Differential Lockers: The truth about locking differentials
Locking 4x4 Diff Lock
“It doesn’t look too deep,” your passenger says, as your approach the harmless looking mud pudding in the middle of the trail. “Just go for it.” Ignoring everything you’ve read about off road driving and recovery, you switch into 4-Low and slowly drive into the murky pool. Ten seconds later you’re stuck, with one front and one rear wheel spinning helplessly. As you hand your passenger a shovel, you reflect on the obvious: you need a differential locker.
What is a differential locker, what does it do, and how does it work? Odds are if you drive a 4WD truck and are on this site, you have some idea of what a differential locker is. But even muddy 4WD veterans often get it wrong as there are many types of differential lockers. So to help clear the locking differential air, we’ve put together this differential locker overview.
Open vs Locked Differentials
Most vehicles have open differentials. This allows power to be applied to one wheel on the axle while the other wheel rotates independently. The idea is to improve on-road handling and cornering by allowing power to be applied smoothly while each wheel rotates at different speeds–such as when cornering. With a differential locker, the axles are essentially locked and power is applied to both wheels equally, regardless of traction conditions or wheel speed. So instead of one wheel spinning helplessly (the low traction wheel) both wheel spin equally. Off road, the traction improvement is stunning.
Types of Differential Lockers
For four wheelers, there are two main types of differential lockers: switched and automatic. A switched locker utilizes some kind of actuating switch–electronic, cable, air–to lock the differential only when extra traction is needed. When switched off, the differential remains open. Automatic locking differentials remained in a locked state until they automatically unlock around corners, to enable the wheels to rotate at different speeds.
Benefits of Differential Lockers
Traction, traction, and more traction: a locking differential can completely transform the off-road capabilities of any 4WD truck. By providing power evenly to both wheels regardless of the surface conditions, a locked differential provides enormous traction improvements. In tests, vehicles with locked differentials have performed better in 2WD than vehicles with open differentials in 4WD. (See Aussie Locker Evaluation)
Disadvantages of Differential Lockers
The main disadvantage of a differential locker is on the pavement: tire chirping around corners, some additional noise from the differential, accelerate tire wear, and different handling characteristics. With switched lockers, this can be avoided by simply disengaging the locker. Auto lockers utilize an auto-disengagement mechanism that unlocks in corners, but it’s not always silent or smooth.
Which Differential Locker is Right for Me?
That depends on how, where, and how often you drive your 4WD truck. Switched lockers can be expensive ($800-$1500) and must be precisely installed. They also have extra components–wires, air lines, switches, compressors, cables–that can potentially be damaged in extreme off-road conditions. Auto differential lockers are often much cheaper ($150-$500), can be installed by the backyard mechanic, and have no external components making them very robust and maintenance free with all the traction advantages of a switched locker.
Whichever locker you decide on, remember the Golden Rule of Differential Lockers: You will still get stuck, you’ll just get stuck a lot worse and further from home. 4WD trucks with differential lockers have such vastly improved traction, they can get you into even more trouble off-road. So use your locker wisely and remember you always need to be able to get back. And no off road modification replaces driver skills, knowledge, and respect for the trail.
