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ARB O-Ring Replacement

One day on the trail I hit my front locker and my compressor just ran and ran. I new I had an air leak, but I wasn't sure where it was. I did the normal thing and popped my hood and hear air coming up from the radiator, but that didn't make sense because there isn't an air line there. After some more digging we realized it was coming from my axle housing vent tube. That can mean one of two possible problems. The air line has come loose in the housing or an O-ring has failed. I was able to get 4 good years out of the front/rear. The rear is still working so lets see how much longer I can go before it fails.

ARB lockers work great, but even they have a weakness. Its a small O-ring that costs no more than a couple of bucks. The only problem with replacing the O-ring is you have to literally take your ARB locker out of the axle housing which means you guess it. Everything must come out/off. Wheels, calipers, rotors and axle shafts. Its not really a difficult task, but just time consuming.

Tools: Time:
5/8ths socket and driver
Pry bar
2x4 chunk of wood
13mm ratchet
2+ hours

This project wasn't really a difficult project however most simply do not want to mess with the inner workings of the Differential because of the problems it could cause. I was told one thing and one thing only. "Put it back together exactly the way it came out. Take tons of photos and do not screw it up." This procedure assumes you have the knowledge of how to at least remove the diff cover. If not you can follow this one here. Servicing your Diffs Written by kizer, if you have any questions or comments about this install visit


Remove the Castle nut and pin from the drivers side knuckle so you can easily raise the Tie-Rod

I like to hit the flat spot on the knuckle a few times and the Tie-Rod end will just fall out.

Zip tie up the Tie-Rod to the drag link and its out of the way so you can catch the ARB as it comes out.

I always take a photo or two of everything I do for reference. This is no exception because I wanted to make sure everything went back together the way it came out.

Notice the lettering on the Bearing Caps. The lettering is right side up if your tilt your head to the right "Drivers Side". You can't see it very well in the photo, but the right Bearing Cap "Drivers Side" There is a N stamped into the bearing cap in this position. Z. As well its stamped into the mating surface of the housing. It should help you remember, but take photos, make notes anything. Some will place a spot of paint or tap the tops of the caps with a punch. Make sure you put the left on the left and the right on the right.

Remove your Brake Calipers and Rotors

Remove the 3 bolts on the back side of each knuckle. It should be a 12-point bolt. 13mm

Pull out the Axle Shaft along with the Unit Bearing as one piece.

I like to place things like this on a towel and wrap the end to keep any thing from contaminating the splines.

Shove a clean rag inside the opening. Make sure you DO NOT push any dirt or debris inside the housing.

Remove the air line from the housing. Mine is just a simple compression fitting which released as soon as I removed the connection.

I believe the Bearing Cap bolts are 5/8ths.

Place the Bearing Caps down in a manner so you know exactly how they go back on.

Pulling the carrier out was pretty easy. I've seen others use a fancy puller or a slide hammer. I just placed a 2x4 on the mating surface of the axle tube and a pry bar and it slide right out. There was a little bit of effort required, but not much.

3 small shims out board of the Seal Assembly "Passenger Side. Master shim and a few other shims outboard of the bearing on the "Drivers Side", which in this photo are hanging from the air line.

Its not noticeable, but the Master Shim is the thick shim and its beveled edge is facing "Drivers Side" with the smaller shims up against the bearing.

Pulled the Seal Assembly off the ARB. Notice how the air line comes out of the Assembly and arcs to the left. On the right there are some more shims. The beveled edge faces the ARB

Just under the Seal Assembly there is a hole which is where the air enters the ARB to lock.

Here's the hole in the Seal Assembly where air exists and enters into the ARB.

Also look at the O-ring. It round and its contact point is in the center of the O-ring.

Looking at the Seal Assembly you can see the damaged O-ring. As well the Seal Assembly looks like it has been worn on the outer edge.

I was unable to get a new O-ring inside of it and had to order another one. The cost was approx. $35.00 from ARB.

Here's a picture of the new O-ring. Notice it has two contact points per O-ring. Its ARB newest design.

First thing I noticed when I pulled the new Seal Assembly out of the box it looked a little different. The new one has to holes drilled in it.

On the Seal Assembly there is a beveled shim and a really thin shim.

This is how it looks with the shims installed. Notice here on the old Seal Assembly there is literally no gap where the screw driver tip is.

Here on the new Seal Assembly there is a gap and there are two holes unlike the old Assembly.

I contacted ARB and they said it was part of their new design The holes allow gear lube to move through out the ARB and the gap acts as a channel.

After a few minutes of head scratching it made sense because the seal sits on the ARB from the inside and the outer edge is sandwiched between the Bearing and the Axle housing.

I placed the old Seal Assembly up against the new one. Noting like doing a few bends to make it match as close as possible. Just make sure your careful and support where it enters the Assembly. You DOT NOT want to break the solder connection because it will not hold air pressure.

Welcome to my poor mans measuring device. I cranked my vice as tight as I could without putting any pressure on the Seal Assemblies and made sure each Assembly could slide though so I could gauge if they where the same thickness. I didn't notice anything.

After you have your O-rings installed lube up the O-rings with a generous amount of Gear Lube and the shaft of the ARB. Like screwing on a cap slowly twist on the Seal Assembly with some downward pressure. Do NOT forget the shims otherwise you'll have to take it off. =)

I used a small bottle like this full of gear lube to wet down the shims and axle housing as I held them against the carrier, bearing and seal assembly.

I didn't take a lot of photos during the reinstall, but I can tell you this. You want to make sure the carrier and shims go in straight at the same time otherwise your going to be fighting it. I used a rubber mallet and tapped the carrier side to side as it went in.

Push up on the air line so it sticks out far enough so you can get your compression fitting on it.

Not shown in the picture before, but there is a small O-ring on the end of the air line that the compression fitting bites against, which makes the seal and prevents it from leaking.

I had to purchase a new master shim because I didn't think ahead and lube up the shims and housing before trying to slide everything. I was lucky that ARB had them in stock and sent them to me for free. You can not just purchase the master shim. It comes part of a package of approx. 10 shims of various sizes, but it is the thickest and the only one that is beveled.
I didn't really photograph the reverse order of putting things back together again. However here's a quick order of things.
1. Slide in the axles with the Unit Bearings torque the 3 bolts on each down to 75-lbs
2. Install the Rotors and Calipers and torque down the calipers to 11-lbs
3. Reattach the Tie-rod end and Tie-rod and torque castle nut to 35-lbs
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