Selectable lockers, what's the skinny?

[haminawag]

I'm not planning on doing anything anytime soon, but...if I were to add a selectable rear locker to my QT Wag (D44) what are some of the negative issues, hassles, etc. Why the high prices? What are some good alternatives. I'm essentially a newbie at the 4WD game, so go slowly, I'm learning.

[will e]

Why so expensive is a good question. The major brands (ARB/OX/Yukon/etc) make the selectables almost bullet proof. But a good detroit is also almost bullet proof and hundres of dollars cheaper. The selectables have more parts (compressors, cables, etc) which add to the cost.

For the rear axle you are not excluded from running an autolocker. The lunch box lockers work very well. The general concensus is you don't run an auto locker on the front axles of a full time transfer case. Some folks will sugget against a autolocker on the rear axle of a rig you do a lot of towing with.

I have and ARB in the back and a aussie (lunch box) up front. My transfer cases have been part time. My current transfercase allows me to select power to the front wheels in or out of low range. It's an elegant solution. I manually lock the front hubs when I get on the trail and stay in 2wd rear only most of the time. Even with the aussie lunchbox locker up front there is no difference in driving until I engauge the front drive shaft.

My upcomming setup will be selectable both front and rear. The front axle already has an ARB. I will probably go the same for the rear. Part of this is to be able to NOT have the traction adding devices and it will make some of the wheel'n more fun in less difficult situations.

[COLORADOCRAWLER]

IMHO, if you are going to run a locker, selectable lockers are a must if you do much road driving in the snow. Reason being that auto lockers tend to engage/disengage when accelerating/turning through intersections, pulling into traffic, etc. causing your rear end to slide around or push you straight through the turn. Auto-Lockers are also harder on tires and drive train components because of the continuous engagement/disengagement while driving on high traction paved surfaces.

The primary reason I prefer a selectable vs. auto-locker is that when I turn my lockers off, it's as though they are not there. Auto-lockers/spools (or any locker when engaged) work to push you straight forward, thus widening your turn radius. A bunch of trail obstacles out there require you to make fairly tight turns to stay on a good, passable line that keeps your rig out of harms way. It is really nice to turn the rear locker off with front on to make a tight turn then re-engage the rear when the turn is complete. I have a ARBs front and rear in my baby Jeep and rarely even turn the front on if that's any consolation. Another benefit to selectables like OX/ARB/Eaton is that you can turn one locker off in off-camber situations where all four wheels spinning at once would cause you to side-slip into a hole (or worse, off a rock face to your doom). I've used this technique a few times to keep from sliding into oblivion. By turning the front off, only one wheel will spin at a time creating a sort of anchor point. The back may try to slide out a little, but at least you are now facing more uphill and typically will have an easier time climbing up and out.

The short answer: Selectable lockers are expensive but worth every penny, any locker will add a ton of off road capability to any rig, but can also help you get into places that your rig may not be capable of safely escaping without some creative thinking and a winch...or 2 .

[ferox]

I am no authority so someone will correct me if I am wrong, but at least some of the selectables act as an LSD when full lock is not engaged. This makes them much more useful in snow, and much better suited to travelling in mixed conditions snow-mud-asphalt-snow-etc. It's been a while since I looked at the info because I cannot afford them yet, but I plan on installing selectable lockers in my rig when my project list and budget coincide at that juncture.

[will e]

The selectable lockers I am familiar with (ARB which I run and OX which I have looked into) do not operate as LSD when not engauged, the act as open diffs.

Coloradocrawler makes a good point. There are actually times NOT having a locker on an axle can be a good thing.

I also run a transfer case that allows me to only send power to the front or rear even in low. Options are always a good thing.

[haminawag]

Thanks for all the information, good stuff, lots to consider. I'm pretty certain I'm gonna keep the original QT (BW-1339) transfer case as it is since it's in good condition and operates as it should. The PO installed manual locking hubs on the front axle, but thankfully never drove it with them unlocked, or at least never drove it far enough to damage the TC, (after he did his brain salad surgery to the poor old Wagoneer it wouldn't drive and would barely run) which, from the TCs point of view was a good thing I guess. It's going to be used primarily as a mild trail/camping rig in the mountains of NM, so I won't be using the locker too much. That's why I was hoping for a less expensive alternative.
My nearest experience with the Detroit locker was in a little Chevy Vega with a blown 402 and a Ford 9 inch, belonged to a fella I used to race against, he was on his way to a 10 second run when the rear end unlocked, it turned the car sideways at the top end and into the guard rail, nothing left of the Vega, he wasn't hurt bad but any Ideas I'd had up to that point of trying out a Detroit locker vanished, I stuck with the spool.

I'm not familiar with the OX, I'll look into it. What are your suggestions on the front axle (D44) of a QT? Thanks again guys.

[jamesdart]

I'm running the Yukon zip locker, I love it. It's nice to be able to turn it on or off.

[haminawag]

I'm running the Yukon zip locker, I love it. It's nice to be able to turn it on or off.

