All About Lockers

[peteyg]

I wrote this because I see a lot of info posted about lockers. Sometimes it's not right, sometimes it's incomplete, and sometimes it's very biased. I tried to put together a list of commonly available lockers and how they work. I know I missed some stuff and probably got something wrong. It would be GREAT if this could be made a sticky. I know this stuff has all been covered before, but it always gets buried, and it's the second most popular question behind "What gears should I use?" Additions/Corrections are welcomed. So here goes:

Lockers as I know them:

There are several types of lockers and limited slips out there. In my mind, there are three types of hard lockers, and several limited slips. First, I'll differentiate between lockers and LSDs.

An OPEN differential is one where ALL of the torque is sent to the wheel with the LEAST amount of traction. This is why one wheel will spin while the other doesn't.

A LIMITED SLIP differential allows SOME of the torque to be sent to the wheel with the MOST amount of traction. Better than open, but it WILL still slip when the traction requirement goes beyond the capability of the LSD to hold.

A LOCKER locks the axles together, sending equal power to both wheels, ensuring that the wheel with the most traction turns. A true locker allows some limited differentiation between the wheels. A wheel can spin faster than the ring gear, but not slower. (Parts of this definition were contributed by Weldmn)

Now, lets take a look at the different types of limited slips there are:

Trac-Loc - This is a very popular OEM type Limited slip that uses clutch packs behind the side gears to lock the axle together while allowing the wheels to spin at different speeds. Trac-Loc clutch packs look very much like automatic transmission clutch packs, but smaller. Ford uses Trac-Loc as the OEM limited slip if you purchased your vehicle with a limited slip.

Auburn Limited Slip - I don't know a lot about Auburn limted slips, but I believe they use a set of clutches and springs to provide the tension on the side gears.

Posi-Traction - I have no idea of the internals of a Posi unit, since I've never worked on one, but it's a limited slip like the others.

(Contributed by BlueBronco)
PowerLok is another clutch type limited slip by Dana that is pretty good but pricey for what it is.

(Contributed by Lonestar_Bronco)
Detroit Truetrac - a geared LSD with no clutches

Next up, lockers. Lockers fall into two distinct categories, with each category having it's own sub-categories. First we'll look at Automatic Lockers. There are two types of automatic lockers: Full Carrier Lockers and Lunchbox Lockers (those that are installed in the stock differential carrier).

Lunchbox Lockers:

PowerTrax Lock-Right - This is a very popular locker that is most commonly used in front axle applications. It is intended for light to medium duty wheeling, and will most likely fail when used in the rear of a heavy vehicle with large tires or a lot of horsepower.

PowerTrax No-Slip Traction System - PowerTrax does not call this a full locker, but it is. Basically, it is a modified Lock-Right with something they call a Synchronizing ring that eliminates the harsh engagement commonly found in the Lock-Right. I had one of these in a Full Size Jeep Cherokee, and it worked very well. I installed one in the rear Dana 44 in a Jeep and it broke as the guy pulled out of my parking lot. The syncronizer ring had a flaw and broke in half.

Detroit EZ-Locker - The EZ-Locker is basically the same as the Lock-Right. I have had both lockers, and visually there is very little difference between them. In use, the EZ-Locker seems to be smoother than the Lock-Right.

(Contributed by BlueBronco)

There are 2 other lunch box lockers . . . the Aussie and the QuickLok.

These all basically work the same way. A set of tooothed clutches replaces the spider gears and provides full and positive engagement of both axleshafts.

Full Carrier Automatic Lockers:

Detroit. This locker replaces the entire carrier assembly with a much stronger unit. The Detroit is the Gold Standard in lockers, and is suprememly strong. It was originally designed for military use. In fact, there is one exception to the carrier being replaced: 14-Bolt GM axles. The 14-Bolt carrier was designed to take the Detroit internals. That's why you pay so much less for a Detroit for a 14-Bolt. You don't need the carrier. Detroit lockers are ALWAYS there, and have quircky on-road driving charateristics. Off-road, Detroits are awsome.

GM offers the Gov-Loc, which is a GM OEM full carrier locker available in their Corporate axles. This unit normally operates as an LSD, but a counter-weighted locking mechanism locks the side gears together when the wheels have a speed differential of something like 100 - 200 RPM. It makes a very interesting "BANG" when it engages, and if you ever saw one you would be afraid to have it engage. They seem to work well, though, and GM has offered it for decades.

Selectable Lockers allow the axles to operate as open differentials until the vehicle operator engages the locker. There are at least 3 types of selectable lockers available: Air Operated lockers, Cable Operated lockers, and Eletrically operated Lockers.

