Air Lockers
Air differential lockers, such as those offered by ARB, are one of the most popular locking differentials on the market today. These drivetrain components allow a vehicle to run with an open differential when wanted, and locked when needed. This makes them exceptionally versatile. ARB Air Lockers feature precision manufacturing with premium parts for the most demanding off-road situations. With forged gears, billet-machined components, a hardened cross-shaft retaining pin, and a fully machined one-piece nodular iron diff carrier case, ARB Air Differential Lockers are built tough.
Air lockers use compressed air to engage (or lock) the differential. This air originates from an on-board compressor, such as those offered by ARB. The air is fed through an air line to the differential’s seal housing. The air goes behind a bonded seal which then pushes on a clutch locking the side gear, thus all the gears get locked. This locking is what gives the equal 50-50 power split to a locked differential.
When the air compressor is turned off, the air is released, a wave spring pushes the locking gear back into place, and the differential becomes open again, providing a driving experience just like you’d get from the OEM. Unlike some other kinds of differential lockers, ARB Air Lockers can be engaged at any speed, which can be a benefit for those using a diff locker at higher speeds, such as desert travel.
In terms of setup, this system requires wiring the air compressor and a switch to operate it. The switch should be located near the driver so they can easily reach it. Air lockers also require plumbing an air line to the differential. Since the original factory differential needs to be removed and replaced, we recommend using a professional who is experienced with ARB Air Locker installation to perform the work.
ARB Air Differential Lockers are exceptionally strong, offering up to 40% more strength than an open differential. All ARB Air Lockers also include four spider gears; some lighter duty open differentials only use two. Additionally, the two-piece machined case is exceptionally strong, making these drive train parts ultra reliable. Air lockers are mostly mechanical except for the air compressor system. ARB uses high-quality fittings and couplers to prohibit air leaks as well.
The combination of strength, easy selectability, and proven reliability make ARB Air Lockers a top choice for off-road enthusiasts and racers alike. ARB Air Lockers can be found on off-road vehicles around the world.
Electronic Differential Lockers
Electronic lockers (aka “e-lockers”) don’t use air to lock the differential, instead, they rely on electric motors, solenoids, and/or electromagnets. Through electric actuation, pins or plates are slid to a side gear to engage and lock the differential vs. an air locker’s air pressure. Like an air locker, however, they require the push of a button or switch to engage and disengage.
E-lockers don’t require an on-board air compressor but do feature far more complex electronics than an air locker setup, which is mostly mechanical. It should be noted that most OEM-supplied locker systems employ e-lockers.
Many e-lockers must be engaged at or below relatively low speeds and may not be as robust as an aftermarket ARB Air Locker. And while, there are no air hoses or fittings that can leak on an e-locker, there is more potential for electrical complications or failures, which can compromise reliability, especially on aftermarket e-lockers.
Setting up an e-locker is like an air differential locker in the fact you’re replacing drive train parts. In this instance, again, it’s the entire differential, and therefore you need to set your gears up again. Like other vehicle transmission and drivetrain parts, having a knowledgeable professional do the work is highly recommended.
Mechanical Differential Lockers
Mechanical differential lockers, sometimes called auto lockers, are often a lower-cost, simple way to add a locker to a vehicle. However, they have one major caveat: they’re not selectable. This means they can be somewhat unpredictable, especially on slippery surfaces such as snow and ice, or when executing tight turns.
When you add a mechanical locker, they usually do not require you to replace the differential carrier or other drive train parts. Mechanical differential lockers include several parts and are usually composed of two couplers with teeth, two drivers with corresponding teeth, two spacers, pins, and springs. Once assembled, the auto locker replaces the spider gears. The diff’s original carrier center pin will often be reused and go through the center.
Auto lockers are always locked in a straight line with the coupler and driver teeth firmly meshed together. But when you turn your vehicle and one axle needs to rotate at a different speed, they allow for some slip, as the coupler and driver disengage creating an open-differential scenario. While turning, however, you’ll notice clicking or ratcheting noises, so they can be noisy. Once you straighten out, the teeth will mesh together again, locking the differential once more. Additionally, when the teeth come together again, they can make a loud bang or clunk. Sometimes when turning, the diff won’t fully disengage, resulting in tire chirping on pavement.
Mechanical differential lockers are less expensive drive train parts than air differential lockers or e-lockers, but don’t offer the ability to select open or locked, and they can be noisy and somewhat unpredictable depending on the conditions.
Manual Differential Lockers
Manual differential lockers work similarly to e-lockers, but instead of using motors or solenoids to lock the differential’s side gears, it uses a cable actuated system. While they don’t rely on electronics, they require routing cables and modifying cable tensions and lengths. There may also be springs to deal with and rods/levers to adjust. So, while you don’t have to worry about electrical, you do have to be concerned with several manual adjustments to the system.
Spools
A spool is the simplest form of a locking differential as it has the axles locked 100% of the time, meaning they aren’t selectable.
There are full spools and mini spools. A full spool replaces the entire differential including carrier, spider gears, and side gears. A mini spool retains the factory carrier but replaces the spider and side gears. In terms of drive train parts, a mini spool is usually the simplest and cheaper of the spool options.
Regardless of which spool gets installed, they keep the left/right axles at a 50/50 split all the time. And since there’s no open differential scenario allowing the axles to turn at different rates, when cornering, there will be tires chirping on pavement as the axles cannot compensate for the axles which need to spin at different speeds. Therefore, it’s the tires that give. Spools are generally best for off-road use only. Since the axles are locked all the time, spools can be hard on axles and tires alike.
Without a doubt, spools are the easiest way to have a locked rear differential. However, they come with a lot of compromises regarding drivability.
Which Differential Locker is Right for You?
No matter which kind of differential locker you purchase, there’s a fair bit of setup and installation time required since you’re digging into the axles. While there are varying degrees of complexity to all lockers and power train parts, selectable diff lockers offer the greatest versatility and performance ability. They can conveniently be used on- or off-road and provide both open and closed functionality. ARB Air Lockers are tried and tested products with decades of engineering know-how built in. ARB Air Lockers are used around the world by off-road enthusiasts and racers alike. Strong, reliable, and easy to use, ARB Air Lockers should be at the top of your list when looking at adding aftermarket differential lockers.
