Differential Lockers: Front or Rear?

[Disc04]

Like a lot of you out there slowly building your rigs, I don't have an unlimited flow of cash to do everything at once. With that said, I wanted to post a question and get all of your opinions. I want dif lockers but won't be able to do both at the same time.

If you could only choose one locker kit, would you go with the front or rear? What brand? Why? I look forward to hearing from everyone. Thanks.

 

[CDN Offroader]

I'm not sure how the power is broken down on the Disco, but the FJ has a 40% front/60% rear split. Mine came with an e-locker in the rear and A-trac up front, I would say that makes more sense because of the power split. maybe doesn't matter as much if you have a 50/50 split though, although I would think that generally the extra strain of the locker would be handled better by the rear diff( no steering, cvs etc to break)

I can't really help you out with brands though. A lot of FJ guys run the ARB airlockers, but I don't have any personal experience with them.

 

[Rusty burbin]

Let me say right off the you always do the rear first! There are several reasons for that but mostly because you need traction more going up hill than going down and the weight distribution is more to the rear.

There are several options on the market in terms or brand and type... full-time, selectable, air, electric, limited slip is another option that can be very effective.

Your question is hard to answer without a bit more information like your budget and vehicle -
GVW?
Wheel base?
Tire size?
Horsepower?
Daily driver or trail rig?

Here are some rules of thumb.
Short wheel base rigs would benefit from from a selectable locker to help limit tire chirp and wear, and "streetability" longer heavier vehicles are fine with full-time locers... I drive a suburban and my full-time detroit locker is almost unnoticeable... put my locker in a 2 door jeep or Suzuki it would be hard to turn under power and it would click or chirp like mad.

If you can afford a selectable I'd go with 1st an ARB because they are incredibly strong and reliable but they require an air compressor because it is an air actuated system. This air compressor can be awesome to have for other reasons like airing up tires on the trail. Combin it with a tank and you can actually run an air impact gun for fast tire changes! If you get an air leak somewhere it can be a hassle to fix on the trail though. Eaton E-lockers are awesome too and won't get air leaks... but no compressor.

For a full-time locker a detroit is king... strong, no maintenance required and easy to install plus they have been around for ever.

I don't know if this is helpful or not but hopefully it helps give a little direction.

Rustyburbin from SoCal 5 kids, wife, dog and a 1970 K20 Suburban

 

[Disc04]

Let me say right off the you always do the rear first! There are several reasons for that but mostly because you need traction more going up hill than going down and the weight distribution is more to the rear.

There are several options on the market in terms or brand and type... full-time, selectable, air, electric, limited slip is another option that can be very effective.

Your question is hard to answer without a bit more information like your budget and vehicle -
GVW?
Wheel base?
Tire size?
Horsepower?
Daily driver or trail rig?

Here are some rules of thumb.
Short wheel base rigs would benefit from from a selectable locker to help limit tire chirp and wear, and "streetability" longer heavier vehicles are fine with full-time locers... I drive a suburban and my full-time detroit locker is almost unnoticeable... put my locker in a 2 door jeep or Suzuki it would be hard to turn under power and it would click or chirp like mad.

If you can afford a selectable I'd go with 1st an ARB because they are incredibly strong and reliable but they require an air compressor because it is an air actuated system. This air compressor can be awesome to have for other reasons like airing up tires on the trail. Combin it with a tank and you can actually run an air impact gun for fast tire changes! If you get an air leak somewhere it can be a hassle to fix on the trail though. Eaton E-lockers are awesome too and won't get air leaks... but no compressor.

For a full-time locker a detroit is king... strong, no maintenance required and easy to install plus they have been around for ever.

I don't know if this is helpful or not but hopefully it helps give a little direction.

Rustyburbin from SoCal 5 kids, wife, dog and a 1970 K20 Suburban

That was helpful. Thanks.

 

[4xFar Adventures]

'01 D2 owner here. I'm running Ashcroft HD axles front and rear, including cv's. The diffs are re-geared to 4.14 with the "diff peg" in the housing, front and rear. The rear has a Detroit Locker, and the front has an Eaton (Detroit) Truetrac.

I waited a looong time to get everything and then installed it all at once. Rear axles were purchased first, the fronts maybe a year later. Then after a good tax return the next year I bought the diffs all setup from Bill at GBR.

