What Is a Locking Differential?Last Updated August 8, 2023 | Alison Smith
Locking differentials (or “lockers”) are a mechanical feature that "locks" both wheels on an axle together so they travel at the same speed. When traction is lost for one wheel, all available torque is sent to the wheel with traction.
Most vehicles are equipped with an open differential, which allows the wheels to spin at different speeds while cornering. Typically, the wheel experiencing the least amount of traction will receive the most power.
Types of Locking Differentials
There are two main types of locking differentials: automatic and selectable.
Automatic locking differentials are exactly what they sound like: Diffs that lock automatically without requiring the driver to do anything.
Some automatic lockers, or full-time lockers, only unlock depending on the driving conditions, meaning that the diffs are locked at all other times. Other auto-locking diffs are the opposite, which means they only lock automatically when necessary. Lockers that only lock when absolutely needed will make the system last longer and prevent unnecessary tire wear.
Since automatic lockers don't let you have full control over your differential, they can be a bit awkward when driving on the road and put more stress on the vehicle and tires. They can also be loud when they lock and unlock, which can be annoying after a while. Unlocking and locking can also happen at random inconvenient times while driving. They are less expensive than selectable lockers, though.
The Detroit locker only has three ratchet gears and remains locked unless something forces the wheels to spin at different speeds. Because it's constantly in a locked position, the Detroit locker is great for off-roading and trailblazing, but it's not great for cruising or highway driving.
Be careful if you have a vehicle with a short wheelbase, too. Automatic lockers that remain in a closed position can be a bit dangerous or squirrelly when it comes to road handling.
Lunchbox lockers, also known as drop-in lockers, are an easy conversion option if you have an open diff. These lockers drop inside a factory differential carrier and replace the original stock spider gears. They're called lunchbox lockers because they're just a new component in the old diff housing.
When torque is applied, the lunchbox lockers will activate and allow even power distribution. They're relatively affordable, too since they don't replace the entire differential.
Selectable lockers let you switch between a locked and open differential freely. Electric lockers are more common in modern vehicles, but cable or air lockers will accomplish similar results.
Although selectable lockers, also known as manual lockers, are typically more expensive than automatic lockers, they will be more durable and cause fewer problems in the long run. Automatic lockers would be easier and cheaper to fix, though.
Having a selectable locker really makes your vehicle versatile enough to handle all your daily driving needs during the week as well as your off-roading excursions when Saturday rolls around.
Air lockers utilize a compressor system that can lock the differential with the push of a button. Upon activation, the pneumatic locking system stops the gears from rotating, thus locking the diff.
Unless the air locker is activated, the differential will remain in the open position. This is perfect for drivers with off-road rigs that double as a daily driver. However, if not installed properly, they can leak and cause various issues.
Electronic lockers, sometimes referred to as e-lockers, are similar to air systems as they only require the push of a button to initiate the diff lock. Basically, e-lockers send an electrical current that activates the locking system, closing the previously open differential.
For example, the Jeep Wrangler Rubicon features front and rear electronic locking differentials that can be initiated with the flip of a switch.
A cable-operated locker uses a cable-shifting system that’s connected to the locking mechanism. Typically equipped with a manual shifter, some can be converted to an electric switch.
While similar to air lockers, cables can be a bit more sturdy and durable. However, they can still be damaged if installed improperly or used incorrectly.
Related: Learn about limited-slip differential here.
Locking Differential Pros & Cons
|Distributes power evenly to the wheels||Higher cost for selectable lockers|
|Enhanced off-road performance||Tire chirping or barking when cornering|
|Improves traction in rough terrain||Clunky engage and disengage for automatic lockers|
|Can be equipped for the front axle, rear axle, or both||Can put added stress on driveline components if misused|
|Some can be activated with the push of a button||Selectable lockers can be complicated to fix if they break down|
|Selectable lockers are great for daily drivers|
Locking Differential Pros
Selectable lockers may provide more benefits than automatic diff locks, but either one is going to improve off-roading performance and capabilities when it comes to tackling tough obstacles on the trail. Here are a few reasons why you may consider investing in a locking differential.
Locking Differential Cons
While locking differentials will be beneficial to most people who plan on doing some wheeling, there are a few negatives to ponder. Selectable lockers, despite their higher cost, will offer more positives than automatic lockers. However, they are a bit more complex, which means that if a problem occurs, it will be a less straightforward fix than a simpler automatic locker.
Depending on how you use your vehicle, perhaps the standard open differential is all you need. But if you want a taste of the great outdoors and plan on doing quite a bit of off-roading, then you really can't go wrong with a locking differential!
What Vehicles Have Locking Differentials?
Because they're great for off-roading, locking diffs are often found on Jeep Wranglers, trucks, and other 4x4 rigs. They can also be added to the front, rear, or both axles of a vehicle with open differentials via aftermarket modifications.
If you're interested in upgrading your off-roader's axles, check out these parts: