Lockers are devices that keep your wheels spinning even if you are losing traction. In most vehicles, when one tire begins to spin (lose traction), all of the power goes to making that tire spin to regain traction. A locker sends an equal distribution of power to both wheels on an axle.
A locking differential provides equal torque to the vehicle’s wheels by forcing both wheels to turn at the same speed. A selectable locker can be turned on or off with a switch and allows open differential driving while on the road, and a locked differential when off-roading.
“Why,” might you ask, “do I need a locker?” When your vehicle is climbing an obstacle, it might have a boulder on the right side but not on the left side. As your right tire begins to climb the boulder it lifts your left tire up in the air resulting in a loss of traction for that tire.
If you are not equipped with a locker then as your left tire loses traction, all of the power is sent to your left wheel to try and regain traction. Meanwhile, your right tire is left stuck, with not enough power to get you over that boulder. A locker would automatically distrubute that power equally so that during the few seconds your left tire is in the air, you will feel no difference in power, it will be constant and steady. The best way to get over an obstacle is to crawl, and a locker can help you to achieve this.
A locker can be added to the front or rear axle of your vehicle. If you want to add each locker seperately, the best is to begin with the installatin of a rear locker. The rear locker will do more to help you off road than just a front locker. Most of the time when you need a locker to help you get out of an obstacle, your vehicle is going uphill so most of the weight shifts to the rear. A rear locker makes a big difference in everyday four wheeling, while a front locker can help you through a massive boulder field or other rough/rocky terrain.

February 11th, 2010 at 8:17 pm
I have an 09 Jeep Sahara that I plan to have lifted [2.5 in.] with 35 in. tires. My dealer Airpark Dodge, Chrsler & Jeep in Scottsdale AZ, uses the Teraflex lift and will still guarantee my warranty. Since the Sahara comes with a 4 wd positraction rear end, would I better off to put front lockers on first or would you still recommend a rear locker to begin with. I’m new to 4 wheeling and retired. So I need to upgrade my vehicle in stages as finances allow.
February 15th, 2010 at 12:53 pm
Ron,
Eventually you’re going to want to do both for sure. Since you have a limited slip differential on the rear already you’d be just fine starting with a front locker. Any type of drop-in locker will be your least-expensive option for the front end. Good luck and welcome to the off-roading community!
Kyle