When you're at the point of getting lockers, you really need to upgrade the axles at the same time. That's also when you want to decide about the gearing in the diffs. What size are your tires currently? Or more importantly, what will be the final size of your tires? That will determine what ring and pinion to get.

I was going to just throw in the rear axles when I got them, but it's really the diff carrier that is the weak point on the truck. Upgrading the axles and leaving the rest of the diff in stock form wasn't going to help anything.

Not having gobs of money to throw at it all at once makes it difficult to decide what you want to do. You may be tempted to just do one or two of those things, but if you change your mind later it's gong to cost a lot more than if you wait and gather your parts. How long can you take staring at all of those lovely parts but not have them on the truck? Hide them in the closet ;) You can save a little bit of money if you don't get the diffs pegged. But given what you'd be spending anyways, and the extra protection it offers, it was worth it in my book.

For the lockers themselves, I've had no complaint from either of them. I've had the rear lock up and clunk a few times on the highway, but that's more on how you drive. Usually it's when creeping in traffic and riding the brakes a little too long in a curve. Application of the brake is used to get a Detroit to lock up faster.

The Truetrac has always been quiet, but that's based more on how they work. It's actually really interesting to see the gears operate. Look up Torsen locker on YouTube. Actually, there's a really good video from Filthy Motorsports on YouTube where Ben goes over all of the types of lockers and shows how they work with demo units on the desk. Air, TT, Detroit, spool, Yukon, and a couple others. A friend has an RRC with Truetrac's front and rear.

The RD128 ARB air locker is ok, though I've seen and heard some issues. Mostly leaky air lines or compressor issues. The pin that locks it up only has a few mm of engagement. If you go air locker take into account the cost of the compressor, and wiring in addition to the unit itself. Ashcroft does make an air locker that seems to really address the short comings of the ARB, but of course then you have to deal with parts from the UK if something goes wrong. But they have a solid reputation and Justin a Lucky8 is really good at taking care of that stuff and getting you what you need pretty quickly.

 

[Rusty burbin]

'01 D2 owner here. I'm running Ashcroft HD axles front and rear, including cv's. The diffs are re-geared to 4.14 with the "diff peg" in the housing, front and rear. The rear has a Detroit Locker, and the front has an Eaton (Detroit) Truetrac.

I waited a looong time to get everything and then installed it all at once. Rear axles were purchased first, the fronts maybe a year later. Then after a good tax return the next year I bought the diffs all setup from Bill at GBR.

When you're at the point of getting lockers, you really need to upgrade the axles at the same time. That's also when you want to decide about the gearing in the diffs. What size are your tires currently? Or more importantly, what will be the final size of your tires? That will determine what ring and pinion to get.

I was going to just throw in the rear axles when I got them, but it's really the diff carrier that is the weak point on the truck. Upgrading the axles and leaving the rest of the diff in stock form wasn't going to help anything.

Not having gobs of money to throw at it all at once makes it difficult to decide what you want to do. You may be tempted to just do one or two of those things, but if you change your mind later it's gong to cost a lot more than if you wait and gather your parts. How long can you take staring at all of those lovely parts but not have them on the truck? Hide them in the closet ;) You can save a little bit of money if you don't get the diffs pegged. But given what you'd be spending anyways, and the extra protection it offers, it was worth it in my book.

For the lockers themselves, I've had no complaint from either of them. I've had the rear lock up and clunk a few times on the highway, but that's more on how you drive. Usually it's when creeping in traffic and riding the brakes a little too long in a curve. Application of the brake is used to get a Detroit to lock up faster.

The Truetrac has always been quiet, but that's based more on how they work. It's actually really interesting to see the gears operate. Look up Torsen locker on YouTube. Actually, there's a really good video from Filthy Motorsports on YouTube where Ben goes over all of the types of lockers and shows how they work with demo units on the desk. Air, TT, Detroit, spool, Yukon, and a couple others. A friend has an RRC with Truetrac's front and rear.

The RD128 ARB air locker is ok, though I've seen and heard some issues. Mostly leaky air lines or compressor issues. The pin that locks it up only has a few mm of engagement. If you go air locker take into account the cost of the compressor, and wiring in addition to the unit itself. Ashcroft does make an air locker that seems to really address the short comings of the ARB, but of course then you have to deal with parts from the UK if something goes wrong. But they have a solid reputation and Justin a Lucky8 is really good at taking care of that stuff and getting you what you need pretty quickly.

