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ARB Air Lockers


With the locker sitting on the work bench, we removed the remaining cylinder cap bolt.   The cylinder cap can then be lifted off of the case (note it is under just a little bit of spring pressure).  The orange object you see in the cylinder cap is the air diaphragm, or "U-ring" as ARB calls it.  When you flip your locker switch, the air solenoid on the compressor opens and applies 90 PSI to this part of the locker.  It in turn pushes against the piston (that black ring sitting on top of the locker case in the above pic) that causes a large locking gear to lock the differential.  When you turn off the locker switch, the air is vented from the diaphragm and small springs push the locking gear back to its disengaged position.


We cleaned the gear lube from the bolt holes using some cleaner and blew it dry using compressed air.  Be careful with the compressed air as the retaining pins that hold the cross shafts in place can easily be blown out of the housing (don't ask me we discovered that one). 

With the cylinder cap placed back into position, the new case bolts were given a dab of thread locker and threaded into place.  ARB states the bolts get 13 foot pounds of torque.  I had my inch pound wrench along and we dialed that in and made quick work of the bolts.  New tab washers that I picked up at the 4x4 shop were pushed down over the tops of the bolts to secure them in position.  The easiest way to do this is to center the tab washer over the top of the bolt head and pop them down into position with a gentle tap from a hammer and a socket (use the same socket you put the bolts in with and a short extension attached to it).


From here, Grady pulled the old bearings and pushed the new ones into position.  In the above pic, you can see him using one of those handy bearing pullers that is powered by an impact wrench.  Takes about 3 seconds to pull the bearing from the locker.   Yet another reason I don't do this work in my garage.....I don't have the tools to do it, let alone the experience to get it done correctly.



Before the locker was put back into the housing, I cleaned the "junk" from the axle tube seal area.  If you run your finger around the center of the shaft seal, you'll most likely find grit, sand, etc.  It collects over time and is what ruins your seals when it gets into them and your axle shaft spins.  I wiped them cleaning using a paper towel and some gear lube.  After they were clean, I grabbed the shop air hose and blew the rest of the loose dirt/sand out of the axle tubes (blow the air through the seals out to the end of the axle tubes).  Quite a bit of debris came out. 

Note:  When you insert your axle shafts into the diff, try the best you can to NOT slide the splined end along the tube on its way to the seal.  Doing so does nothing but harm, as it gets sand and dirt in the splines and also onto the sealing surface that it going to keep the diff fluid on this side of the seal.  You can insert the driver's side shaft without letting it hit the tube, but doing the passenger side is pretty tough.  Do the best you can and minimize what the shafts get pushed through.

From here, we reinstalled the locker into the housing.  Make sure all the shims go back in correctly and get it all aligned before driving it home.  Grady checked the pre-load and was satisfied with it. 

This locker is the older RD-30 model.  Not too long ago, ARB released the RD-100 model which was an upgraded design for the D30 model.  Major differences of the RD-100 is the seal housing location being on the passenger side of the diff and a new two piece case design.  This new case design eliminates the cylinder cap bolts and the two sections of the locker case are now held together with the ring gear bolts.  Once this new model gets some years of service behind them, we'll all have a better idea of how well they will hold up.  ARB is known for making good products and I see no reason this new model won't be a good one. 

From here, I just reversed the tear down process and restored everything back to the way it was.  Don't forget to use anti-seize on your hub bolts....in fact, put a thin film around the inside of the knuckle where the unit bearing slips into position.  Doing so will help you the next time you take things apart.  



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