The Best Off-Road Locker and Limited Slip: Four Wheeler Network Staff Picks
What is the best traction device for your off-road axles?
When it comes to lockers, limited slips, spools, and every iteration of traction differential in between, we've literally driven them all. And that includes the old-school stuff that isn't manufactured any more like a Willys Dana 25 Power-Lock limited slip or a low-pressure pneumatic TeraFlex T-Locker. Yeah, anybody remember those? We didn't think so. But with several decades under our belt doing hands-on product testing of virtually every new 4x4 product that comes to market comes a huge catalog of amassed information on things like "what is the best off-road traction device." And whether it's partially opinion, partially empirical, or partially undisputed fact, each Four Wheeler Network staffer has definitely developed their own thoughts on what our favorite traction differential is for off-road use. So, buckle up and take an off-road ride with one tire hanging in the air as the Four Wheeler Network staff lays out their favorite off-road differentials of all time.
Ken Brubaker: Eaton ELocker
I've found that choosing a locker or limited slip for an axle is a lot like choosing a cellphone. Some people want/need the latest and greatest whiz-bang tech, while others are cool with just a basic phone. And of course budget comes into play. That's why there's so many cellphones on the market. This reality carries over to the world of lockers, and there is a slew of different types available. Over the years, I've had 4x4s equipped with a number of different lockers and limited slips, and each has worked well, most of the time, in the vehicle they were in for the purpose the 4x4 was built. As time and technology has progressed, I've come to appreciate selectable lockers, and I've used said lockers with a variety of engagement methods. I'm a full-size 4x4 pickup fan because I need one rig that can do it all, including towing, hauling, trail running, mud navigating, and sand churning. For my needs, I want a beefy electronic selectable locker. I gotta go with the Eaton ELocker4. It's available for popular Dana axles and has a four-pinion design that bumps up the strength factor, and it has a super-fast engagement time of 0.14 seconds. Installation is slightly more involved than an automatic locker, but to me it's worth it.
Jason Gonderman: ARB Air Locker
Like many of my colleagues here, I've probably owned every type of locking or limited-slip differential available at some point, with the exception of two. I've never put a spool in anything or welded a differential. But there's still time for that. Of the ones I've owned, I think my favorite would be the ARB Air Locker—yes, ARB trademarked the term "air locker." I installed the very first available ARB locker for the Ford 9.75-inch rear axle many years back in a 2007 Ford F-150 that I own, and I had a JK Wrangler with a rear ARB locker for several years. I have always loved that when turned off, the ARB locker goes to an open differential, which gives fantastic street manors. Then, when it's locked, it's locked up tight with no slip. Sure, there's the downside of needing an air source to lock the differential, and there's always the chance of snagging a hose, but in my decade of running them I've never had an issue (knocks on wood). As a bonus, the larger compressors can be setup to air up tires or run tools, which is something the others can't do.
Christian Hazel: Spool, Detroit Locker, Eaton ELocker
This is a loaded question. Asking me to list my favorite traction device is like asking somebody who lives in the Arctic to describe snow. There are just too many variables to make one blanket statement. For me, it comes down to the vehicle, its intended use, and the wheelbase. All my vehicles, regardless of how modified or highly built, are driven on the street with relative frequency, including a welded rear Dana 60 in my Ramcharger that I commuted 250 miles a day on for over two years. With that caveat, here are my all-time top combinations.
For extremely short vehicles with a primary intended use as a hardcore trail machine, such as my '53 Willys flatfender, I run a spool in the rear and a Detroit Locker in the front. The spool mitigates any feedback through the chassis to the steering wheel that a rear automatic locker could impart, and the Detroit in the front is dirt simple and you never forget to turn it on like I frequently do with selectable lockers. I've found with my manual-transmission flattie I can modulate the throttle to get the Detroit Locker to freewheel enough to allow relatively tight turning on the trail. I ran the same combination (rear spool/front Detroit Locker) in my Ramcharger and never had any issues.
In a long-wheelbase vehicle that sees only moderately hardcore trail work, like my '68 M-715, I'll gladly run a Detroit Locker in the rear, and I'll usually leave the front diff open, or I'll run a tight limited slip like an Eaton Truetrac (my all-time, hands-down favorite limited slip). The Detroit allows much tighter turning when coasting (i.e. not under power) compared with a spooled rear and gives insane traction off-road. When doing almost any moderate off-roading that doesn't beat your sheetmetal to a pulp, a rear locker is frequently all you need.
For hardcore off-road trial rigs with longer wheelbases like my UACJ6D, I prefer selectable lockers front and rear. I've run ARBs on several rigs, and while I appreciate how quickly they engage and disengage, I've found Eaton ELockers to come close to matching ARB, but with a much less complicated installation. I've run ELockers in many of my trail rigs and have personally never had a failure, but we did have an engagement magnet go bad on UA2018 in the Derange Rover, so as is the case with most things, nothing is infallible. But overall, I would say an ELocker is my all-time favorite traction device.
I've spent more of my off-road years wheeling with open differentials in the front and back. Unless lines were intricately picked, and throttle was doled out with tender precision, my 2002 five-speed TJ Wrangler had a fun habit of spinning the tires in its opposite corners, leaving the ones with the most traction motionless. Yes, this is the plight of open, unlocked, un-welded, maximized-slip differentials—and they're my favorite, especially in the Dana 30/35 combination. Open diffs in this pairing make any slime pit or obstructing boulder a test of off-road skill. Balance that momentum with intricate line choice, use that left footed brake for your "traction-adding device," and don't get too exuberant or things can go "snap!"