Tell me about it, how difficult to install, warranty, price? tnx

[Southern Gorilla]

I have no direct experience with any of the selectable lockers. But I wanted to share the thought process I went through when deciding which way to go.

My first plan was the Ox locker. Mainly because I like mechanical linkages better than air or electrical. I don't have any scientific reason for that. Mechanical just seems more robust and reliable to me.

But then I started researching the Detroit TrueTrac LSD. It's a Torsen-style unit that sends power to the wheel with traction as long as the other wheel has at least some traction. So it is only an open diff when one wheel is in the air. The Landrover crowd has a simple fix for when a wheel gets airborne though, they hold the brakes. That locks the airborne wheel and sends power to the other. Landrover and Audi both use Torsen diffs. Audi uses one in the T-case as well. Certain years of the Toyota 4Runner have a lockable Torsen diff in the T-case. So there's your AWD/Fulltime mode on the street and a locked mode on the trail.

The TrueTrac is an all-gear unit. There's no clutch plates or cones to wear out, no special fluid needed. And it is somewhat cheaper than the selectables. I suspect it would perform the same as an open diff as far as turning radius, but don't quote me on that. Anyhow, it's another option to look at. I'm going that route because my rig is going to be my DD. An LSD is more useful on the street than a selectable locker. And I don't plan to hit any technical trails where I might need a tire to freewheel to keep me from plummeting to my doom.

[will e]

For what you describe as your intended purpose a lunch box locker in the rear would be a good choice. They are less than $300 and you can install them yourself without having to reset the gears.

If you decide you like a locker you can then spend the money and upgrade to any of the ones mentioned.

If you are keeping the QT your best option for the front is a selectable locker. A few people will tell you they run automatic lockers on the front of a full time transfer case and it drives fine. I have an automatic on the front of my part time case and I can tell you that in the dirt there is a noticable difference in how it steers with the front drive line engauged.

[haminawag]

For what you describe as your intended purpose a lunch box locker in the rear would be a good choice. They are less than $300 and you can install them yourself without having to reset the gears.

If you decide you like a locker you can then spend the money and upgrade to any of the ones mentioned.

If you are keeping the QT your best option for the front is a selectable locker. A few people will tell you they run automatic lockers on the front of a full time transfer case and it drives fine. I have an automatic on the front of my part time case and I can tell you that in the dirt there is a noticable difference in how it steers with the front drive line engauged.

Yeah, that front auto-locker discussion on another thread was very interesting, but upon thinking it through I will not be adding one to my front axle. Maybe a selectable...someday, then again maybe not. I haven't done much study (or any) on the Dana 44 axle, cant the thing be set up tight? I used to run the Chrysler Sure-Grip diff. in one of my cars, I set it up TIGHT. That car left straight and stayed straight all the way through the quarter, it required very little maintennance, never acted squirrley when turning. But I guess setting up a front diff. too tight will benefit in off-road traction, but eat the tires on-road. huh? Just trying to find the happy-medium, best to get the plan laid out before turning the wrenches. I've got a ways to go before I'm there, still gotta replace the rocker panels.

[will e]

I think a limited slip in the front would be unpredictable.

[ferox]

...at least some of the selectables act as an LSD when full lock is not engaged.

It looks like Auburn used to make a selectable that functioned as an LSD when not engaged, but they had problems with them so they stopped production.

[haminawag]

So what do you guys do, run an open diff. in front with a select. locker? Or no locker? See, I thought the stock QT D44 WAS a limited slip diff., call me corn-fused.

[will e]

I ran a part time transfer case so front auto locker was fine. On the trail I locked the hubs and put it in low and it drove 'fine'. You knew it was there but I didn't find it to adversly effect driving too much. If I was going a little faster and turning on a dirt road you could kind of feel it slip/dig.
With the Atlas in I can run in low transfer case gears and rear wheel drive only. So I lock the front hubs and just engauge/disengauge the front drive. When I am in 2wd rear, even with the hubs locked, it drives as if there was no locker at all.

[jamesdart]

before I confuse you anymore, I swapped out my 400 and qt, at the same time I regeared and added the zip locker. i planned on gears and lockers with the qt case, but my chain went first so, im now running a part time case. I still run the stock open front diff. the zip locker is an air locker, similar to the arb. when disengaged, its an open diff. when locked, its like a full spool, unless something breaks, there is no give. from what I remember when shopping around, Yukon has a better warranty than arb, and supposedly way better customer service. if you do your homework, you can find the yukon zip for quite a bit less than the arb. I regeared at the same time so I cant really say how difficult it would be to just add the air locker. should be pretty easy. unlike the factory setup, the zip locker uses shims outside of the carrier bearings so to adjust the backlash and carrier preload, you don't have to keep pulling the bearings. that's much easier for a diy guy. I was torn between installing it in the front or rear. i guess each has its own advantages. there have been times i wished i had front and rear, but i have never wished i installed it in the front instead of the rear.it does need some kind of air supply to power it, but oba can be a nice thing to have.
my friend has automatic lockers front and rear and he kept blowing apart hubs on his front dana 60. he was running the external style selectro hubs. we been told the external hubs are weaker, and there arent many options for them. now he runs drive slugs, puts them in at the trail. its cool when playing on the rocks or hills, but as short as a ramcharger is, you can feel it not wanting to turn on tight trails. i could have done the same as him, and bought 2 auto lockers for what i spent on one, but i don't regret it, it works good.

