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ARB Air Lockers
 

I was a month or two over due for my routine diff fluid change.  I had gotten the rear D44 done in December.  I had a pair of leaky o-rings that I replaced and so a fluid change was done then.  I promised myself I would get the D30 done right after my Christmas vacation wheelin' time was done.  Several water crossings later (yeah, we finally got rain here in Arizona), it was mid-February and Moab is about two months away.  I reserved an hour of time on one of my regular days off and started on the D30.  I had picked up some Mobil1 gear lube and I had a fresh tube of RTV waiting to seal things up.  This was going to be a quick and easy gear lube change

 

I removed the diff guard from the front of the housing and grabbed the 3/8" socket extension to unscrew the fill plug.  The D30 plug has a magnet in it which usually comes out with a thin film of wear products stuck on it.  Needless to say I was quite surprised (and very disappointed) to see two of the above bolt pieces sticking to the drain plug when it cleared the diff cover.  While I had not seen them before, I knew exactly what they were....case bolts from my ARB locker (not ring gear bolts). 

I proceeded to remove the remaining diff cover bolts and break the RTV seal to let the oil drain into the catch container.  Once emptied, I grabbed one of those mechanics magnets from the toolbox and went fishing around in the bottom of the diff housing.  Sure enough, a total of 10 pieces were retrieved, just enough to make 5 complete bolts.  The heads had sheared off and the bolts had backed out of the ARB case.

Not much I could do at this point in time.  It was late in the afternoon and I wasn't about to try to pull the diff and find parts for it.  I tossed a shop rag in the bottom of the housing (soak up the residual oil) and put the cover diff cover back in place with three bolts holding it on.  With the Warn hubs locked out (their normal highway position), the ring and pinion gears wouldn't be rotating so I wasn't worried about lubrication for now.  The next day, I stopped by the local 4x4 shop and picked up some parts.  A new six pack of bolts and tab washers, a pair of o-rings, and new bearings and races.  The bill came to a bit under $60.  The o-rings weren't leaking but given small cost of the o-rings, it was silly not to replace them once I had the ARB pulled from the housing.  I scheduled some time with Toys by Troy for the following Monday.   I planned on doing most of the work but expected to need some help from Grady, who does the gear setups at Troy's shop. 


Fast forward to next week at the shop.  With Lady on the lift, I pulled the front tires and got down to business.  In order for the the ARB to be removed from the housing, the axle shafts must be removed (at least far enough for them to disengage the splines on the locker).  I proceeded to remove everything from the knuckles, including the Warn hubs, spindles, and finally the axle shafts.  The chromo-shafts looked good and the u-joints felt smooth.  They had been in for about 3 years but with the hubs unlocked on the highway, they only see movement when we hit the trails.  Finally, I dropped the tie-rod from the driver's side knuckle to allow the necessary access to the front of the diff housing. 


A close-up of one of the empty case bolt holes prior to the locker being removed from the housing.  That little bolt in the upper hole is the sole survivor.  I called the ARB tech support folks last week (when I discovered the problem) to see if there were any "fixes" besides the obvious bolt replacement.  Basically, the answer was no, nothing special to fix the problem.  The tech stated that the D30 housing flexes more than the larger housings and that over time, you can lose a little pre-load.  Because of the flex, sometimes the bolts shear and sometimes they stretch.  I guess mine opted to just shear the heads off.  The tech said to get new bolts for the reassembly and to check the locker for any notable problems once we had it out of the housing.  He offered to let me send it to them for inspection but I decided it would be cheaper and faster to pass on that....but thanks ARB for the offer.  As it turned out, there was not other damage we could find during our inspection. 


Before the locker could be removed from the housing, the copper air line had to be disconnected from the bulkhead fitting in the housing.  An easy way to accomplish this is to first remove the blue 6mm ARB air line. 


Next, remove the brass coupler from the bulkhead fitting.  A 9/16" wrench and a 3/8" wrench does the trick for this step. 


I then unscrewed the bulkhead fitting from the housing.  This gives one the most space for navigating the copper air line (with the compression ring) out of that hole.  Be careful when moving the air line.  The old lines, like mine, are quite stiff and are more liable to kink than they are to bend if you are not careful.  Mine had been somewhat flattened when it was first installed and as I tried to move the line, it cracked right where it comes through the bearing cap.  I went ahead and bent it a little more to finish the job.  Not a major problem, I suspected this might occur and so I just happened to have a new seal housing (which the copper air line is attached to) sitting in the back of the TJ.  Troy thought the seal housing may have been damaged from the case bolts being sheared so at the last minute, I picked one up just to be safe.

Once the copper air line is free of the housing, remove the bearing caps (two bolts per cap).  Note their position.  It is easy to tell left and right (in this case because of the air line) but you also need to pay attention to which end is top and bottom prior to removing them.  It is important to install them in the same position as they were removed.  If you don't, you stand a chance of having the axle shafts and differential be out of alignment with each other once you assemble everything.  That leads to short life spans of the rotating components.


With the bearing caps removed (and my copper line really removed), it is time to extract the differential from the housing.  One way to do it is to put a box end wrench over a ring gear bolt.  Once in place, slow rotate the locker up until the wrench comes in contact with the housing.  Then, take a pry bar and slip it between a pair of ring gear teeth at the bottom of the housing.  As you carefully push on the pry bar, it will cause the locker to rotate up and out of the housing.  BE CAREFUL!  Don't drop it....and note that there are shims on the end of the bearing on the driver's side.  If you have a friend nearby, ask them to help....this is one of those extra pair of hands procedures (at least until you get good at doing it solo!). 


 

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