Eaton Harrop E Locker Review

Diff lockers are nothing new. They have been around for many years, providing the ultimate increase in traction. The way the lockers work though, is continually being worked on. Today, I’d like to share with you a Harrop E Locker Review.

Now, in the interest of being completely transparent, you deserve to know that Harrop supplied us with two lockers for the price of one a number of years ago, which I paid to have fitted into our 80 Series Land Cruiser. I was going down the path of E lockers anyway, and was only going to get one, but ended up with two which made it almost unstoppable.

We’ve since installed a new Harrop E Locker into our Isuzu Dmax, which we paid full retail price for, and were completely happy to do so.

Differential lockers
Need more traction?

What are diff locks?

Before I go into Eaton Harrop E Lockers, we must first look at how a differential works. For most 4WD’s, open diffs are standard. This means that the axles on either side of the differential are not locked together (in other words, both wheels can rotate at different speeds, which is required for going around corners!). 

The power from the engine will always go to the wheel on each differential with the least resistance, which is often not ideal when four wheel driving.

When we are off road, this usually means that the wheel with all of the weight on it (and the most traction potential) sits there doing nothing, whilst the other wheel on the axle spins like crazy. In a 4WDing application, often one wheel on each differential will spin, and the other 2 will not. This is known as being ‘crossed up’ and results in your car not moving at all!

A locker simply locks both axles on the differential together, so the wheels are forced to rotate at the same speed. This ensures that regardless of how much weight your tyres have on them, the wheel will continue to spin.

Do you have an LSD?
Loose hill climbs are the perfect place for lockers


LSD’s, or limited slip differentials make use of a clutch between the two axles. The idea is that when one wheel stops driving, the clutch attempts to make the other wheel continue to drive. For most Toyota’s, the LSD’s are worn out within 20,000km and are virtually useless. Nissan make great LSD’s which work quite well, but an LSD will never be as good as a locker.

Types of lockers

It’s well known that a locker (or 2) will make your vehicle considerably more capable. However, as I mentioned above, there are plenty of different types; air lockers, electric lockers, auto lockers and mechanical lockers. Finding the best diff lockers really depends on your budget, who’s fitting it and what quality you want to get.

Air lockers are engaged via compressed air, and the most well-known are made by ARB and TJM. Auto lockers engage automatically when they detect wheel slippage, and are made by a number of different manufacturers (Lokka, Detroit and Lock Right).

Electric lockers are engaged with the use of an electromagnet. They require 12v power, and that’s it!

Why fit lockers?

The primary reason for fitting lockers to a 4WD is to maximise the available traction. There is no point having huge tyres, a big lift kit and a massive engine if you aren’t able to translate this into traction. By having twin lockers, all 4 wheels rotate at the same speed, and give you the most traction possible.

Diesel smoke isn't great
All the power in the world wont get you far without traction

It would seem then that the only need to fit lockers is for extreme four wheel driving, but this isn’t quite correct. Lockers allow you a significantly greater control of your vehicle. When you approach an obstacle, there are a number of ways you can attack it:

–          Idle up slowly and see if your vehicle makes it. If it doesn’t, you need to back down and try again, which isn’t always easy or safe.

–          Give it a boot full and hope for the best. This often works, but will eventually lead to something breaking.

–          Engage the locker (s) , and drive up knowing you have the most possible traction. This is the best choice as it looks after your four wheel drive and the tracks, whilst giving you the best chance of getting through the obstacle.

Sure, you can do without lockers, but in many applications to overcome the lack of traction you must attack the obstacle with more speed. This is ok in some cases, but it will inevitably put more stress on your vehicle and lead to breakages eventually.

Eatons Lockers
Impossible hill climbs are made possible with E Lockers

With lockers, you can approach any obstacle slowly and carefully, knowing that you don’t have to worry about wheels sitting stationary. This is especially important on hill climbs, where a loss of traction can cause significant problems!

Harrop E Lockers

Eaton Harrop E Lockers have been designed to suit a number of 4WD vehicles, and new models are being brought out on a regular basis to suit our ever changing 4WD industry. They are simple, easy to install and have been proven in hundreds of four wheel drives, from the family touring vehicle through to competition spec winch vehicles.

E locker switches
Instant traction buttons

I installed front and rear lockers to my 80 Series Land Cruiser, and have been absolutely blown away by their performance. I know that when I get to a difficult situation, rather than using momentum to overcome the obstacle I can put one (or both) lockers on and drive through it in a much more controlled manner.

Harrop have been in Australia for 57 years, manufacturing and designing everything from superchargers through to race car driveline parts. They have a solid reputation, and partnered with Eaton to bring the E Locker to Australia.

Eaton are even bigger, and have been manufacturing in the Aerospace, Automotive, Electrical, Hydraulics and many other industries for well over 100 years. Together, the Eaton Harrop E Locker has a very solid foundation!

Advantages of the Harrop E Lockers

Eaton Harrop E Lockers are simple. They have two wires running to the differential, and a switch that activates them seamlessly. They are extremely quiet (when I fitted them to the differential, we tested them out of the vehicle, and had to do it twice because we couldn’t even hear them engage!)

