As nice as it’s been to have a self-contained, automatic-locking differential in the rear of our ’04 4Runner, there were compromises that came with the territory. Some didn’t seem that bad, such as the occasional popping or banging noise as the locker locked and unlocked. You get used to it. Handling changed as the automatic locker engaged under acceleration and disengaged under deceleration. Again, you get used to it. One thing that got old too fast was the accelerated tire wear. Every time a corner was rounded with a foot on the gas (which was more often than not), the rear tires were scrubbing all the way around the turn. And it’s no secret that off-road tires aren’t cheap.
For a dedicated off-road rig, accelerated tire wear with an automatic locker is basically a non-issue. If the rig only gets driven on the weekends and the pavement miles are directly to and from the trail, tires tend to last a long time. On the other hand, tires fade faster with an automatic locker if it’s a daily driver.
Enter the ARB Air Locker. This Australian-made selectable-locking differential has long been regarded as the no-compromise solution for dual-duty driving. Unlocked, it’s an open differential: pavement-friendly and completely compatible with virtually all ABS and traction control systems. When the Air Locker is engaged, it’s completely locked up just like a spool. A locked ARB Air Locker turns both tires in unison, no matter what.
Of course, everything’s a compromise in some way or another. Unlike the automatic-locking differential we’ve been using, the ARB Air Locker isn’t self-contained. Since the Air Locker is air-actuated and selectable, an air source and a switch are both required. Fortunately, ARB offers a complete line of air compressors, wiring harnesses, switches, solenoids, and technical support to make an Air Locker installation successful.
If your off-road rig doubles as a daily driver, the ARB Air Locker is the total solution for your dual-duty vehicle. It’s transparent traction.
02. ARB offers several compressors in its lineup, including a basic model that’s meant solely for powering Air Lockers. The CKMA12 air compressor shown here is an upgraded model that’s capable of not only powering Air Lockers, but also inflating tires with an optional Pump-Up Kit (not shown). A wiring harness, switch, mounting bracket, installation manual, and fastening hardware complete the package.
03. The previously chosen 4.56 gear ratio in our Ford 9-Inch worked great when the 4Runn
04. Odds are you’ll need some new parts when a new ring-and-pinion set is installed. Rath
05. We opted for a completely new third member, including a nodular iron gearcase from Cu
06. Currie Enterprises technician Nicolas Serrato expertly installed the Air Locker and Y
07.0 The Air Locker’s copper actuating line has to be carefully routed around the ring ge
07.5 Nicolas secured the copper line to the differential case with safety wire and a care
08. To test the Air Locker’s function, shop air was applied to the connection port. The
09. American Gear Shop in La Habra, California, installed our built third member. Here, H
10. With the axleshafts set aside and the gasket surface prepped, everything was set to
12. Locating the compressor in the vehicle is up to you. The most convenient place is usually in the engine bay, but we’re trying to keep our fenderwells clear in anticipation of a future engine cage. The left rear corner of the cargo bay was our chosen spot, and we tied a custom mounting bracket into the custom mounts for our Synergy Suspension Baja Basket.
13. We used a high-temperature flexible grommet to safely route the ARB air line through the sheetmetal floor of the 4Runner. The air line needs to be routed clear of things like hot exhaust surfaces, and it needs to follow the suspension cycle on solid axle applications without snagging or stretching. It’s tempting to use high-zoot braided-steel line instead of the blue plastic line, but braided-steel line is so strong that it can pull the air line out of position inside the differential if it snags on something. Once that happens, you’ve got to get inside the differential to fix the situation. So, we used the blue plastic line.
14. Since the ARB switches didn’t fit into the OE Toyota switch openings in the dash or center console, we mounted our switches using a modified ARB mounting bracket. To make the wiring easy to get to, we routed the harness on the outside of the dash and the center console. This photo was taken before we wrapped the wiring with a split-loom sheath. If you place your compressor far away from the battery like we did, you need to extend the power wires on the ARB wiring harness. We’re planning to relocate the battery to the rear of the vehicle, but that’s another story for another day.
382 North Smith
ARB 4x4 Products
720 SW 34th Street
American Gear Shop
741 W. Whittier Boulevard