Air Lockers:

The biggest player is ARB, and they are the Gold Standard of selectable lockers. ARB lockers require additional air system plumbing and compressors to operate, and they cannot be installed in a driveway by shade-tree mechanics. ARB installation is very complex, and unless you've done it before, it is a job best left to a shop.

The Jeep Rubicon uses a strange air locker from some company from Japan. It uses two little electric solenoid/compressor assemblies mounted to the frame rail. I have not seen these lockers sold independently.

Cable-Select Lockers:

The OX Locker is the first commercially marketed cable select locker, and has had mixed reviews. The biggest complaint is with the cables binding up and being unable to engage/disengage the locker.

Electric Lockers:

(This whole section contributed by BlueBronco)

Eaton makes the E-Locker and Auburn makes the Elected, and Detroit makes the Electrac. These electric selectables all work differently. The Electrac is like a True Trac limited slip when off and a detroit when on. The Eaton is like an open diff when off and is spooled when on. The Elected is like a ls when off and a locker (I think) when on. The Auburn is very complicated design wise. The Eaton doesn't have any external solenoids on the cover to whack but Detroit has resolved this on there newer designs as well.

Corrected by Weldmn
Toyota has had an electric locker available for it's axles for many years. You can buy this locker from TRD.

And then there are Spools.

A spool is a device that physically attaches the axleshafts to each other, permanently. There is no differentiation. There are a lot of different opinions on spools, but I will leave that debate to others.

There are three types of spools: Full spools, mini-spools, and Lincoln Lockers.

Full Spools replace the carrier and are very strong.

Mini-spools are like lunchbox lockers, in that they replace the spider gears, but use the stock carrier.

Lincoln Lockers - so-named because Lincoln is a famous brand of welder. A Lincoln Locker is nothing more than an open differential with the spider gears welded together. This is by far the cheapest method for locking a differential.

I will say this about spools:

You will wear your tires very quickly if you drive a spooled vehicle on the street for any period of time. You will chirp your tires whenever you make a turn, and it will drive very differently than a vehicle with a locker. That said, many people have spooled their rear axles and are happy with the results.

Some will say they have even spooled their front axles. They even sometimes claim that it behaves as if it wasn't there.

I have this to say about that:

DO NOT SPOOL THE FRONT AXLE. You will be unable to steer. Yes, you can take it out of 4WD to steer. You will get tired of this very quickly. You will be MUCH happier with a lunchbox locker in the front. There, I said it. I know this is a controversial subject, but I feel very strongly that front axles should not be spooled.

Again, please feel free to update/correct this list. I'm not trying to promote any one locker over another, but I constantly see people asking about them, and have never seen anyone put a definitive list together.

[Bronkzilla]

Welded.....?

[peteyg]

Originally Posted by Bronkzilla

Welded.....?

Yup Forgot about spools. I'll add a section on Spools in the morning.

[MyFullSize]

I had a LockRight in the rear (GM 10bolt) of an S-10 Blazer, 4.3L with 3.42 turning 30X10.5. I wheeled easy with it at first, skeered Id hurt it. Then graduated to mild and medium wheeling. Finally, hitting some hard trails at Uwharrie National Forrest (NC) with it. It refused to fail, not lock correctly, or meet my expectations.

After that, I started trying to hurt (read:damage) the locker. Id do stupid chit like hammer down on the gravel and pull onto the pavement, you *know* thats not good... I just got traction. I tried repeatedly to do harm to the locker. One wheel on pavement, one in the mud, and smack the skinny pedel to the floor. Nothing, still no thud or clunk. I towed with it, I pulled others out the ditch or mudhole with it. I blew a few front half shafts with the wheeling I did, but the LockRight refused to grenade.

So, Im close to selling the Blazer and getting the Bronco on the road, I remove the LockRight and CLOSELY visually inspect it. It appeared to be in the exact same condition as it was when I installed it! There were no signs or indications of damage or failure. I figured Id be able to hurt it, was a bit disappointed I did no more to it than I did, which was just drive with it.

I can tell you locker stories if you want, and Ive got some video on VHS that needs to be digitized if you want to see it in action, but for now Ill just leave the post as it is.

Now, on the flip side. Running a LockRight with LARGE tires, were talking 33" and larger, with gobs of power turning it, were talking 351W or simililar/better, I cant attest to how well it would hold up. However, I have seen in plenty of 4X4 rags "Reader's Rides" that were big and built, and running big tires (33" & 35") with V-8s, and there running a LockRight in the rear, or both front and rear. I figure that has to say something for them?

Anyway, thats what I know, from research, reading and experience.

HTH,
Andrew

[BlueBronco]

There are 2 other lunch box lockers . . . the Aussie and the QuickLok.

Also, PowerLok is another clutch type limited slip by Dana that is pretty good but pricey for what it is.

There are at least 2 other electric lockers. Eaton makes the E-Locker and Auburn makes the Elected. Detroits is actually called the Electrac. These electric selectables all work differently. The Electrac is like a True Trac limited slip when off and a detroit when on. The Eaton is like an open diff when off and is spooled when on. The Elected is like a ls when off and a locker (I think) when on. The Auburn is very complicated design wise. The Eaton doesn't have any external solenoids on the cover to whack but Detroit has resolved this on there newer designs as well.

My 4 cents on the subject. Good info PettyG!

[peteyg]

Originally Posted by MyFullSize

I had a LockRight in the rear (GM 10bolt) of an S-10 Blazer, 4.3L with 3.42 turning 30X10.5. I wheeled easy with it at first, skeered Id hurt it. Then graduated to mild and medium wheeling. Finally, hitting some hard trails at Uwharrie National Forrest (NC) with it. It refused to fail, not lock correctly, or meet my expectations.

After that, I started trying to hurt (read:damage) the locker. Id do stupid chit like hammer down on the gravel and pull onto the pavement, you *know* thats not good... I just got traction. I tried repeatedly to do harm to the locker. One wheel on pavement, one in the mud, and smack the skinny pedel to the floor. Nothing, still no thud or clunk. I towed with it, I pulled others out the ditch or mudhole with it. I blew a few front half shafts with the wheeling I did, but the LockRight refused to grenade.

So, Im close to selling the Blazer and getting the Bronco on the road, I remove the LockRight and CLOSELY visually inspect it. It appeared to be in the exact same condition as it was when I installed it! There were no signs or indications of damage or failure. I figured Id be able to hurt it, was a bit disappointed I did no more to it than I did, which was just drive with it.

I can tell you locker stories if you want, and Ive got some video on VHS that needs to be digitized if you want to see it in action, but for now Ill just leave the post as it is.

Now, on the flip side. Running a LockRight with LARGE tires, were talking 33" and larger, with gobs of power turning it, were talking 351W or simililar/better, I cant attest to how well it would hold up. However, I have seen in plenty of 4X4 rags "Reader's Rides" that were big and built, and running big tires (33" & 35") with V-8s, and there running a LockRight in the rear, or both front and rear. I figure that has to say something for them?

Anyway, thats what I know, from research, reading and experience.

HTH,
Andrew

Big tires is the key, and you're not doing hard wheeling on 31's. At least, not my kind of hard wheeling.

I've seen a Lock-Right literally explode through the cover of a Jeep axle on more than one occasion, and it is VERY common for them to wear out the drive side teeth. But again, these were with 33" to 35" tires, and running almost all of their life in rocks. Lock-Rights are intended for mild to moderate wheeling, with small tires. They are commonly pushed far beyond their limits, and are a good product for what they are. It's just important that people know that they were never designed to handle extreme duty wheeling, and they can and do fail on a regular basis when used beyond their limits.

[Pony-boy]

ARB lockers can be installed in the driveway if you are equip with the correct
tools and you follow directions carefully.

[5.0-BRONCO]

THIS IS GOOD THREAD, I WISH THIS WAS OUT WHEN I WAS A NOOB.

[Lonestar_Bronco]

You might add the Detroit Truetrac, as it is a geared LSD with no clutches.

[jopes]

Originally Posted by peteyg

Some will say they have even spooled their front axles. I have this to say about that:

DO NOT SPOOL THE FRONT AXLE. You will be unable to steer. Yes, you can take it out of 4WD to steer. You will get tired of this very quickly. You will be MUCH happier with a lunchbox locker in the front. There, I said it. I know this is a controversial subject, but I feel very strongly that front axles should not be spooled.[/indent]

I welded up my front diff in both my dana 44 and now my dana 60. I can turn 40's with one finger on my wheel when locked in 4 wheel drive on pavement.

it can be done!

[welndmn]

Hard locker? no such term, its just a locker
The TRD locker is electirc
the Jeep locker is air/electric, using only 5 psi to enguage it, only avil for D44's
The Gov lock is a posi, not a locker
A locker does not transfer power to the wheel with no grip, but transfers power to both wheels equaly
I will help fix more later

[peteyg]

Sometimes, an LSD will be referred to as a "soft locker", while real lockers are sometimes referred to as "hard lockers". That's all. Not trying to redifine a whole line of automotive products. Just making sure everyone knew where I was coming from.

As I have always understood it, the wheel off the ground is generating no torque. The instant it has traction it will have torque, but when it's in the air it's just turning. All of the torque is on the other wheel. It has to have something to turn against in order to generate torque. Perhaps we're just splitting hairs here. Would you be happier if I said both wheels have equal power, but the one with more traction is doing more work?

