Rear Locker Options — Dana 35 and Dana 44

The axle situation on the JL is the critical starting context. JL Sport and Sport S models come with a Dana 35 rear axle — a solid, competent axle for street and mild trail use, but lighter-duty than the Dana 44. The Sahara also ships with the Dana 35 in most configurations. The Rubicon (and the Rubicon 392) gets the Dana 44, which is the significantly stronger choice for technical trail use. If you're on a Sport or Sahara and considering a locker, you need to decide whether you're locking a Dana 35 long-term or upgrading to a Dana 44 carrier down the road — because the lockers are not interchangeable.

For the Dana 35 (Sport/Sahara), the two realistic choices are the ARB Air Locker ($799) or the Detroit Truetrac ($449). The Truetrac is not technically a locker — it's a helical gear limited-slip differential that provides significant bias toward the wheel with traction under load, but does not achieve full lock. For mild-to-moderate trail use on a rig that sees pavement regularly, the Truetrac is the right choice: it's transparent on-road, requires no compressor or electrical system, and the $449 price point is accessible. For genuine rock crawling where complete drive wheel lock is required, the Truetrac falls short.

The ARB Air Locker for the Dana 35 ($799) delivers full lock on demand. ARB's air locker engages via an onboard air compressor (required separately — budget $150–$300 for a basic unit) and disengages cleanly when the air is released. The on-road behavior when unlocked is stock-equivalent. The ARB is the correct choice for a Dana 35 build that sees sustained technical terrain. be realistic: a Dana 35 with a locker will eventually meet a trail that exceeds the axle's shaft strength. Know your terrain.

For the Dana 44 (Rubicon), both the ARB Air Locker ($849) and Eaton ELocker ($649) are full-lock solutions with different engagement mechanisms. The ARB requires a compressor; the Eaton ELocker engages electrically via a dash switch. The ELocker is the value choice for a Rubicon build — $200 less than the ARB, no compressor required, reliable engagement, and the electrical install is cleaner. The ARB's advantage is faster engagement response and the ability to share the compressor with ARB lockers front and rear, plus tire inflation duties.

Rubicon owners note: the factory Selec-Trac II transfer case includes an electronic rear locker. If your Rubicon already has the factory locker, evaluate whether an aftermarket locker adds meaningful capability before spending $649–$849.

Steps

1. Drain the differential fluid before any disassembly.
2. Support the rear axle on jack stands and remove both rear wheels.
3. Remove the rear brake drums or caliper/rotor assemblies (depending on trim) and disconnect the axle shafts.
4. Mark the bearing caps before removal — they are directional and must return to the same position.
5. Remove the carrier bearing caps and extract the ring gear/carrier assembly.
6. Transfer the ring gear to the locker carrier per manufacturer instructions. New ring gear bolts should be used — old bolts stretch and should not be reused.
7. Set ring gear backlash and bearing preload per manufacturer specs using a dial indicator. This step requires patience and is the most critical part of the install — incorrect backlash causes noise, premature wear, or failure.
8. For ARB: route air lines through the axle housing per the included instructions before reinstalling carrier.
9. Reinstall carrier, torque bearing caps to spec.
10. Reconnect axle shafts, reinstall brakes, reinstall wheels.
11. For ARB: mount the air compressor, route air lines to the cab switch per install instructions.
12. For Eaton ELocker: route electrical harness to the cab switch location per install instructions.
13. Refill differential with gear oil per manufacturer's fluid spec — some lockers require specific viscosity.
14. Test locker engagement off the vehicle before returning to trail. Drive slowly, confirm engagement and disengagement.

Why it works

• A rear locker delivers the most direct off-road capability gain of any single JL upgrade — full traction to both rear wheels in a bind
• ARB Air Locker is the gold standard for on-demand, full-lock engagement with stock-equivalent on-road behavior
• Eaton ELocker delivers full lock at lower cost than ARB with no compressor requirement
• Detroit Truetrac is the right answer for a Dana 35 on a mild-trail rig that sees significant pavement
• ARB compressor (required for air locker) doubles as a trail inflation tool — functional overlap

Trade-offs

• Dana 35 (Sport/Sahara) is a lighter-duty axle than the Dana 44 — a locker increases the load on the axle shafts, which are already the weak point; know your terrain limits
• ARB Air Locker installation requires a compressor and plumbing, adding cost and complexity beyond the locker itself
• Setting ring gear backlash correctly requires a dial indicator and specific knowledge; this is not a beginner install
• Incorrect carrier bearing preload will cause differential noise within the first few hundred miles — don't skip the setup spec steps
• Eaton ELocker is not available for the Dana 35 — Sport/Sahara owners are limited to ARB or Truetrac
• Rubicon's factory electronic rear locker may make an aftermarket locker redundant — evaluate factory capability before purchasing

Tools required

• floor jack
• jack stands
• socket set
• torque wrench
• bearing puller
• dial indicator
• ring gear setup tools
• inch-pound torque wrench

Parts

Sources

• ARB Air Locker Product Overview
• Eaton ELocker Installation and Specs
• Detroit Truetrac Dana 35 Product Page

Related

• Re-Gearing the JL — 4.56 and 4.88 Ratio Selection
• All Jeep Wrangler JL guides & tools
• Browse the full DIY database

Written and maintained by an AZ wheeler and driveway wrencher. How we source guides. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.