step one time.
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