1. The 14-bolt Air Locker utilizes a variation of the new-style Air Locker that replaced the old three-piece case with a two-piece case and moved the actuator over to the other side of the unit. It features a four-pinion differential that’s locked with a big clutch ring actuated directly rather than via a long piston as before. The Air Locker operates as a normal open-diff until air pressure is applied (from 85 to 105 psi). This forces a clutch ring to lock the splined side gear to the housing and — voilà! Houston, we have achieved lockup.

2. Because Bishop’s truck had a built-in air system, we didn’t need the full ARB kit. Normally, you’d also install the ARB compressor and wiring harness. We ordered the locker unit, complete with seal housing, bulkhead fitting, air solenoid, and one of those nifty ARB switches.

3. The ARB can be installed with the axle in the vehicle, but because our 14-bolt was the lead axle in a tandem axle setup, it was easier to remove the unit. Bishop Farm’s electric forklift proved to be an ideal work platform. Pulling and working with a 14-bolt is not easy. A standard unit weighs in at 550 to 580 pounds. Bishop’s, with the various mods made for the 6x6 conversion, weighs 650 (we weighed it). Using a pair of big jackstands is an acceptable alternative if you don’t have a forklift available. Save your back and toes; use a hoist to move this beast.

4. After removing the cover and draining the oil, job one is to remove the carrier bearing adjuster lock nuts.

5. It’s a good idea to measure the backlash before complete teardown. If you duplicate this setting on reassembly, as well as bearing preload, you will reproduce the existing ring and pinion relationship and keep a nice, quiet axle. Measure in three places around the ring gear and average the results.

6. The axle shafts have to be pulled out far enough to disengage them from the carrier. Here’s a tech tip: Full float axle shafts are sometimes tough to separate from the hub. Using a pair of hammers as shown will usually pop the shaft out after just a whack or two. Not an all-ya-got John Henry whack, but a firm hit.

7. Mark the caps to the housing so they can be reinstalled on the same side as they were removed and in the same top-to-bottom orientation. A center punch does a good job of this.

8. Once the carrier bearing caps are removed, back the adjusters into the tubes one half to a full turn on each side. If you can find the special GM tool, great. Otherwise, use a long punch as shown.

9. If you’ll be reusing the ring gear, loosen all the bolts and remove it from the original carrier. It usually won’t just fall off. Leave something underneath to catch it or a couple of bolts loosely threaded. Use a punch-through on the bolt holes as shown to gently tap it off. The ring gear is hard and chips easily.

10. After washing the ring gear in solvent (or with brake cleaner), make sure the bolt-hole threads are clean and dry and install the gear onto the ARB carrier. It won’t just slip on. One option is to warm the gear in an oven (150 to 180 degrees), and it will slip on nicely. Another is shown here. Get it most of the way on, start a couple of bolts to line up the holes, and drive it evenly down with a plastic mallet. Either way, lube the carrier and inside diameter of the gear, apply high-strength (red) Loctite and torque the bolts to 120 pound-feet.

11. The seal housing is the place where most installation problems occur, so take care during this step. Assemble the o-rings into the seal housing after thoroughly lubricating everything with 90wt. Take great care to get them in straight and untwisted. Carefully install the seal housing onto the ring-gear side of the carrier with the cupped side facing up.

12. If you have a good puller, you can sometimes get the old carrier bearings off and reuse them, but it’s good practice and much simpler to install new ones. The bearing on the side away from the ring gear presses on normally. The other presses over the seal housing as shown.

13. This is the part that makes most people’s palms get sweaty. Drilling through the housing is a measure-twice/cut-once deal, but ARB gives you precise instructions on where to drill the hole. Plus, there is some leeway as to where to place it. Drill a 7/16-inch hole and tap with a 1/4 NPT tap. Make sure to protect the remaining parts in the axle from the drilling swarf and clean the housing well after drilling and tapping. Install the bulkhead fitting after sealing the threads with Teflon sealer.

14. Some housings will have clearance issues with ribbing on the ring gear side of the housing. As luck would have it, our housing was one of these. It’s noticeable when installing the ARB carrier into the housing. ARB wants a minimum of 1/16 inch of clearance between the ARB and the ribs that Bishop is shown grinding off. Note how he has protected all vulnerable parts with plastic and duct tape in the process. Vacuum out the dust, carefully remove the plastic, and vacuum again. The value of washing out the housing with solvent before this step is proven here: any loose stuff that gets away can be vacuumed, but not if it lands on oily goo and sticks.

15. Reinstall the carrier after lubricating the carrier bearings, the threads on the adjuster, and the carrier cap bolt threads. Orient the seal housing air line straight out and engage the tab of this bracket into the slot of the seal retainer and install the bolts. The washers go under the bracket. Install the caps but do not fully tighten the cap bolts.

16. Set the carrier bearing preload and backlash next, and the 14-bolt makes it easy. Make sure the adjuster opposite the ring gear is backed out well away from the bearing. Tighten the ring gear side adjuster slowly, rocking the ring gear feeling for the point when the backlash just disappears. Tighten the adjuster on the other side while rotating the ring gear until the adjuster gets hard to turn and has fully seated the bearing. Back off the ring gear side nut about two holes. Retighten the right one until it gets hard to turn again, then tighten it two holes past that point with used carrier bearings and three holes with new bearings. This sets the bearing preload.

17. Check the backlash. If it’s too wide, slightly loosen the adjuster opposite the ring gear and tighten the one near the ring gear by an equal amount. With backlash too little, do the opposite. Loosening and tightening in equal amounts retains the correct bearing preload as you set backlash. Aim for the same average number recorded on teardown. When properly set, torque the carrier bolts to spec (in our case, 135 pound-feet) and reinstall the retainers.

18. The copper air-line can be easily bent by hand. In fact, hands are the best tools for this job. Hard tools can kink the line. Shorten it as needed with a tubing cutter, then carefully bend it and insert the end through the bulkhead fitting.

19. ARB improved the bulkhead fitting design a few years back. A 5/16-inch protrusion is necessary to install the o-ring and the compression nut. This nut doesn’t need to be super tight. Pressure test the locker before buttoning up the axle. Do this by installing the compressor and air-lines before installing the axle cover.

20. Mounting the actuator switch, or switches, is partly cosmetics and convenience and partly where it will fit. On a nice truck, take the time to think about this and do a neat job.

21. All threaded air fittings should be sealed with Teflon tape or thread sealer. The air-line assembles as shown for assembly onto the axle bulkhead fitting. Overall, whatever air system is used, test the system for leaks after installation. In the case of an ARB compressor, after the locker is engaged and system pressure has been built back up, it should be at least 15 minutes before the compressor cycles again. If it cycles sooner, check for leaks by spraying all fittings and connections with soapy water and looking for bubbles. Also check locker operation with the vehicle on stands. With the trans in neutral (engine off), if you spin one wheel, the other will spin in the opposite direction and the driveshaft will not turn. When engaging the locker, both wheels will spin the same direction (it will be harder to spin them), and the driveshaft will turn.

22. Bishop teed into the main air system for the air suspension to get air for the ARB. This unit will live inside, behind the kick panel, and out of the weather. To actuate this single solenoid, all that was needed was a fused power source wired to the ARB switch. If using the ARB harness, the assembly is just about this easy as well.