Overview
The ARB RD109 is an air locking differential for Dana 44 front or rear axles, with 35 splines and a 3.92 ratio up. It is a selectable locker, so the driver can switch between an open differential and a locked one.
The ARB Air Locker is a pneumatic locking differential that uses air to lock both axles. When it is engaged, the open differential works as a full spool, which the brand says sends power to both wheels in rough terrain. It needs an ARB onboard air compressor to operate.
Key features
- Pneumatic selectable locker
- Converts an open differential to a full spool when engaged
- Dana 44 axle type
- 35 spline axle spline count
- Needs an ARB onboard air compressor
Air locker setup considerations
An air locker changes how the axle shares power, so the decision to add one should follow the way the vehicle is used. On the trail, a locked axle keeps both wheels driving when one loses grip, which helps on steep climbs and off-camber sections. On the street, the locker should be disengaged, because a locked axle makes the vehicle hard to turn at low speed and can cause tire scrub on tight corners.
Gear work comes first. The locker needs gears matched to its spline count and ratio, and a gear shop normally sets the gear mesh and pinion preload after fitting. Plan the air system at the same time. The compressor, air lines, switch and wiring need a mounting location that keeps them clear of heat, mud and moving parts. Check the air lines and fittings for leaks after installation, and test the locker on a safe, low-speed surface before heavy trail use.
Specifications
| Brand | ARB 4×4 Accessories |
|---|---|
| Part number | RD109 |
| UPC | 881348006707 |
| Axle type | Dana 44 |
| Axle spline | 35 splines |
| Ratio | 3.92 ratio up |
| Differential type | Selectable locker, air operated |
| Axle location | Front or rear |
Vehicle fitment
This is a Dana 44 axle part. Check the axle spline count, ratio and housing against your axle before ordering.
Confirm your vehicle’s year, model and trim before ordering.
Installation notes
Air lockers are typically installed by a qualified gear shop, which sets gear mesh and pinion preload. The air compressor is a separate installation.
What’s included
The air locking differential unit.
Not included: the ARB onboard air compressor, which is needed to activate the locker.
