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ARB O-Ring Replacement

removing air line from bulkhead

The copper air line must be removed from the bulk head fitting.  Use a small wrench to remove the compression nut. 

bearing cap removal

With the air line detached at the bulkhead fitting, the bearing caps can be removed.  The Dana axles have orientation marks on the bearings caps and the housing so that you can properly identify and position the right and left bearing cap.  The housing is bored with the caps in place and it is important to ensure they remain in the correct position during reassembly.  I make it a habit of using a small center punch to mark the top of the bearing caps, using 1 dimple on one side and 2 on the other (if I have a problem reading/finding the factory marks).  This allows me to easily position the cap during reassembly.  Since the bearing cap with the drill air line hole can only be installed one way, you really only need to mark/identify the top of the other bearing cap.

The locker fits very tightly (referred to as preload) in the housing.  While some folks use a case spreader to slightly force open the housing, most techs I know don't use that method.  I spoke with Grady, one of the guys that works at the TBT shop, and inquired as to his favorite method of extracting the locker from the axle housing.  Pry bars is one of his normal methods.  We tried a large one (seen in the above photo) but didn't have much luck budging the locker.  It was in there very snuggly.  I've seen a pair of them used to pry the locker out of the housing.  We finally resorted to using the slide hammer in the above pic.  The hook on the end was placed against the ring gear and it was gently "tapped" out of the housing.  Be careful of the shims when removing the differential from the housing.  You want to be sure they go back in the same way they came out.  This sets the preload and the setup between the ring and pinion gear.  As long as this is not changed, there is no need to check the gear setup when you are done.

As I was straightening the air tube on the seal housing a bit, I felt the tube crack.  Before we even removed the bearing cap, you could see where the tubing had been kinked just a small amount.  It had been suggested to me by a good friend that I might want to get a spare seal housing to have, just in case, when doing the o-ring replacement.  As it turned out, that was good advice indeed.


With the locker sitting on the bench, the seal housing was slipped off.  Beneath it are the two o-rings that were to be replaced.  I couldn't see anything wrong with the o-rings and likewise the seal housing surface looked OK too.  Given that I was not leaking air from the housing, I guess I couldn't expect them to be in that bad of a condition.

The old o-rings were removed and a careful inspection of the grooves were made, just to make sure there were no rough edges, etc. to cause an o-ring problem.  The groves were thoroughly coated with fresh gear lube and the o-rings were likewise lubed up.  The rings where then carefully put into the grooves, making sure not to roll the o-ring into position.  If you try to roll the ring between your thumb and finger, you can feel the resistance build up as the ring twists.  It is pretty easy to feel the o-ring slip into the groove correctly when you mount them.


With the o-rings installed, I turned my attention to the housing.  I used some brake cleaners to clean the residue out of the housing....that stuff that kind of coats the bottom of the housing.  I cleaned up the sealing surface using a gasket scraper, getting rid of the old RTV that was used to seal the cover in place.  Take a couple of minutes and also check the pinion gear teeth, making sure there are no chipped or broken teeth.  Likewise, check the teeth on the ring gear. 


With the housing cleaned up, the ARB was placed back into the housing.  A dead blow hammer was used to gently tap the carrier into position.  You want to be sure to line up both ends as you get it started.  It is easy to get it cocked off to one side a bit and results in things becoming much more difficult.  Once it gets a little further into into the housing, you can whack it pretty hard with the dead blow hammer to seat it the rest of the way.  You will know when it "pops" home in place.  Be careful to NOT hit the copper tube!


At this point, you are almost done!  Put the bearing caps into position (remember to get the top/bottom aligned correctly).  On the D44, the bolts are torqued to 80 ft. lbs.  Snug them down in a criss-cross pattern until they are fairly tight and then finish them with the torque wrench.  The copper air line is then reconnected to the bulk head fitting.  The copper air line needs to be located so that it does NOT rub on the cover nor make contact with the rotating locker.    Do a double check on everything and then reattach the blue air line to the outside of the bulkhead fitting.

Right now is a GREAT time to check for air leaks in your system.  Better to find a leaking copper air line compression fitting now then to have to redrain the housing and go looking for it later.  I knew my ARB compressor was in good condition for I had tested it just a week ago and it held pressure for several hours without the compressor kicking on.  Knowing that, all I had to do was to energize the compressor and then engage the locker and let them set.  If there are any leaks in the o-rings, seal housing, or any of the fittings at the bulkhead connector, the compressor will bleed down in short time and turn on again to recharge the leaky system.  I let mine sit for 45 minutes with the rear locker engaged and the compressor did not cycle.  The ARB owners manual states that a 20 minute leak down test is adequate so I felt confident my system was doing very well. 

At this point, it is time to put things back together.  I coated the sealing surface on the diff cover with RTV and it back on the housing, along with the diff guard.  The truss bracket was then reattached.  I took a few minutes and cleaned up the axle shafts just a bit.  As I had mentioned, a small amount of RTV had been used on the external surface of the seal to help ensure no gear lube leaks at the end of the axle tubes (I hate gear oil on the brake pads and the e-brake shoes).  With the shafts looking to be in good condition, a bit more RTV was spread around the outer edge of the seal and the axle shafts were slid back into the tubes and the retaining plates tightened down.  The brakes were reattached and the tires mounted and lug nuts torqued.  DONE! ..... well, not quite.....don't forget to put some gear lube in the diff housing. 

Because my D44 is rotated a fair amount to provide the proper pinion angle for the CV drive shaft, I can't get more than a quart into the housing without a little help.  That little help is to either park the vehicle on a steep down hill slope (front bumper going down hill) or to back the rear tires up onto a set of wheel ramps.  Either way, it raises the rear of the vehicle and allows me to get at least another half quart of gear lube in the housing. 

You are done.  Time to go out and enjoy your Jeep on a nice trail! 

Remember to always TREADLightly!




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