Arb Air Locker Install Kit: Step-by-Step Guide for Trail Rigs

An arb air locker install kit gives you everything needed to convert an ARB Air Locker equipped differential from open or limited-slip behavior to a fully locked axle, using compressed air to engage the locking mechanism on demand. In this guide you will learn what the kit typically contains, how to verify compatibility, the tools you will need, and a clear sequence for installation, air line routing, and testing. Work carefully and follow the manufacturer’s torque specifications, because a locker is only as reliable as the install behind it.

What an ARB Air Locker Install Kit Includes

Most ARB air locker install kits are built around the specific axle and carrier the locker was designed for, so the contents vary by application. Manufacturers generally specify the locker unit, the air actuator assembly, the solenoid or valve hardware, and the fittings and tubing needed to connect to your vehicle’s air supply. Always check the kit’s packing list against the part numbers for your axle before you begin.

• Locker assembly with ring gear hardware and spider components
• Air actuator, piston, and internal seals
• Air solenoid or control valve and mounting bracket
• Nylon air tubing, push-to-connect fittings, and a bulkhead fitting
• Wiring harness, relay, and inline fuse
• Installation instructions with torque values and gear setup specifications

Confirm Compatibility Before You Start

Before you pull a single bolt, confirm the kit matches your axle housing, ring gear diameter, pinion depth, and spline count. Mismatched carriers are one of the most common reasons an install fails, and the problem often does not show up until the locker is under load. Check your axle code, usually stamped on the housing or found on a door sticker, and compare it against the manufacturer’s application list.

You should also confirm that your gear ratio and pinion bearing preload procedure match your existing setup. If you are changing ring and pinion gears at the same time, plan for a full gear set rather than trying to reuse worn parts.

Check Your Air Supply Capacity

An air locker needs a reliable source of compressed air. Many owners run the lock from an onboard compressor, a dedicated air tank, or an existing air system if the vehicle already has one. Confirm that your supply can hold pressure at the actuator’s rated operating range and that the tank is sized for repeated engagements on the trail. Expect to add a moisture filter or air dryer in cold or wet climates, because condensation in the lines can freeze or cause valves to stick.

Tools and Supplies You Will Need

A proper install relies on the right tools and clean working conditions. Gather everything before you start so you are not stopping mid-job to hunt for a socket.

Item	Purpose
Torque wrench (calibrated)	Set ring gear bolts and carrier caps to specification
Dial indicator and magnetic base	Verify ring gear backlash and pinion depth
Bearing puller and press	Remove and install carrier bearings
Thread locker (medium strength)	Secure bolts where the manufacturer calls for it
Gear marking compound (Dykem or similar)	Check tooth contact pattern
Tubing cutter and air line fittings	Route and terminate pneumatic lines cleanly
Multimeter	Test solenoid power and ground
Shop rags and degreaser	Keep the carrier and housing clean

Step-by-Step Installation

The exact order depends on your axle, so treat the manufacturer’s instructions as the final authority. The general sequence below applies to most differential swaps.

Step 1: Drain and Remove the Axle Cover

Drain the differential fluid into a suitable container and remove the cover. Clean the housing thoroughly, paying attention to the mating surfaces and the area around the pinion seal. Any debris left behind can work its way into the new gears.

Step 2: Remove the Carrier and Disassemble

Unbolt the carrier caps, mark their orientation, and remove the carrier from the housing. Set the caps aside in order. Pull the existing differential components and inspect the carrier bearings and bearing bores for wear or galling.

Step 3: Assemble the Air Locker Into the Carrier

Install the locker into the carrier following the kit instructions. Seat the actuator and piston components and confirm they move freely before final assembly. Lubricate the seals with the recommended assembly lube so they do not pinch during installation.

Step 4: Set Preload and Backlash

Install the carrier bearings and ring gear, then set bearing preload and ring gear backlash to the specifications in the instructions. Backlash is typically checked with a dial indicator at several points around the ring gear, and the pinion depth is verified with a gear marking compound. Hold a consistent contact pattern across the teeth before you close up the housing.

Step 5: Route and Connect the Air Lines

Mount the solenoid or control valve in a protected location, away from the exhaust and tire path. Run nylon tubing along the frame or axle, securing it every 12 to 18 inches with zip ties or clamps. Keep the line clear of sharp edges, moving parts, and heat sources. Connect the line to the bulkhead fitting at the housing and to the actuator port, then pressurize the system and check every joint for leaks using soapy water.

