Diff locker options; what types are there?

If there is one modification that is going to make your 4WD go much, much further, it’s a diff locker. I’ve seen some very plain, unmodified vehicles with diff locks go so much further than those with big tyres, suspension kits and other gear.

In fact, I recall a hilarious situation down south not long after I twin locked our 80 Series Land Cruiser.

Two vehicles in front of me struggled for some time to get up a short, steep hill climb in the dry with a couple of big offset wombat holes.

They both had lift kits, mud terrain tyres and competent drivers. Eventually they both gave up, and I crawled up in first gear low range with very little wheel spin, on 4 very average tyres and no lift at all. When should you use a locker? When there’s a good chance of slippage!

Ruts at Black Diamond
Big offset holes make it very hard for unlocked vehicles

Locking the two wheels together on your axles is a hugely worth while modification, and there are a number of ways that you can go about it.

Of course, these are not available for every single model 4WD out there, but there are a number of diff lock options.

In general, lockers will fall into one of the below categories:

Air (Pneumatic) Lockers

Air, or pneumatic lockers have been a common modification for many years now. ARB were one of the original companies to release a pneumatic locker, and they’ve been in use for thousands of vehicles all over the world.

You need a compressor, which pushes compressed air to engage the diff locker. Historically, these were pretty reliable when fitted by a decent technician.

The most common complaint though, is air leaking past an o ring and the locker not engaging. I can tell you from experience that having a locker that doesn’t work when you need it to is incredibly frustrating.

The trick here, is to get them installed by a quality technician.

Electric Lockers

Electric diff lockers are becoming more and more popular, and are engaged and disengaged simply by providing 12V power to the unit.

In many cases, they run an electromagnet which is activated and deactivated as needed, to make the differential lock and unlock.

Both lockers that we had in our Land Cruiser were Electric, and were made by Harrop Eaton. You can read about them here – Eaton Harrop Elocker Review.

E locker switches
E locker switches in our 80 Series Land Cruiser


The cheapest, and most simple locker is an auto locker, which is 100% mechanical and just locks the two wheels together when any slippage is detected. This means that it can lock when driving around a corner too.

They are the cheapest, and generally considered to be the least controllable as you have no control over when they lock and unlock, just that they will.

These have their place, but I’d be careful fitting them to vehicles that are already quite fragile in terms of the driveline, as they can apply stress when you don’t want them to.

Who makes differential lockers?

There’s quite a few companies that make and sell diff locks:

ARB, TJM, copies of ARB, Harrop Eaton and there are a number of 4WD’s coming to the market today with factory lockers already installed (at least in the rear).

Front ELocker
Diff locks make these sorts of challenges easy

What does a diff lock cost?

On the cheap end of the scale, you can get some auto lockers for a few hundred dollars.

ARB Air lockers start off at around the $800 mark, and Harrop Eaton Lockers around the $1800 mark. These prices exclude the cost of installation.

Diff locker fitting cost

Some diff locks are quite quick and easy to install, and others take a lot more time. If you have floating axles, you can simply drop the tail shaft, remove the rear axles and the differential will unbolt very quickly.

However, if you have a modern 4WD with IFS there’s a lot more work that goes into getting the diff out of the front.

In this instance, time directly translates into money, which is why you’ll pay more for different types of locker installations. The fitting cost can be anywhere from about $500 – $1000.

What’s the best diff locker?

I’ve long since given up the idea of one item being the best. If it suits your intentions and purpose, you’ve got what you need.

ARB and TJM Lockers have a good reputation (when installed well), and the Harrop Eaton ELockers are also extremely popular, and are probably my pick of the bunch.

I probably wouldn’t install an automatic locker, but a lot of people do and are happy with them.

What locker do you run? Are you happy with it?

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  1. Hey James,

    All of the auto lockers work in the same way, and they absolutely do work, and do a decent job for the price.

    They won’t engage when going around a corner anyway, unless you make the vehicle slide.

    I would seek real life feedback from those who own them, and not pay too much attention to what is promoted by 4WD magazines (at least take their promotions with a grain of salt). Every week they have a new product to push, and its not done for any other reason other than making a dollar.

    It all comes down to the sort of driving that you are doing, and your budget. I don’t think I’d want a locker engaging without me asking it to, but some people are happy with them

    All the best

  2. Hi Aaron,

    When you think auto lockers are risky, are you referring to the LOKKA would appear to be the main automatic brand? https://4wdsystems.com.au/lokka/

    I’m thinking of putting one in my front Colorado diff – https://www.youtube.com/watch?v=Xex9hOBwjUs. 4WD mag seemed to rate them, and said when not in 4WD the front diff isn’t engaged so no risk of it engaging around a corner on the road normally…?


  3. Hi William,

    It should not lock up going around corners unless you give it a bootful and make it slide.

    I would get some feedback from others with auto lockers before you commit to it; not a small install if you aren’t happy!

    All the best

  4. Hi i am thinking of installing 2 automatic diff locks to my 79 series to get a bit more traction.
    Will the diff locks engage when i am driving around corners and if they do what will happen