What's an Open Jeep Differential?
Open differentials come stock on most Wranglers, and they are gearboxes designed to allow one wheel to rotate faster or slower than the other when turning. This helps prevent your wheels from hopping around turns, wearing out your tires faster, and causing you to lose traction. How this works is when you are driving normally and you take a turn, your outside wheels will want to turn faster because it has to travel farther than your inside tires.
This system works best when both wheels have an even amount of traction which is easy on pavement. However, when you are off-road it is easy for one wheel to have more traction than the other causing one to spin and the other to act like a limp noodle.
Limited Slip Jeep Wrangler Differentials - Not Open, Not Locked
Jeep limited slip differentials combine the benefits of an open and a locked differential. They are less common on Wranglers than open differentials. A limited slip differential was a factory option and is also sold as an aftermarket upgrade. It is designed to act like an open differential in most driving conditions.
In conditions where both wheels have an equal amount of traction and the vehicle is not turning, the differential will spin both wheels at the same speed with an equal amount of torque. This is how vehicles with limited slip differentials are able to do burnouts.
In conditions with poor traction like on snow, ice, or mud, where one wheel has less traction than another, the differential will send more torque to the wheel with more traction. Limited slip differentials are better than open differentials at providing extra traction to the wheels, however, lockers provide the most traction on uneven surfaces like mud and rocks. This is because they provide the benefits of both an open differential and a spool/locker.
Limited Slip Differential Cut to Show Internals
What is a Jeep Locker or Spool?
A Jeep Wrangler locker or locking differential, is designed to “lock” both wheels of the same axle together so they both move at the same speed with the same amount of force. Without a locker it would be difficult to do any rock crawling due to there would almost never be an even amount of traction. This is thanks to rocks being different shapes, sizes, textures, and some may have dirt covering parts of them making for a very slippery surface.
There are two ways to convert to a spool/locker type differential. There’s the full spool which replaces the entire ring gear carrier, and a mini spool which fits inside of the existing ring gear carrier replacing the spider gear assembly. Both forms have the same effect. A locker should not be used in vehicles that are intended for anything other than drag racing or extreme off-roading. However, there are two main kinds of lockers for Jeeps (automatic and selectable) which have their own pros and cons (and can beat back the off-road only tag).
Locker Differential Cut to Show Internals
Pros and Cons to Automatic Lockers
- Always ready when you need it
- Quicker and easier installation
- On-road handling is impacted
- Resistance on sharp turns
- Possible tire skip when cornering
- Makes a clicking sound
- Can impact handling in snow
- Always engaged until you let your foot off the throttle
Pros and Cons to Selectable Lockers
- When disengaged it acts as a normal open differential
- Precise control over when it is activated
- Doesn’t effect on-road handling when disengaged
- Can cause serious damage to differential if you forget to disable it
- More complicated installation
- More components to fail
- Has to be manually activated
What are Jeep Lockers Used For?
Jeep lockers are most useful in situations like rock crawling, self-recovery, and the recovery of others. In rock crawling, you are likely to have a lot of changes in traction between different rocks and angles, so it is possible the wrong wheel could start spinning. Another possible situation in rock crawling is if your Wrangler doesn’t have enough articulation causing a wheel to lift off the ground. Lockers are designed to give you more traction when you need it, whether you are off-road or just pulling a friend out of a ditch.
Do Jeeps Have Locking Differentials Stock?
Unless you have a Rubicon, odds are you have an open differential. Although, JKs will have a brake lock differential if they didn't come with lockers. BLDs are a substitute for lockers with their own benefits and disadvantages. BLDs rely on the braking system to simulate how a locker works. Submodels such as the Sahara and the Sport S had the option of a limited slip differential from the factory.
So how do you tell which differential you do have? The easiest way is to jack up the front or back so both tires are off the ground. Rotate one tire. If the opposite tire spins the opposite way or not at all, you have an open differential. If the tire spins in the same direction you have an LSD or a locker.
Fitment includes: JL, JK, TJ, YJ, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, Laredo, Sport, Islander, S, Sahara, Renegade, SE, X, Rubicon, Unlimited, Sport-S