Tystevens

Traction control and lockers are two very different things. Traction control essentially cuts power until the wheels regain traction, but doesn't shift power to the wheel with traction. So, if your left rear wheel has traction and your right doesn't traction control won't necessarily make so your left wheel gets the power.

With a locker, full power goes to each wheel. So if either wheel can get traction, you'll probably move forward.

Lockers can make a huge difference. When I had my old Jeep w/ a locker in the rear axle and the ability to run 2wd low range, I'd often see how far I could go in 2wd. I could go a lot farther than I expected in many cases.

Ricktwuhk

Yeah, there's a lot of people uneducated on both the difference and what they are used for.

brulaz

Yes, and when your 4x2 gets stuck and you need to rock it back and forth to get out, you need to turn off traction control. Even with my Limited Slip differential ...

2talltechie

When the traction control computer (often incorporated into another control unit, such as the ABS module) detects one or more driven wheels spinning significantly faster than another, it invokes the ABS electronic control unit to apply brake friction to wheels spinning with lessened traction. Braking action on slipping wheel(s) will cause power transfer to wheel axle(s) with traction due to the mechanical action within the differential.
http://en.wikipedia.org/wiki/Traction_control_system

packplantpath

But the one wheel spin control part of the system does act like a limited slip. It uses the abs system to pulse the brakes on the spinning wheel to transfer power. Not perfect and hell on brake pads but quite useful for the occasional need.

packplantpath

Beat me to it by seconds

brulaz

Everybody is partly right. From the manual:

"Excessive wheel spin is controlled in two ways, which may work separately or in tandem: engine traction control and brake traction control. Engine traction control works to limit drive wheel spin by momentarily reducing engine power. Brake traction control works to limit single wheel spin by momentarily applying the brakes to the wheel that is slipping."

Tystevens

True -- this is an old trick that you can try in a pinch -- but still no where close to the benefits of a locker.

The open differential always spins the wheel that will spin the easiest. That is how they work. So some added resistance to the wheel that is spinning freely will cause some transfer to the non-spinning wheel, true. This works on a situation where one wheel might have only slightly less traction than the other -- the brief bump of power to the other side through the differential is often enough to get you at least moving again.

But how much and to what effect, particularly where you are in a situation where one wheel has no traction at all, and you need the other to push you along? Unless ABS stops the spinning wheel entirely, you won't get full power to the wheel with traction -- you will likely only get a little bit, because the ABS will still let the slipping wheel spin. To complicate matters further, the engine cuts power once wheel spin is detected. It is fun to try this out in a snowy parking lot -- I can floor my truck, it'll break loose, and then only rev to 1500 rpm or so until the wheels get traction.

So by tricking the differential, I'd still submit you really aren't getting much power to the wheel with traction. Especially if you're in a situation where you're trying to tow a trailer across rough ground.

Meanwhile, the locker will apply 100% (or 50%, I guess) power to each wheel without any reduction.

This is probably all immaterial if you get a 4 wd -- 4wd will get you anywhere you want to get towing a trailer w/o the locking differential.

brulaz

Old tractors used to have two brake pedals or levers, one for each rear wheel. When one wheel started spinning you just applied it's brake to transfer all the torque to the other wheel. And I imagine you would reduce the engine speed as well. Manual traction control ...

Tystevens

You can apply the brakes on an old 2wd truck w/ an open differential and get a little power to the other wheel, too. Not much, but sometimes enough to get you moving a bit.