[haminawag]

I appreciate all the info. from everyone. I'm just getting into the reading stage, I plan to be there a while. Here's what I've determined so far: Auto-lockers are out, not gonna use 'em front or rear. OBA is a great thing to have, no question about that, but for my purposes I think it's beyond the scope of my particular needs, so no air-lockers either. I studied up on the Torsen style diffs. turns out I've worked on them before, years ago, lots of moving parts, but further study will be needed. I need to study up on the Ox locker, cable actuated...hmmm...stay tuned, don't touch that dial.

[will e]

I don't know that I would rule out air lockers completly. The ARB has a very small compressor, it doesn't take up much room at all.

[REDONE]

I don't know that I would rule out air lockers completly. The ARB has a very small compressor, it doesn't take up much room at all.

Of all the selectables, it has the stongest following too. Being the first selectable locker, it wouldn't gain a reputation like that and be able to KEEP it if it weren't worth it.

Ferox, I'm pretty sure the Eaton E-locker is a limited-slip selectable locker.

Haminawag, no doubt selectable lockers are the bee's knees, but they are a hefty chuck of coin for what they do. With your racing experience and admitted novice-ness into the off road world I think you should strongly consider the Power Lock limited slip differential for the rear axle first.

http://www.ringpinion.com/b2c/ProductDe ... r_and_Axle

This limited slip is probably already known to you because it's famous in the 1/4 mile world. It can be set up "loose" or "tight" and is regarded as pretty much indestructable until it get's worn, and the most common failure is AFTER it's worn out, it will smoke the clutches and chatter. Even then, it's fully rebuildable.

Unlike the True Trac, which is not at all "Torque sensing" (I'll explain in a minute), the Power Lock is truly Torque sensing. If you open the link above and look at the opening in the case, with one side round and the other a "V", that nub in the center is one of the 4 cross pins (stock D44 has one cross pin that engages the case at two points, the Power Lock has a "+" with four ends, so not really four cross pins, but you know what I mean). A spring pushes the cross pins and spider gears AWAY from the clutch pack inside, which sets the cross pins in the crotch of the "V". As differential torque is applied, the cross pins ride up the wall of the "V" against the springs and apply pressure to the clutch pack, biasing the torque. After you play with it, trying different set ups and what not and decide to lock the rear, you can move it to the front, so it's not a throw away investment either.

Now the True Trac and all the diffs like it are NOT torque sensing, they are "Differential Wheel Speed" sensing. I'll post a pic so anyone following along can see, but most people see those sideways worm gears and figure an engineer hit it with a slide rule and it's full of magic that makes it sense torque.
http://www.summitracing.com/parts/dtl-9 ... 7AodrXwAeQ

Truth is, those are oil pumps. Helical gear oil pumps, so now do a brain exercise; Imagine you cranking a hand-crank oil pump, but over the discharge port is a pipe cap. Obviously, once you build up pressure, you can't turn it anymore because the outlet is capped. Now drill a very tiny hole in the pipe cap. Now the hand crank turns and oil squirts out the hole, but the faster you turn the hand crank, the harder it gets. That's how the True Trac works. The more differential wheel speed there is, the more oil it tries to pump and the more resistance there is to that differential speed. I often get myself in trouble for calling the True Trac the "ladies limited slip", but it's got tons of manly applicability, but they are all at speed, which is why they are so popular in rally racing and found in high speed performance cars. Now if you think about your mom, your sister, or your girlfriend/wife and picture them doing a three point turn on a dirt road and backing a tire into the ditch, what's the first thing they do when a tire starts to spin? If they're anything like the ladies I know and love, they floor it while gritting their teeth. Same thing with an iced over driveway, or after sliding into a snow bank, or accidentally driving into a mud bog. This is where a True Trac shines and why I call it a ladies limited slip.

[haminawag]

Thanks for the ideas everyone. Redone, I'm glad you responded, I was trying to imagine any off-road scenario where a "Sure-Grip" type of diff. in the rear wouldn't work, and I can't. It was an awesome diff. to use, never gave me a lick of trouble despite getting pounded by an 800 horse Mopar BB for months on end. But it was set up tight, not the best idea for a street driven truck where fuel mileage will be of some concern, the trick would be in getting it set up for the varying conditions of an off-road environment, for that I keep going back to the selectable locker in an open diff., but I'm not made of money. I'll study what you've posted for me. Man, racing diffs. are a cake-walk compared to this SJ stuff you guys got me into. I used to have just three diffs., a sure-grip, and two Chrysler 8-3/4 units, one for A-bodys the other for Bs, both had spools in 'em. Ya know you're sick when the cars come and go but the drive trains stay in your garage. hah!