When NOT to use your rear locker

Might not be a bad idea to discuss when using your rear locker is a bad idea…

Thinking back to my most recent adventure getting stuck, it does occur to me that perhaps part of my traction issues were due to having my rear locked. Basically, the rear would step out on me, and put the tires into ruts that I couldn’t climb out of.

Once I decided to try unlocking, it was of course too late (figures) as I had apparently used up the maximum number of times that reverse was a viable option. A-Trac was useless at that point unfortunately as I somehow was nicely wedged in.

In retrospect, I would have probably been better unlocked and using A-trac to keep better control of the situation before things went all pear shaped.

 

In my Tacoma, I have found that the rear locker would kick the rear end out on rutted out hill climbs while ATRAC wouldn't while providing enough traction to climb. It's one of those situations where you have to figure out what works and the one time I wished I had a front locker.

 

a big misconception about lockers is that it's an automatic get out of jail free card.

there are endless scenarios when it comes to traction out in the wild and managing it is part of the game when you're not on pavement. you win some and you lose some.

 

What do you all mean by the locked causing the rear end to “kick out” or “step out” ? Do you mean that with the locker on both rear tires would get pulled into the rutt(s) you were trying to get out of? Thanks for any insight or description, I’m just having a hard time envisioning what you guys are saying.

 

Instead of spinning a wheel, power gets shifted to the wheel with most traction.

That can have the effect of causing a fishtail situation, because suddenly you are sending a ton of power to one tire, which then breaks free as well and now you have two spinning tires on a slippery surface.

 

With an open diff, you get equal thrust from both wheels. The bad side is that if one has zero, the other one will have zero.

With a locked diff, you get equal rotations, but if one wheel has better grip than the other, you will have unequal thrust. The off-center thrust can put you into a spin or kick out on an icy surface.

 

I used to wheel with some folks that had auto lockers on their Wrangler. Apparently made for interesting travel in winter on ice and snow.

 

It was the 90s. Things were less dangerous then than they are now.

 

Sometimes when you’re stuck it’s too late to use your locker.

Time for plan “B”. Let out some air, stack rocks, get out the shovel, etc.

 

Had a Detroit locker in my 86 4x4. Talk about wild stuff on and off pavement. Muddy ruts were the worst. But that thing could climb anything.

 

Don't use in slippery off-camber situations (because of the sliding/ kickout mentioned), don't use on icy roads.

For snow and sand I think it depends on the situation. Sometimes it would be okay for one tire to spin, but if both spin they'll bury the back end or something.

Ideal locker scenario is when one tire has good traction but the other tire is spinning (possibly because it's unweighted), like crossing ruts or moguls or something.

I personally wouldn't use it on any loose surface if I can help it, or any time a little momentum is needed. For me it's more of a crawl out tool. (I am also afraid of breaking something while spinning the wheels with the rear locked).

 

Donuts in the mud = locked

 

For those that never use the rear locker, I would recommend engaging it every once in a while or you might have trouble getting it locked when you need it.

 

Can't say I've ever needed 4-lo on an actual road so not using the locker on icy roads is pretty easy.

Unless there's a mod that allows use of the locker in 4-hi that I don't know about yet (actually, come to think of it, I think I did see something that tricked the computer into thinking it was in 4-lo and threw all kinds of dash lights when activated).

the locker works great on slimy boat ramps though...

and I agree with the post above, use the locker every so often, maybe monthly when you put it in 4-lo...

 

I don't think it should be engaged unless one is already stuck (edit: "hung up"), or already certain that they'll need it.

There is one rock garden with a lot of loose rocks where I have left it engaged. Otherwise, I have generally only used mine after I couldn't get through an obstacle without it. I will also disengage it as soon as I get clear of whatever I was stuck on.

 

Ironically, I’ve seen some people say that you should have your locker on before you get stuck.

Which sort of seems like you need psychic powers.

 

Haha!

I've heard this, too.

I'd put that in the "already certain you'll need it" scenario. I'd put it on preemptively if an obstacle looks like it's definitely going to require it, or I've needed it in a spot previously.

