The Off-roading Benefits of a Locking Differential

Open Differential

Open differentials counteract the wheel-hop associated with a locking differential, using a series of gears that allow each wheel to spin independently. On the street, an open differential allows your vehicle to take sharp turns without the inboard wheel hopping/skipping.

In instances of low traction or extreme articulation, an open differential diverts all power to the wheel with the least resistance/traction––not ideal for off-road usage. In practice, if one of your ride’s wheels is in the air on a challenging obstacle, all power is sent to the wheel with the least resistance––in this scenario: the wheel that isn’t touching the ground. With no power being sent to the wheel making ground contact, you’ll sit there all day long, spinning.

Limited-Slip Differential

Limited-slip differentials combat the traction issues caused by an open differential, utilizing a series of clutches that engage and disengage depending on traction. Around corners and in situations with ample traction, the limited-slip differential operates just like an open differential, allowing both wheels to spin independently to prevent wheel hop. 

However, in instances with limited traction, the clutches within a limited-slip differential engage to send power to the wheel with the most traction. During mild off-roading, a limited-slip differential allows your vehicle to conquer most obstacles; however––like the clutches in a transmission––clutches in a limited-slip differential are prone to wear. When your limited-slip differential’s clutches begin to slip, traction is no better than an open differential. 

Locking Differential

Locking differentials are tough-as-nails and uber-effective on the trail. Unlike the previous two differential types, locking differentials form a physical connection between both axle shafts when engaged, sending 100 percent power to both wheels, 100-percent of the time. 

While lockers may lead to hopping, skipping, chirping, and uneven tire wear on the street, off-road traction is unmatched. No matter the conditions––whether in ice, snow, sand, mud, or with three or fewer tires on the trail––locking differentials put power to the ground.

Styles of Locking Differential

Locking differentials come in a few different flavors; let’s take a look at the three most common varieties: selectable, automatic, and spool.

Selectable

Selectable locking differentials allow operators to manually choose when the locker is engaged using either electric or pneumatic assistance. With an E-locker (electric), a magnet within the differential attracts a series of bearings or pins to join the two axle shafts. On the other hand, air lockers (pneumatic) use high-pressure air fed into the differential from an onboard air compressor, engaging an internal clutch gear that locks the spider and side gears together.

Both styles of locking differential operate just like an open differential when disengaged, allowing unhindered street driving. 

Automatic

Automatic M-lockers (mechanical) are even simpler, automatically engaging whenever necessary. During low-traction events, in which an RPM variance greater than the locker’s pre-set threshold is detected, automatic lockers tie your ride’s axle shafts together to maintain traction. 

On the street, automatic lockers exhibit poor driving characteristics compared to selectable lockers. While superior to a spool on the street, automatic lockers can cause some skipping, hopping, and uneven tire wear.  

Spool

While less street-friendly than the previous two styles of locker, full spools and mini spools are a popular choice among budget-oriented wheelers for their low price, simplicity, and traction benefits. Spools and mini spools both replace moving parts in the differential; however, they replace different components. Full spools replace the entire carrier, while mini spools are installed within a factory open carrier in place of the spider gears. 

With spool and mini-spool rear differentials, there’s no on or off switch; both axles are locked together 100 percent of the time, making street driving far less enjoyable. However, for a budget-minded dedicated wheeling rig, they aren’t a bad option to improve traction!

Is a Locking Differential Right for You? What Type? 

For the avid offroader, locking differentials are essential. No matter how extensive your ride’s modification sheet is, you can’t conquer obstacles without putting adequate traction to the ground.

A factory limited-slip differential will likely be sufficient for the daily driver that performs occasional mild wheeling. However, if you routinely struggle for traction on challenging trails, consider adding a locking differential to your wishlist; but which locker is right for you? 

Selectable and automatic lockers are both excellent choices for the street and trail; however, we’d recommend a selectable unit for a vehicle that racks up loads of street miles. Disengaged on the asphalt, selectable lockers operate just like an open differential, allowing for sharp U-turns and easier navigation through crowded parking lots. However, it’s important to note that a torn air line, blown seal, or shredded wiring harness will render a locking differential useless. 

On the other hand, mechanical lockers are ideal for applications that see more trail use than street driving. Unlike selectable lockers, mechanical lockers are completely self-contained; there’s no need for external wiring harnesses, air lines, or compressors. Fewer parts means less prone to failure, making automatic lockers best suited for hardcore wheeling. On the street, they’re also less efficient than selectable lockers. While not as noticeable as a spool or mini spool, automatic lockers will still exhibit some hopping and skipping on the street, necessitating some changes to your driving habits. 

Regarding spools and mini spools, we won’t ever really recommend them over a traditional locking differential; however, if you’re wheeling a cheap beater and need an inexpensive way to lock up your open differential, spools are more reliable than a Lincoln locker! 

RealTruck offers a wide selection of locking differentials for most applications. And as always, feel free to contact our knowledgeable sales team for any product inquiries or assistance making a purchase.