Traction via an electronic locker
Simple, traction on demand

The simplicity makes it easy to repair should anything go wrong in the bush; if a stray stick or rock break your cable in half, you simply join a new section in. The plugs are all completely dust and waterproof, and the unit is built with some serious engineering thought behind it.

Eaton lockers don’t require the use of a compressor, which means you don’t have to run one to engage the locker, and you don’t have to plumb it all up.

Harrop E Lockers price

Eaton Harrop lockers retail for around $1500 – $1900 each, depending on the make and model of your vehicle. Fitting is on top of this, and is usually around $400 each, or you can do it yourself.

In 2022, I had Coastal 4×4 install a rear Harrop E Locker into our Isuzu Dmax, with new bearings for just under $3200.

Can I fit it myself?

If you are familiar with differentials, fitting Eaton E Lockers should be no worry. However, Eaton recommend getting a differential specialist to do the installation if you have never installed a diff before.

Each locker comes with extensive instructions, and it’s just a case of removing the differential, swapping the differential carrier, replacing the bearings, checking the backlash, drilling a hole in the differential housing and completing the wiring to the dashboard (where your switches are mounted). This will take at least a couple of hours per differential.

In my case, I was comfortable removing the differential, but less comfortable replacing the carrier and bearings, and got Perth gearbox differential and clutch center to install the lockers. They did a great job, and then we tested them and installed the differential back in place.

Front or Rear lockers?

This is one of the questions that you can spend hours arguing about. If you have an LSD that works well, it is a good idea to fit the E Locker to the front of the vehicle. However, a locker will work more effectively on the rear, as you mostly need them when climbing up hills, which puts all of the weight on the rear of the vehicle. If you want to know more about this, we go into a lot more detail here – Front or Rear Locker?

Confidence through lockers
How confident are you?

Where can I get them from?

Harrop distribute their E Lockers through Terrain Tamer, Harrop Traction Dealers and Opposite lock. There are plenty of these scattered across Australia. You can find a full list of dealers for the E Locker here.

Harrop E Locker Review

So, onto the nitty gritty. I had two of the Harrop E Lockers on our 80 series for a number of years before I sold it, and they were flawless, and made the vehicle from fairly capable, to incredibly capable, and probably well beyond my ability as a driver.

Since then, we’ve been running a rear Harrop E Locker in our Isuzu Dmax for nearly 30,000km on our Big Lap of Australia, and its been used a number of times, giving us a much greater level of confidence, and reliability as it stops the diffs from chewing out, which is a common Dmax Problem. You can read more about this at Dmax Rear E Locker.

We’re really pleased with the product, and wouldn’t hesitate to buy them again. 


If you are looking for solid, simple and reliable lockers, then the Eaton Harrop E Locker is well worth buying. I’ve used mine a number of times now, and have been very impressed. Just flick the switch and you have instant maximised traction. Here’s 7 reasons why I love my E Lockers.

Lockers by Harrop
It all pays off!

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  1. Hi Warren,

    That isn’t true. They require a little wheel rotation to engage (maybe 1/4 turn), but they will engage in any situation. Ideally you don’t punch it when they are trying to engage or you can break things, but there’s no issue with them engaging when you are stuck.

    All the best

  2. Warren Peers says:

    I have heard that you can’t engage these lockers if you are already stuck, so say if beach driving, one wheel is bogged, the other just spins, its too late to engage the locker? or going up a hill, and one wheel is in a hole. Is this true, or should I just be able to stop, engage the lockers and they should engage no problem?

  3. Hi Luke,

    You are correct that the LSD has to come out, but I can’t think of any reasons where you’d need one on the road. If your vehicle has ESC its going to help out if you lose traction anyway.

    I will be doing a post soon, but I would go a rear locker any day over a front one. You will need the locker in 90% of cases when going up hill, which is when you have majority of the weight on the rear.

    Lockers can put extra stress on your CV’s if you drive roughly. If you are careful, they should reduce wheel spin and the chances of a wheel coming down hard while spinning, which is what usually breaks a CV.

    All the best

  4. Interested in one of these lockers, however concerned that installing in the rear of my vehicle removes the LSD. Which is fine for off road as the locker will be in use, but does that decrease the safety of my vehicle in everyday road use? Also, I’ve heard that front lockers can be hard on the CV joints? Front or Rear.. bit of a tough choice…

  5. Hi Craig,

    You’ll have to ring a distributor mate. This is just a review. We don’t sell them

    All the best

  6. Hi I’m interested in a e locker for a mn 2013 triton Glx 4×4
    Price etc

  7. Hi Phil,

    It doesn’t matter what type of locker you use, steering will be affected to some degree. You barely notice it on the rear, but you will absolutely notice it on the front. In general traction is preferred over steering, so you put up with it!

    All the best mate

  8. Phil Roberts says:

    Is steering effected when using this diff locker

  9. Grant Page says:

    can you fit a e-locker on the front of a 1996 land cruiser that all ready has a air locker on the rear.

  10. Kayne Moore says:

    Ok thanks

  11. Kayne Moore says:

    Do they make a front and rear elocker for 2000 model Rodeos 2.8L diesel