Lock both axles and the JK becomes a different machine on rock — traction is no longer a question of luck or momentum. The rear lock is the higher-priority install; the front matters most when you're on off-camber ledges or loose boulder fields.
The JK's axle configuration splits by trim. Non-Rubicon JKs get a Dana 30 front and Dana 44 rear. Rubicon models come with Dana 44 front and rear plus factory electric lockers. If you have a Rubicon with functioning factory e-lockers, that's already the spine entry — you don't need an aftermarket locker unless the factory units have failed. For Sport, Sport S, and Sahara owners, both front and rear aftermarket lockers are on the table.
**ARB Air Locker (Selectable):** The cleanest option for a street-and-trail JK. When disengaged, the carrier behaves exactly like an open diff — no binding in turns, normal tire wear, no noise. Engaged via a dashboard-mounted switch connected to an ARB compressor, it locks both axle shafts solid. The tradeoff is complexity: you're adding a compressor, air lines, and a solenoid to the diff, which are additional failure points. The ARB is the right call for any build that spends significant time on pavement between trail runs.
**Eaton ELocker (Selectable, electric):** No compressor required — the lock engages via an electric actuator wired to the cab. More straightforward than an air system, close to ARB's street behavior when disengaged, and proven across a wide installed base on Jeep applications. The ELocker engages at low speed only (under 15 mph for most applications) — not a limitation in trail driving but worth knowing.
**Detroit Locker (Full-time):** Locks automatically under throttle, unlocks briefly during deceleration to allow cornering. Zero complexity, zero maintenance, mechanical reliability. The cost is noise — Detroits clunk on-road during slow turns, and the engagement behavior can feel unpredictable to drivers who haven't used one before. The right call for a dedicated trail rig that rarely sees urban driving.
Install the rear locker first. In technical terrain, the rear axle is the primary driver — rear traction is what gets you up a ledge; front traction is what keeps the front from sliding off a line. A rear locker alone transforms the JK from a traction-challenged stock setup into a capable trail machine. Add the front when you're ready to tackle off-camber and boulder fields.
The Dana 44 rear on non-Rubicon JKs uses a 30-spline shaft — confirm this before ordering. Non-Rubicon Dana 44 rears (2007–2018) run a 3.73 factory gear ratio in most Sport/Sahara trims; Rubicons run 4.10. Verify your ratio before pairing with a regear order.
Locker installation requires setting ring-and-pinion backlash and bearing preload correctly — this is not a typical backyard install unless you've done differential work before. Plan for 6–8 hours with a bearing press and a methodical approach to pattern reading, or budget for a shop that does axle work regularly (not a general tire shop). Incorrect preload causes premature bearing failure; incorrect backlash causes gear noise and accelerated ring-and-pinion wear.
When installing an ARB Air Locker, run the air lines before buttoning up the axle. The most common post-install complaint is a kinked or chafed air line that develops a slow leak months later.
| Part | Vendor | Est. price |
|---|---|---|
| ARB Air Locker RD100 (Dana 30 front, 27-spline) | ARB | ~$699 |
| ARB Air Locker RD118 (Dana 44 rear, 30-spline) | ARB | ~$749 |
| Eaton ELocker Dana 44 Rear (2007–2018 JK) | Eaton | ~$689 |
| Detroit Locker Dana 44 Rear (2007–2018 JK) | Detroit Locker | ~$549 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.