Step 6: Wire the Solenoid

Connect the solenoid to a switched power source through the supplied relay and fuse. Ground the solenoid to clean bare metal. Test the circuit with a multimeter before you energize the valve, and confirm the switch engages and releases the lock as expected.

Step 7: Reassemble and Fill

Reinstall the carrier, torque the caps to specification in a crisscross pattern, and install the cover with new gasket or sealant as needed. Fill the differential with the fluid type and quantity specified for your axle. Check the level after the vehicle has been driven briefly and settled.

Testing and Break-In

Before you head onto the trail, test the locker in a controlled environment. Engage and disengage it several times while the vehicle is stationary and raised on jack stands, watching the wheels for a clean lock. Then drive slowly in a straight line and make tight turns to confirm the locked axle does not bind excessively on pavement. Some binding in tight turns is normal with a locked axle, but grinding, clunking, or a sudden lurch indicates a problem. Recheck torque on carrier bolts and the air fittings after the first few hundred miles.

Common Mistakes

• Skipping the dial indicator check and relying on feel for backlash.
• Running air lines too close to the exhaust or tire path, causing heat or abrasion damage.
• Using undersized tubing or non-rated fittings that leak or blow under pressure.
• Ignoring moisture in the air system, which can freeze valves in winter.
• Overtightening carrier caps without following the cross-pattern sequence.
• Engaging the locker at speed on pavement, which can stress drivetrain components.

Tips for a Trouble-Free Install

• Photograph each step before disassembly so you can match orientation at reassembly.
• Label every air line and wire at both ends.
• Keep spare fittings and a few feet of tubing in your recovery kit.
• Plan the install for a dry day with good lighting, and keep the work area clean.
• If you are not confident setting gear mesh, have a qualified driveline or axle specialist verify the work.

Recommended gear

A dial indicator set with a magnetic base is the most useful measuring tool for checking ring gear backlash accurately, which the locker manufacturer will specify. Look for a kit that includes a stable base and a fine-reading indicator.

Gear marking compound helps you confirm tooth contact pattern before final assembly, reducing the risk of premature gear wear. View on Amazon

A calibrated torque wrench in the range your axle requires ensures ring gear bolts and carrier caps are tightened correctly, which matters for both safety and gear life. View on Amazon

Moisture filter inserts for compressed air lines help keep condensation out of the solenoid and actuator, especially in cold climates where water can freeze inside valves. View on Amazon

FAQ

Can I install an ARB air locker kit myself?

Many experienced home mechanics complete this job with a good service manual and the right tools. Gear setup, backlash, and preload are precise tasks, so if you have not set ring and pinion gears before, consider having a qualified axle shop verify your work.

How long does the install usually take?

Time varies widely with experience, shop setup, and whether you are also replacing gears. Plan for a full day or more for a first-time install, including testing.

Does an air locker need to be engaged all the time?

No. Air lockers are designed to be engaged when needed and released for normal street driving. Running locked on pavement increases tire scrub and drivetrain stress.

What fluid should I use after installation?

Use the differential fluid type and quantity specified for your axle and locker. Some setups call for a specific friction or lubricant additive, so check the instructions before filling.

Why does my locker not engage?

Common causes include low air pressure, a blocked or leaking line, a wiring fault at the solenoid, or a failed valve. Start by checking pressure at the actuator, then test power and ground at the solenoid with a multimeter.

How do I know if my air supply is sufficient?

Confirm the system holds pressure within the actuator’s rated range during repeated engagements. A tank or compressor that struggles to refill between lock cycles is undersized for the job.

Is professional installation worth it?

For many owners it is, particularly when gears are changed at the same time. Gear setup errors can cause premature failure, so consider professional help if you are unsure about any measurement. Consult a qualified axle or driveline professional for guidance specific to your vehicle.

Conclusion

A well-installed arb air locker install kit delivers reliable lockup when you need it most on the trail. Verify compatibility, set up your air supply properly, and take the time to check backlash and contact pattern before you close the housing. Test thoroughly before your first serious outing, and recheck fasteners and fittings after break-in.

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