Lunch box lockers work marginally well in a light rig

An axleshaft is like a torsion bar or spring. It will twist to a degree when torque is applied.

In a light weight rig where torque is not very forceful since the tires can slip (chirp) a little where traction is good.
A lunchbox style locker is a pretty crude design that does not sense torque biasing very well. They do not engage/disengage very smoothly at all. So when a rig is heavy or has a heavy load and is cornering with decent traction, the lunchbox does not unlock/react smooth or properly. During this time of cornering, the axle shafts are starting to twist and absorb the differential between the two different radius/circles/paths that the outer and inner wheel are traveling. Now that these axles have absorbed a good amount of twist/energy, then the lunchbox finally unlocks (late) and lets go of all this stored energy.

So a "pop"or "clunk" is not a big deal on a light weight rig. BUT a pop and a clunk with 10,000lbs on the ground and a good amount of torque applied can end badly and turn into a CRACK and a BOOM and then the rig stops moving under its own power and things get expensive QUICK.

And a welded diff?? C'mon, were not drunk teenagers in beat up jeep cherokees.

I have setup/built hundreds of diffs and lockers and gears. I have plenty of broken lunchbox lockers in my pile. I used to save the junk ones (since they always dies on ONE side) and eventually another would come in and I would assemble another one from the two remaining good halves.

There is only 4 parts in a lunchbox locker.

Compare that to the MANY parts in a DETROIT/NoSpin locker and ask yourself, why would Eaton design the Detroit/NoSpin with so many parts when they could have got the same results with just 4 parts instead.

So I walked out and unlocked (no pun intended) the shop and snapped a couple
Pics.
In the first pic will see the 4 parts of the lunchbox locker. This one happens to be Detroit EZlocker, one of many mfgers that all make identical products. Notice the four parts that make up the badly designed lunchbox. The outer and inner gear for the right and another pair for the left.

Then you will notice the second pic is of a side with worn but not broken ratchet teeth.

Now the third pic is of a lunchbox side with chips on the edges of the teeth and rounded corners. This is JUNK. This is the eventual fate of ALL lunchbox lockers. Especially in a rear axle application where they see many miles of driving on high traction surfaces like paved roads.
Lastly just a pic of one of the dozens of bins of diff junk out here, lol

A factory posi out of an early 2000s explorer will fit, they all had 8.8s with 31 splines, most had Posi's. I have one sitting here with 3.73s, disc brakes and a posi I paid 75 bucks for. i have installed a dozen or so over the years, all had good clutches. New clutches would not be a bad idea though. Just an option. Detroit tru trak is a great posi with no clunk if money isn't a big deal.

Front end never gets used... It's 2wd. Sorry, I should have mentioned that


The elocker is what I was leaning towards. Air would kinda be nice but there isn't much else I would need it for. I can air up tires at the shop

99% of the time I'm driving on paved roads with little weight in the back. It's only 1% of the time when I'm pulling the trailer up the hill at the dump or on some backwoods dirt road going to a cave or climbing area where the chance of getting stuck are increased that I want the locker. The rest of the time I don't want to know it's there


Why else would I come here!

I end up using the on board air on my tacoma way more often than you would expect.

It's easier to drive the taco over to something that needs sir than it is to drag an air compressor.

Interesting, I didn’t know they could be so problematic in heavier vehicles. Thanks for the education.

That can of Rainier gave me flashbacks

Lunch box and the like will be noisy as heck too.

I have air lockers front and rear. They work GREAT.

The main weakness with an air locker is the cost and need for super competent installer and an air pump. I guess those are three weaknesses.

Are there e-locker options for that differential?

The used posi sounds like the lowest cost easiest option - but not a true locker.

That what I was worried about, plus the drivability


Every time the truck needs new tires it's totalled. So cost is like sex in Kentucky, all relative. I'm doing all the work myself so I guess there's 'savings' in that, plus I'll know it's done right


Yes, Eaton makes a couple Detroit lockers, a posi, and an elocker. The Ferd 8.8 was pretty common, the same lockers fit 1987-2014 diffs with 31 splines. ARB makes air lockers, they're not much cheaper plus I'd have to add a pump and tank. Not that I'm opposed to that but it seems like a bunch of extra stuff that won't have to many other benefits


That's tempting but I think I need a true locker. If I'm going to go to the trouble of doing it I want to be sure it's going to work

Im not going to poo poo on your mechanical abilities, but an air locker is something that many PROs still dont do correctly.

I have corrected MANY of them over the years. Bearing preload and many other things are very crucial for it to operate correctly.

I 100% recommend a posi for your application.

Much of a difference between an air locker and an elocker?

I appreciate the input, all of it. I figure with 350k on the clock I should probably replace everything in there while I'm at it. I'm not daunted by the process of rebuilding a diff. I'm also not surprised you've had to repair what pros have done. I've had to do the same and have given up on relying on other people to do work on my stuff

Elockers are generally frowned upon by the 4wheeleres since some have tender exposed components like actuators and elaborate diff covers with bulky mechanicals.

The air locker is a picky critter. Air is transferred thru the axle housing with an airline/hose that transitions to copper tubing that then goes into a ring that is basically a thick carrier shim that transfers the air to the rotating carrier that has a spot to receive the air.

The placement of the ring is crucial for a useful and leak free junction. Then carrier bearing preload is VERY important because any movement in the carrier will cause air leaks (as well as longevity issues with the diff itself).

Many installers focus on gear pattern and not enough on bearing preload and deflection caused by applied torque and the way it influences the pattern/setup during the application of torque/traction.

You can build diffs for 40years and you will continue to learn/get better as long as your a good mechanic.

Every time I think Ive seen it all, a new can of worms gets to my bench and VOILA! I get to expand my education!

In your situation, Id lean toward the E-locker option.

But hey, there is nothing like spending $1100-1300 just in parts when a $300 POSI will work great without all the related BS, lol

I take it you have not seen or used a Powertrax No-Slip locker then. It is a lunchbox locker, and it has way more than 4 parts, and does not behave like the other basic Lock-Rite etc lunchbox lockers. It uses a synchro mechanism to minimize that behavior, as I said in my previous post.
Note the inner synchro rings in the pic Jegs shows:
https://www.jegs.com/i/Powertrax/754/9206883107/10002/-1

Also, at least one of the newer e-lockers is all internal and does not need a special diff cover or have any exposed parts.

A posi setup can be great for the street. Sometimes it's not enough when that same vehicle gets offroad though, especially when the other differential is just open. It's up to the OP to decide how that fits his intended use.