Lockers vs. Limited Slip Differentials for Jeep: A Complete Comparison

Most Jeep Wranglers leave the factory with open differentials in both axles (unless you opted for the Rubicon, which comes with factory electric lockers). An open differential sends power to the wheel with the least resistance. On pavement, this works perfectly because both tires have equal traction. Off-road, it is a liability.

When one tire loses traction, whether from mud, loose rock, or a wheel lifting off the ground during articulation, the open differential sends all engine torque to that spinning wheel. The tire with traction receives zero power. You can have a 450-horsepower engine and it will not matter if all that power is spinning a single tire in the air. This is why you see stock Jeeps with one wheel spinning wildly while the other three sit motionless on the ground. Electronic traction control helps by braking the spinning wheel, but it is a reactive, imprecise solution that reduces power and overheats brakes during sustained off-road use.

A locking differential mechanically locks both axle shafts together so they rotate at the same speed regardless of traction conditions. When engaged, power is delivered equally to both wheels, meaning the tire with traction can drive the vehicle forward even if the other tire is completely off the ground.

There are three primary types of lockers. Selectable lockers like the ARB Air Locker and Eaton E-Locker can be engaged and disengaged by the driver. The ARB uses compressed air from an onboard compressor, while the Eaton uses an electromagnetic mechanism activated by a dash-mounted switch. Both allow you to run an open differential on the street for normal driving behavior and lock the axle only when off-road traction is needed.

Automatic lockers like the Aussie Locker, Spartan Locker, and Lock-Right replace the spider gears inside the differential carrier with a locking mechanism that automatically engages under load and unlocks during turns. They are affordable and simple to install, but they produce clicking noises on the street and can cause unpredictable handling in corners on wet pavement because the locker does not always disengage smoothly.

The factory Rubicon lockers are electric selectable lockers built into the Dana 44 axles. They are reliable and well-integrated with the vehicle electronics but are limited to the Rubicon trim. Retrofitting Rubicon lockers to a non-Rubicon JL requires axle swaps and wiring modifications.

A limited slip differential (LSD) sits between an open differential and a full locker in terms of traction capability. Instead of locking both axle shafts solid, an LSD allows some speed difference between the wheels while transferring a portion of the torque to the wheel with better traction. This provides improved traction over an open differential while maintaining more predictable and comfortable on-road manners than a full locker.

The Eaton Truetrac is the most popular gear-driven LSD for Jeep applications. It uses a helical gear mechanism that progressively transfers torque bias based on resistance. When one wheel starts to slip, the Truetrac redirects up to 3.5 times more torque to the gripping wheel. It operates silently, requires no maintenance beyond normal gear oil changes, and never needs adjustment.

Clutch-type LSDs like the factory Trac-Lok found in many non-Rubicon Jeeps use friction clutch packs to limit wheel speed differences. These work well when new but the clutch packs wear over time, gradually reducing the LSD's effectiveness. Adding a friction modifier additive to the gear oil can extend clutch pack life, but eventually the unit will function like an open differential and require rebuild or replacement.

If you can only afford one locker or LSD, install it in the rear axle first. The rear axle carries more of the vehicle's weight (especially when loaded with gear) and handles the primary driving force during normal operation. A rear locker dramatically improves traction in most off-road situations, including climbing, descending, and navigating rutted trails.

A front locker provides additional benefit on severe terrain where both axles need to pull simultaneously, such as rock crawling, deep mud, and extreme articulation situations. However, a locked front axle significantly increases steering effort and can cause understeer on hard-packed surfaces. Selectable lockers are strongly recommended for the front axle so you can unlock for normal trail driving and engage only when the terrain demands it.

The ideal setup for a serious trail Jeep is a selectable locker in the front and either a selectable locker or automatic locker in the rear. The rear locker stays engaged most of the time off-road, while the front is engaged only for the hardest obstacles. A Truetrac LSD in the rear combined with a selectable locker in the front is a popular and practical combination for Jeeps that split time between trail and street.

Installing a locker or LSD requires removing the differential cover, extracting the carrier, and either modifying the existing carrier or replacing it entirely. Selectable lockers like the ARB and Eaton require additional components: the ARB needs an onboard air compressor, air lines, and a dash switch; the Eaton E-Locker needs wiring and a switch.

Automatic lockers and the Truetrac LSD are simpler because they replace internal components without external hardware. A Spartan Locker or Aussie Locker can be installed for under $300 including parts and gear oil, making them the budget king for traction improvement. A Truetrac runs $300 to $500 for the unit plus installation. Selectable lockers range from $800 to $1,500 per axle for parts, plus installation labor.

Many Jeep owners combine a regear with locker installation to save on labor costs, since both jobs require opening the differential. This is the most cost-effective approach and ensures the ring and pinion setup accounts for the new locker carrier.