This is good advice and something to seriously consider... wait and accumulate the parts that will in the long run give you a better rig. I'm in that exact situation here. I'm planning on building an entirely upgraded driveline. Currently I I'm running a th350 trans with an np205 t-case. I'm going to build a 4L80e transmission with a 203/205 doubler. I have all the parts except for the transmission which is gonna cost as much as everything else combined!

I think ideally you want your "weakest link" to be your u-joints because they're cheap and easy to change. So the above mentioned axle upgrades and carrier upgrades are smart to do with the locker.

Pirate 4x4 is a good resource to scroll through for information on all this kinda stuff... it's a bit more of an advanced forum and doesn't regulate jerks well... I've seen some threads that get pretty heated and frankly very immature and vulgar. Not the norm though.

There is a simple and fairly accurate formula for figuring out what gear set you're gonna need after your final tire size is decided.

New tire size × old gear ratio ÷ old tire size = new gear ratio.

Example: you have 33" tires and 4.09 gears and you're going up to 37" tires. It looks like this...

37 × 4.09 = 151.33
151.33 ÷ 33 = 4.58xxxx

In that scenario the closest gear set would be 4.56 (depending on make and model)

This helped me when I was deciding what I needed.

Rustyburbin from SoCal 5 kids, wife, dog and a 1970 K20 Suburban

 

[Graeman]

The least expensive way besides welding the axle is the LockRight style that just replaces the spider gears and does not require any extra work or mechanical skill. I had them in both axles, but to put them in the front you really need locking hubs for use in 2wd. Dollar for dollar they can't be beat, as you can do both axles for under $900 by yourself in 1 day and the only extra money that you will spend is on new gear oil. The longer the wheelbase the easier lockers are on drivetrain.

 

[4xFar Adventures]

I agree about Pirate4x4. There's a Land Rover forum that can be no holds barred but the info there is top notch. "Use the search function!"

If you don't want to go through the posts on Pirate, start by reading some of the Billavista Bible.

http://www.billavista.com/tech/

 

[Disc04]

Thanks to everyone who has provided advice already. Lots of good info.

 

[Lindenwood]

Great advice already!

Dedinitely go rear first, but there is tons of info out there. What kind of offroading do you plan on doing, and what kind of street driving do you plan on doing? I am 99% set on Truetrac LSDs front and rear of my daily driven 4runner because I want the consistency in all conditions as well as the hassle-free operation (I have a compressor, but don't want such a significant offroad advantage tied to a relatively fragile system of electrical components and air lines).

 

[Disc04]

Great advice already!

Dedinitely go rear first, but there is tons of info out there. What kind of offroading do you plan on doing, and what kind of street driving do you plan on doing? I am 99% set on Truetrac LSDs front and rear of my daily driven 4runner because I want the consistency in all conditions as well as the hassle-free operation (I have a compressor, but don't want such a significant offroad advantage tied to a relatively fragile system of electrical components and air lines).

That's a great point. Thanks.

Sent from my HTC6525LVW using OB Talk mobile app

 

[Graeman]

I think for Overlanding purposes LSD's are the way to go - given that most of the vehicles are also daily drivers.

 

[theoutbackdream]

I don't own both, but I think the rear locker is more important.

Why?

I always see rigs have no problems getting their front end over and obstacle, but the rear end seems to have issues. Partially because there's much less weight in the rear to help it stay planted.

 

[4xFar Adventures]

Front lockers are usually something that gets engaged briefly, only when the locked rear isn't able to push you up the obstacle. The front will instead, help pull the vehicle up and over. The problem (more so with an air locker) is that your steering is almost locked and there's not much you can do until the diff is unlocked again. Rear lockers are used more often and for longer periods of time compared to the front.

 

[4xFar Adventures]

I don't own both, but I think the rear locker is more important.

Why?

I always see rigs have no problems getting their front end over and obstacle, but the rear end seems to have issues. Partially because there's much less weight in the rear to help it stay planted.

There's actually more weight on the rear in the situation you describe (assuming you're talking about climbing over an obstacle). The front suspension gets unloaded and there is little weight to push the tires onto the ground for better traction. So that means the rear needs to handle the increased weight but there's not enough traction and the wheels spin. With a front locker, and just a little bit of traction, it's able to assist the rear help it make the climb.

