Manual (aka Selectable) Lockers
Selectable lockers are designed to give you the best of both worlds. When the locker is set to open, most act like a standard open differential, though some work similar to a limited slip. When engaged the units lock 100 percent and allow zero differentiation in axle speed between the shafts.
Unlike automatic lockers, selectable lockers require an activation source. For the ARB Air Locker (www.arbusa.com) and the Yukon Zip Locker (www.yukongear.com), an air line and small compressor are required, while the OX Locker (www.ox-usa.com) uses a cable and Auburn Gear’s Ected (www.auburngear.com) is electronically actuated.
• Great for daily drivers
• Excellent on-road characteristics
• Can increase maneuverability on- and off-road
• Higher initial cost
• More external and moving parts to contend with compared to an automatic locker
• When engaged the lockers function as spools, which can make steering difficult.
Welded Spider Gears (aka Lincoln/Miller/Hobart Lockers)
For years they’ve been referred to as Lincoln Lockers, but not because the welding corporation produces an off-road line of traction aids. Lincoln Locker is just slang for welded spider gears functioning as a spool. Welding an open differential’s spider gears together or to the case unifies the gears to make the axleshafts rotate at the same speed. This is great for off-road-only rigs, as you can have your rig locked up in less than an hour using only a drain pan, a can of brake clean, and a welder.
• Extremely cheap
• Not good for driving on the street
• Welding risks differential damage
• Spider gears can be difficult to weld
• Weaker than full replacement carrier
• Not recommended for front end
Spools have a great history in drag racing and have become a staple in the off-road world, especially in mud racing. These lightweight fulltime lockers are extremely aggressive when used on the street, as they allow no difference in speed between the shafts. Spools are complete carrier replacement lockers and can range in material types.
Another type of spool is the drop-in style mini spool (Randy’s Ring & Pinion, www.ringpinion.com). The mini-spool is an equally aggressive traction aid that simply takes the place of your open differential’s spider gears.
• Very aggressive
• Not meant for highway use
• Not C-clip compatible
• Not recommended for front end
Brake Bias Traction Control
Many modern 4x4 vehicles have what’s known as brake-bias traction control. These systems work by manipulating the vehicle’s antilock brake system (ABS) to lock up each wheel individually when it senses that one tire is spinning much faster than the others. The idea is that by applying brake pressure to the wheel that is spinning freely, the differential will engage the other wheel(s) and will hopefully grab and move you forward. Though we’re not huge fans of this type of traction control, some implementations of it are getting better, like Toyota’s A-Trac system.
An open differential is a differential carrier fitted with a set of spider gears that allows for different axleshaft speeds. When throttle is applied, the open differential sends power to the wheel with the least resistance, which usually is the tire with the least traction. This design is sufficient on-road because it allows the tires to spin at different speeds, so when you corner and turn the vehicle there is no bind. Off-road, open diffs can usually be compensated for by driving finesse and momentum, but they ultimately limit the potential of your 4x4.
• Great for street driving
• Cheap, as most vehicles are already equipped with them
• Usually leaves one wheel per axle doing all the work
• No mechanism to lock shafts together