 

I’ll say this much, A-TRAC is pretty impressive.

There were a few times last weekend when my spotter was ready to have me back up and try another line, and then…

“A-TRAC kicked in, yo!”

The looks of surprise never got old.

 

I've been relying on it heavily since my locker shit the bed. It's really fantastic once you get used to it!

 

As much as I feel like full lockers would be more effective, A-TRAC has a higher level of safety in that the programming is going to be conservative enough to avoid the breakage that a full mechanical linkage won't.

After all, power/energy has to go somewhere, and if the path of least resistance isn't moving the vehicle upwards or spinning tires, then a ticket to pretzel-ville or snap-city can be issued.

Reminds me of the time my clutch pedal linkage failed on an old CJ-5 with a limited slip rear. The tires had such great traction on the pavement that the driveshaft pretzeled and the spring-perch welds snapped.

Those AMC 304 V8s had some nice grunt to them.

 

It’s called reading the trail. Im one of those people who says you should engage the locker before you get stuck. The main advantage of the locker over the ABS-based traction control is that it can be used proactively, to avoid a loss of momentum. The ABS solutions require a loss of momentum before they’ll engage. You’re right when you say A-TRAC is safer, and it’s a great help to inexperienced drivers.

 

I suppose that would also fall under the "already certain that you'll need it" category.

I probably should clarify that I didn't really mean "stuck," as much as "hung up."

I have really only used mine in rocks. I prefer to keep it unlocked as it's just easier on everything when you're turning back and forth to follow the line you chose. You're generally not moving fast enough to be relying on momentum, anyway. And, if you get hung up, you can engage the locker just long enough to get past whatever you're stuck on, and then disengage it.

 

^This! If possible you want to avoid wheel spin altogether in most situations. When your tires spin they dig a hole/loosen up the surface, making things worse.

This was nicely illustrated by a recent magazine article I was reading wherein they compared an F150 "Tremor", a Chevy "Trail Boss", a Ram "Rebel", and a Toyota Tundra TRD Pro. One of the situations they put the trucks through entailed going up a steep and slippery hill with some rock steps. The F150, with its rear locker on so both rear wheels had to turn the same speed, "effortlessly" climbed that hill, "making the climb look as easy as inching up a paved driveway". The Chevy used an automatic locker which requires one of the tires to spin before it engages. And once there was wheel spin, it was "easier to back down and just carry a bunch of speed" to get over the section. To me, "carrying a bunch of speed" over rough terrain is just asking for trouble.

Nothing complicated or difficult about using a locker. Just don't be stupid and trying engaging it when one of the wheels is already spinning - that difference in wheel speed is what breaks things. If you see a section of trail that might require a locker then lock it; when you're past that section unlock it. And DON'T use it on a snow-covered or icy highway!

I have 3 different vehicles with lockers...plus the side by side. Use them all the time. Never had a problem with one.

 

Slippery hill with rock steps is a classic example. Some momentum is good. Too much momentum will cause a problem. The added momentum will carry the vehicle past the slippery part, but when it hits the step the vehicle will bounce off the suspension. It won’t leave the ground, but it will get light on the tires, traction will be lost, along with the momentum, and now the truck is struggling not to slide backwards down the hill.

 

And sometimes it’s a bit of a gamble either way.

Maybe you get the traction you need, maybe it kicks you sideways. I feel like on a muddy hill, you’re probably better off without the locker, but it’s likely to be a coin toss situation.

 

I took a recovery class taught by Bill Burke and this very subject came up — driving on muddy off-camber trails. His advice was to use tire chains, specifically diamond patterned chains that provide lateral resistance, to prevent sliding sideways. FWIW.

 

The best traction device sits between your ears. It’s best to engage it before you hit the trail!

 

I have to admit mine loses its grip every once in a while.

 

Agreed, I think I need to replace the bushings. Should I go with polyurethane this time?

 

I was impressed with the vehicle that had chains in this video...



Actually, scratch that - everything impressed me in this. It's like Top Gear at its prime, but focused on off roading and everyone just seems...happy.