Here's a pic of my truck in that situation. Notice how compressed the rear suspension is compared to the front? And this isn't much of an incline.



In this case, there wasn't enough traction at either end, so all four wheels were just spinning in place. It's really quick, but at the 29 second mark you can see it in action.

 

[Rusty burbin]

One more thing to consider. If you live in an area that gets snow or you plan on doing much driving in the snow you will want a selectable locker! Full time lockers can be a nightmare in hard packed snow and ice... you end up in the ditch. I know it seems counter intuitive but with an open diff if one wheel spins the one that doesn't will keep your forward motion steady. In the same situation both wheels spin and it's the equivalent of trying to steer with your front wheels locked up.

So there's that. [emoji20]

Rustyburbin from SoCal 5 kids, wife, dog and a 1970 K20 Suburban

 

[Rusty burbin]

There's actually more weight on the rear in the situation you describe (assuming you're talking about climbing over an obstacle). The front suspension gets unloaded and there is little weight to push the tires onto the ground for better traction. So that means the rear needs to handle the increased weight but there's not enough traction and the wheels spin. With a front locker, and just a little bit of traction, it's able to assist the rear help it make the climb.

Here's a pic of my truck in that situation. Notice how compressed the rear suspension is compared to the front? And this isn't much of an incline.

View attachment 19785

In this case, there wasn't enough traction at either end, so all four wheels were just spinning in place. It's really quick, but at the 29 second mark you can see it in action.

Not to mention that as a vehicle approaches an obstacle in many cases you have 4 wheels on more or less flat ground so all the power is put to use getting the front end up and over said obstacle.

Rustyburbin from SoCal 5 kids, wife, dog and a 1970 K20 Suburban

 

[Lindenwood]

One more thing to consider. If you live in an area that gets snow or you plan on doing much driving in the snow you will want a selectable locker! Full time lockers can be a nightmare in hard packed snow and ice... you end up in the ditch. I know it seems counter intuitive but with an open diff if one wheel spins the one that doesn't will keep your forward motion steady. In the same situation both wheels spin and it's the equivalent of trying to steer with your front wheels locked up.

So there's that. [emoji20]

Rustyburbin from SoCal 5 kids, wife, dog and a 1970 K20 Suburban

This was kindof glossed over, but yeah you will definitely want selectable lockers or an LSD up front if you are planning on doing any regulaw AWD / 4WD street driving. This is part of the reason I am going with LSDs: when my wife and I move to NM, we expect to go skiing at least once a month during the winter. I want her to be able to drive my rig if necessary without weird surprises from front diffs locking and unlocking. And, like I said above, I am steeting away from selectables (i.e. ARBs) because I don't particularly want to tie such a significant offroad advantage to such a potentially fragile combination of air lines and electronics.

 

[Rusty burbin]

This was kindof glossed over, but yeah you will definitely want selectable lockers or an LSD up front if you are planning on doing any regulaw AWD / 4WD street driving. This is part of the reason I am going with LSDs: when my wife and I move to NM, we expect to go skiing at least once a month during the winter. I want her to be able to drive my rig if necessary without weird surprises from front diffs locking and unlocking. And, like I said above, I am steeting away from selectables (i.e. ARBs) because I don't particularly want to tie such a significant offroad advantage to such a potentially fragile combination of air lines and electronics.

That's a good plan. Very streetable and it should work gangbusters offroad too. Keep us posted as you move forward.

[emoji106] [emoji106] [emoji106]

Rustyburbin from SoCal 5 kids, wife, dog and a 1970 K20 Suburban

 

[The other Sean]

This was kindof glossed over, but yeah you will definitely want selectable lockers or an LSD up front if you are planning on doing any regulaw AWD / 4WD street driving. This is part of the reason I am going with LSDs: when my wife and I move to NM, we expect to go skiing at least once a month during the winter. I want her to be able to drive my rig if necessary without weird surprises from front diffs locking and unlocking. And, like I said above, I am steeting away from selectables (i.e. ARBs) because I don't particularly want to tie such a significant offroad advantage to such a potentially fragile combination of air lines and electronics.

LSD's can also give some spooky handling at highway speeds. Been there, done that...