Gov-Loc is a locker, and an LSD. There is a counter-balance in there that locks the driver-side side gear to the spider gears, effectively spooling the diff when a certain speed differential threshold has been reached. That's a locker. I'll open one up and show you how it works. Scary stuff. I've disassembled a few of them. My Suburban has one, and it freaks me out every time it engages.

I always thought the Toyota locker was cable-select. Thanks for correcting that.

The Rubicon lockers are just for the Dana 44, true. But they are true air lockers. The electric part is the solenoid and a small electric pump. And yes, only 5 PSI for engagement. I haven't seen one fail yet, but the Rubicons are still mostly new. I didn't go into a lot of detail on that one because it doesn't really apply here in Ford land. Just thought I'd give them a mention, since I am a die-hard Jeep guy.

[reptillikus]

The Detroit True-Tracs are said to work exactly the opposite of an open differential. That is to say.....with one tire on the ground & one in the air, the one on the ground spins while the one in the air doesnt. When you have equal torque/traction/whatever on boty tires, both will spin equally.
I have one up front, and usually have both tires spin in mud, snow, sand and some mixes of the above. On rocks it doesnt work as great as a locker, but it still works well. I have been told of instances where ive had one front tire way up in the air, and it hasnt spun at all, while the one on the ground did spin. I cant confirm that however as i was in the truck driving at the time

[peteyg]

Originally Posted by reptillikus

The Detroit True-Tracs are said to work exactly the opposite of an open differential. That is to say.....with one tire on the ground & one in the air, the one on the ground spins while the one in the air doesnt. When you have equal torque/traction/whatever on boty tires, both will spin equally.
I have one up front, and usually have both tires spin in mud, snow, sand and some mixes of the above. On rocks it doesnt work as great as a locker, but it still works well. I have been told of instances where ive had one front tire way up in the air, and it hasnt spun at all, while the one on the ground did spin. I cant confirm that however as i was in the truck driving at the time

Right. That is the perfect definition of a Limited Slip, which is what the True-Trac is. It allows some of the power to go to the wheel with traction. True Tracs are great limited slips, but like you said, in rocks is where they really start to show their weakness.

[Marauder]

Thank you for this information. It cleared up a lot for me

[jopes]

Originally Posted by reptillikus

The Detroit True-Tracs are said to work exactly the opposite of an open differential. That is to say.....with one tire on the ground & one in the air, the one on the ground spins while the one in the air doesnt. When you have equal torque/traction/whatever on boty tires, both will spin equally.
I have one up front, and usually have both tires spin in mud, snow, sand and some mixes of the above. On rocks it doesnt work as great as a locker, but it still works well. I have been told of instances where ive had one front tire way up in the air, and it hasnt spun at all, while the one on the ground did spin. I cant confirm that however as i was in the truck driving at the time

i have wheeled in the rocks with a buddy whom has a true trac up front. when it lifts a tire in the front that tire spins while the tire on the ground does nothing. lsd's and open diffs suck.

[Andy351]

Originally Posted by MyFullSize

However, I have seen in plenty of 4X4 rags "Reader's Rides" that were big and built, and running big tires (33" & 35") with V-8s, and there running a LockRight in the rear, or both front and rear. I figure that has to say something for them?

and how many "readers rides" have you seen just sitting in a driveway or yard....

there is so much opinion being presented as fact here that it hurts my head....

[peteyg]

Originally Posted by Andy351

and how many "readers rides" have you seen just sitting in a driveway or yard....

there is so much opinion being presented as fact here that it hurts my head....

I have been trying really hard to present the info as straight as possible, based on what I know through real-world experience, as well as what I have seen in a wide variety of applications through the last 6 years of ever increasingly hard core wheeling. I have opinions on certain ways of doing things, and where I am presenting my opinion, I have tried to make sure I stated that it was my opinion. Some "facts" are subjective, of course, and there will always be the exception that proves the rule.

Where I have been wrong or missed things, I have added or corrected, and given credit where due. I think that's fair.

[Lonestar_Bronco]

Originally Posted by MyFullSize

Now, on the flip side. Running a LockRight with LARGE tires, were talking 33" and larger, with gobs of power turning it, were talking 351W or simililar/better, I cant attest to how well it would hold up. However, I have seen in plenty of 4X4 rags "Reader's Rides" that were big and built, and running big tires (33" & 35") with V-8s, and there running a LockRight in the rear, or both front and rear. I figure that has to say something for them?

I've wheeled with a '74 Blazer on 35" inch tires running a powertrax in the rear 12-bolt. With a stock 350 engine and 4.10 axle gears, he wheels the crap out of it. No problems with the powertrax, but he has torn up front spider gears in his open Dana 44.

[BlueBronco]

Originally Posted by Andy351

and how many "readers rides" have you seen just sitting in a driveway or yard....

there is so much opinion being presented as fact here that it hurts my head....

That's for sure.