4x4 Lockers: Better Traction For 4x4 Trucks - Get A Grip

Selectable Lockers
ARB Air Locker: ARB has been offering air-actuated lockers since the mid-1980s, and the company has at least two patents on the product. The design has proven to be reliable over the years, and has been tested in high temperatures, low temperatures, against high wheel inertia, and in the field against dust, dirt, and hard overall use. There are applications for almost every 4x4, and UTVs as well. They are manufactured by ARB in Australia and are currently in use in over 80 countries throughout the world.

High-performance competition models are available for use with high-traction tires, hardened axles, and intensive torque loading. Used in drag racing, rockcrawling, and tread-type snow machines, these units employ more exotic materials to assure that they will be stronger than the axles they turn.

The ARB locker does require an air source to operate the locking mechanism. This can be a huge advantage, and in some cases, a disadvantage. By adding a compressor, the ARB mechanism assures an air supply--something every well-engineered 4x4 should have. The compressor also adds cost, but again, it's a cost that would be part of the buildup of a proper off-road-trail-going 4x4. The downside is that because the ARB is air-dependent, should an air line be torn away, or a coupling leak, then the locker will not work. These events are not unheard of in the context of intense four-wheeling, so it makes sense to carry an air line repair kit in the toolbox, just in case. ARB offers a variety of compressors to go with the Air Locker, with a range of price points.

From a performance point of view, the ARB is a true locker that, like other selectable lockers, does not affect handling or create driveline wear when not engaged. That makes it suitable for use in the front differential, as well as the rear. Hardcore rockcrawlers we know like it in the front, because they can actuate it in a particularly difficult spot, gain traction, then click out of it after moving forward just a few feet to regain easy steering control.

Installation time and complexity vary widely, depending on the vehicle. A well-organized professional mechanic might be able to install an ARB in the front Dana 30 of a Jeep in three hours. The same guy might need the better part of a day to do the job on an IFS Toyota front axle. Nils, a tech at ARB, estimated that installation compares to those of other selectable lockers: "The only thing that would add time is you've got the air delivery system, which takes a little more caution, and you would be drilling and tapping for the air line." Tools for the job would include a dial indicator, a micrometer to measure shims to get the backlash right, and a case spreader is a good idea with any locker install. Nils says the install is "definitely feasible for the average mechanic in the home garage," but the amount of time "will depend on how organized your toolbox is."

Eaton ELocker: The electronic ELocker is a selectable locker that has been a long time coming as an aftermarket product. "They were originally developed in 1999 for AM General on the OE side of our business," said Eaton engineer Jeff Saxton, "as a pin-style device where there is a series of pins that pin one of the side gears to the case. It gives you a very simple and very durable unit. Then as we started to broaden the product line into smaller axles, we saw that you could not just scale down that type of design into the smaller axle cases and maintain the same level of durability."

That meant that Eaton had to develop a new electronically locking product for smaller axles, which is now called the "collar-style" ELocker. "Instead of using pins that drive through the flange of the case, we use these locked rings that are actually internal to the case. That allowed us to make the whole package smaller and maintain the type of durability we were looking for."

The newest applications, for the Dana 30 and 35 axles with both 27- and 30-spline axleshafts, were some of the hardest to engineer. "We originally attempted to do a two-pinion design, and simply could not get equivalent durability out of it. So we had to take a step back and ultimately go to a four-pinion design. That meant we had to extend our development time, but we felt that would be better than compromising the product."

According to Saxton, the move to a four-pinion, collar-style electronic locker has made a huge difference in strength and reliability. "Our ELockers are the most bulletproof out there," he told us. "I would not go so far to say it is as strong as a Detroit Locker. You're still looking at a traditional differential design with pinion shaft and pinion gears. Whereas a Detroit distributes the same load on far, far greater surface areas. But the flip side of that is the selectability. We developed the Elocker to give the driver selectability in its use."

The ELocker delivers the torque-biasing performance of a true locking differential. As long as the wheels are turning at the same rate (within 50 rpm) it can be actuated at speeds of 20 mph and below; otherwise, the maximum engagement speed would be about 5 mph. The ELocker can be used when operating in 2-Hi, 4-Hi or 4-Lo. Because it returns the differential to an open state when deactivated, it is suitable for use in front, rear, or both axles. The ELocker is maintenance free, requiring no special lubrication additives, and it is compatible with ABS and vehicle stability control systems on newer 4x4s. Unlike the ARB Air Locker, there is no air supply requirement, but you do have to wire the locker to a switch. The assembly kit includes the switch and wiring.

Auburn ECTED: Auburn Gear produces a full line of differentials for Chrysler, Ford, GM, and Toyota vehicles, all compatible with ABS and OEM electronic control systems. The company has been in business for nearly 50 years in Auburn, Indiana. They also offer spools, mini- spools and a wide variety of service kits. Ralph Traycoff at Auburn Gear told us that the ECTED is typically purchased by off-road enthusiasts looking for true locking differential performance. "I think the best setup depends on what you're using it for," Traycoff told us. "If you're towing a boat, maybe a limited slip is best. For a serious Jeep, it's the ECTED. For drag racing, you want a spool."

According to the company website, the Auburn ECTED locking differential is a selectable unit that can operate as a limited slip when not engaged. When it is engaged, it becomes a full-locking differential. Although it uses a dash-mounted switch to actuate as a locker like the ELocker, the internal design is different. Inside, there is a clutch pack that provides the limited-slip mode. As torque increases, the clutch pack is compressed and the differential begins to bias torque to the high-traction wheel. To get true locking performance, the driver actuates a switch that electrically causes a ball-and-ramp arrangement to engage a center pin that ultimately compresses the clutch pack and gives the user a solid axle assembly. There are no shift forks or pins that have to line up to move into the locker mode; Auburn sources say it can be switched on or off at most any speed. Like other selectable locking differentials, it is quiet and can be used in front axles with or without lockout hubs, although the ECTED is not recommended for use in front axles that have an inter-axle disconnect, like the Jeep Cherokee XJ. The internal gearing is made from 9310 heat-treated billet steel. The warranty is for one year, and the unit is backed by a replacement/exchange program.

OX Locker: This is a selectable locker that can be actuated by any of three modes--cable, air pressure, or a switch that activates a remote-mounted electrical actuator via a short cable. The actuation occurs when the cable moves a fork mounted in the OX differential cover. The fork actuates a locking ring that moves into a locking side gear. "It's actually the same concept as an ARB," according to Chip Keckler at OX Lockers. The internals (carrier case, forks, and rings) are heat-treated for durability and all are made in the USA. The side gear is not straight-cut, but back-cut, so it looks like a dovetail joint when engaged, making an extremely positive connection. "We probably have the strongest selectable locker on the market," Keckler said. The flip side of that is you have to unload the system to get back into open mode, either by taking your foot off the accelerator or otherwise unloading the system from torque.

Installation is going to be about the same as any other locker, except that routing and adjusting the cable takes some thought, as it should not be exposed to heat or abrasion. When actuated using an air line, any 100psi source of air pressure can be used.