How an Open Differential Operates
When considering whether to use a locking differential, it is important to understand the difference between a locking differential, or a standard open differential. Many stock street vehicles are designed with an open differential. Its job is to transfer power from the engine to the axle at different speeds. Alternating the speed and power allows the wheels to spin faster or slower than the other. This is ideal when cornering to avoid tire squeal and drag because while taking a corner, the distance each wheel is required to travel varies due to the arc of the curve on the inside versus the outside of the corner. Since the wheels are connected to the same axle housing, the outside wheel must travel faster to keep up with the inner wheel cornering in a smaller arc. On the occasion when traction between the tire and the ground differs from one side of the vehicle to the other the tire encountering less friction and less traction will have more power transferred to it. Since cornering and traction differences from side-to-side are some of the most frequent on-road driving issues, most two-wheel driven vehicles are equipped with an open differential. An open differential also costs less, which, when paired with its suitability for common road travel, makes it the most prevalent stock option for two-wheel driven vehicles and many four-wheel-drive vehicles.
What Locking Differentials Provide While Off-Road
A locking differential also transfers power from the engine to the axle, but it allows the wheels to travel at the same speed. In the case of lost traction, when one wheel has traction, and the other doesn’t, both will be spinning at the same rate regardless of resistance. Imagine crawling up on a trail, and you get hung up on one side from a rut or some seriously uneven terrain, and the opposite tire is spinning in the air. With a locking differential, power will be transferred to both tires, allowing the tire with traction to pull your rig up and out. In the same scenario with an open differential, power would be transferred to the spinning tire, not to the tire that still has contact and traction. Now you are hung up, with a lot of power going to the tire hanging in the air, not the one that has the traction to get you out and on your way. A locking differential will transfer the power equally to both wheels allowing the wheel that still has contact to pull your rig forward. Since getting hung up on a rock or stuck in a low spot is all too common, and part of the fun of off-roading, locking differentials have become a primary modification to trucks and other 4-wheel drive vehicles looking for some good times out on the trails.
Types of Lockers
Now that you have decided to get your 4x4 ready for the trail by upgrading to a locking differential, it’s time to consider which type you will use and on which axle, or both.
One option is an automatic locking differential. These do just what they say; they lock or unlock automatically without needing input from the driver. Within the category of automatic locking differentials, there are also sub-categories of full-time lockers which are locked under most circumstances (but unlock at times when certain conditions are met) and those that are usually open (and lock when necessary).
A Detroit locker is a great example of a full-time automatic locker. This locker remains in a locked position until stimulated by external conditions that require the wheels to spin at different speeds. While this is an excellent system to have in place on the trail, it can cause some occasional loose handling back on the streets, especially on vehicles with a short wheelbase.
Automatic lockers will provide your vehicle with better crawling capabilities out on the trail and can be a wallet-friendly option if you are looking to put them on a trail only vehicle. However, because they are reactionary, you as the driver will be subject to the will of the forces acting on the locker and may experience some loose driving, clicking noises when the locker is disengaged, and added stress to your vehicle. If you are wanting to add some trail skills to your daily 4-wheel drive vehicle and remain in control of when the locker is engaged, a selectable locker will provide that.
If you are looking to get all of the benefits of a locking differential without adding undue stress to your rig, or the untimely surprise of squirrely handling, selectable lockers are a great option. Selectable lockers (also known as manual lockers) usually cost more than automatic lockers. However, they are more durable and have fewer drawbacks than automatic lockers. They also put the control totally in the hands of the operator. As with automatic lockers, there are also a couple of different styles of selectable lockers to fit your needs.
Air lockers work using a compressed air system that locks the differential with the push of a button installed in the cab. When initiated, the pneumatic locking system stops the gears from rotating, which locks the differential. The differential remains in the open position unless it is activated. As mentioned earlier, an automatic locking differential system has some drawbacks when using it to enhance the capabilities of your daily driver. With a selectable air locker, like an ARB Air Locker, you will be able to choose when to engage the system. If you decide to use a selectable air locker to upgrade your vehicle’s performance, be sure to have it properly installed to avoid unnecessary and costly problems.
Similar to air lockers, electronic lockers (sometimes referred to as e-lockers) only requires the driver to push a button to activate the differential lock. Once the lockers are engaged, power is transferred evenly between the wheels to maximize off-road performance and rock crawling abilities. In short, a selectable locker provides you with a quality ride on the streets and the ability to conquer rocks on the trail.
Overall Benefits of Locking Differentials
Automatic lockers are generally less expensive, easier to install, and will beef up your vehicle’s trail capabilities. However, they can create loose handling situations on the street and cause additional wear on your rig overall.
Selectable lockers give the driver total control, allow for better adaptation between road and off-road use; and although they generally cost more and are more complicated to install or fix, the reduced stress on your vehicle can save you money and headaches in the long run. Check out ARB Air Lockers and Yukon Grizzly Lockers if you go this route.
Whether you choose an automatic or selectable locker, you will benefit from the following:
Even power distribution to the wheels
Improved off-road performance
Better traction in rough terrain
Can modify either axle or both
Ease of use either automatically or with the push of a button
Visit OK4WD.com to find the one that works for your rig.