Why we fitted a Harrop Elocker, and how it performs

Differential lockers make a huge difference to the capability of your 4WD, and whilst traction control has come in leaps and bounds and is actually fairly impressive today, we’ve just had a Harrop Elocker installed the rear of our Isuzu Dmax.

Some of you will know we had two of these in our 80 series Land Cruiser, which took it from a fairly capable vehicle to one that would crawl up almost anything, only being limited by the traction the tyres could grab. I was always very happy with the Elockers, and this time we’ve opted for a single, rear one.

Like always, we believe in being transparent, and you should know that we paid full price for this unit, and go into the costings below.

Dmax rear locker
We’ve got a new rear locker, by Harrop
Harrop ELocker
Our new traction improver

Why the Harrop Elocker?

There were two main reasons for fitting a Harrop Elocker, and I’ll openly admit I put fitting it off for as long as possible. It was on the ‘want list’ since we built the Dmax, but we’ve always managed OK without it and after blowing a huge chunk of money on our Land Cruiser, I’m always cautious of over modifying. So, why’d we go with the Harrop Elocker?

I wanted a bit more capability

There’s no denying that our 80 Series Land Cruiser was a far more capable 4WD when the going got tough. Big ruts, offset holes and hill climbs were far easier in the Land Cruiser, and that’s not surprising when you look deeper into it.

The Dmax is far more comfortable, and a much more suitable vehicle for what we want, but there are times where its struggled, and with the addition of our Reconn R2 Hybrid a little bit of extra traction is hugely appreciated.

For 90% of the situations where we use our Dmax, it does just fine without the locker. You have to be careful with line choice, and apply the throttle with a bit more thought, ensuring that wheel spin is kept to a minimum (particularly the front), and as such we’ve never broken anything. 

However, on our recent Pilbara trip there were a couple of occasions where I’d have been much more comfortable with a locker, knowing how much additional traction they can provide. When you’re experiencing a lot of wheel slippage, or there’s a good chance of it happening, you know its time to use the locker.

Magic Pool Hill Climb
A locker would have been very useful here
Nasty climbs at Magic Pool
Anything with offset holes and a climb make traction control work really hard

Towing a trailer kills your vehicles capability to a level that is hard to explain, unless you’ve experienced it before. This is particularly the case on sharp hill climbs, where you can’t go too quickly, but your vehicle struggles to get enough traction to drive up. 

Traction control is good, but its reactive, and by the time it kicks in, you’ve already lost traction, and the valuable momentum that you had. We have a post that covers Traction control vs Diff locks, and goes into more detail.

The only counter then, is to lower your tyre pressures for more traction (which has its own limitations), or hit it with more speed. I’ve seen what excessive momentum does time and time again, and avoid it.

When the going gets a bit tough, I know that we have the best chance of making it up at a reasonable speed without excessive wheel spin and doing damage to the vehicle from it bouncing around, or sliding off track and copping panel damage. Some obstacles are quite hard to navigate back down from if you don’t make it, so finding the right level of momentum and traction is critical.

Mud terrain tyres are heavier
Our twin locked 80 series walked up this

So, the ultimate solution is a rear locker. A rear locker will generally get you where you need to go, with a front being a luxury that I decided we didn’t really need. The rear locker gives me much needed confidence, and regains some of the capability that is lost when you hook a 2.2 tonne trailer on the back! Want to know if its better to fit a Front or Rear Locker?

I recall being absolutely shocked at how much difference just the rear locker made to our 80 series, and have no doubt it will be similar for our Dmax (perhaps even more so, as it has less wheel travel and clearance from the get go, further reducing its capability).

I wanted to replace the rear diff centre

There’s been a huge number of Isuzu Dmax and MUX rear differentials that have failed over the years, in particular between 2012 and 2019. I’ve been told there was a bad bad of hard facing, and have seen hundreds of photos of munched out rear differentials. They just seem to chop out, and once there’s a bit of metal floating around they start to chip, and fail very quickly. This is one of the better known Isuzu Dmax issues.

Dmax diff centre
The diff centre is removed and replaced with the Harrop spool

This has become such a big problem that its almost impossible to buy a second hand rear diff centre, and people are resorting to installing torque worms, or LSD differentials from earlier Rodeo’s. When I first heard of this issue you could get a second hand diff centre for a few hundred bucks. Good luck getting one today for under $1500, and that’s for one that might still flog out and fail.

With this in mind, it basically became a sensible decision to rip the differential centre out and replace it with a Harrop Elocker purely from the perspective that it was going to fail at some time, and you may as well spend that money on upgrading now, than having to put something old and second hand in later (and potentially mid lap of Australia, in a remote part of the world where things are even harder to make happen).

As it turns out, the pinion bearing was loose and we picked a pretty good time to do the Harrop Elocker install. We’d have paid a similar amount just to get a second hand unit put in if we were somewhere around Australia, and that was the final swaying decision.

Dmax diff centre wear
Our centre wasn’t too bad at all; I’ve seen them completely mushed up

Fitting the Harrop Elocker

I’ve always been quite cautious of who fits lockers, knowing that they need to be done well, with the correct clearance and backlash, and getting a general ‘accessory fitter’ to install them always seemed a bit backwards to me. Perhaps that’s the reason there’s so many leaking pneumatic lockers out there.

When we had our previous Elockers installed, I actually removed the differentials, and took them to a dedicated diff shop in Belmont, for them to do the install, and then a mate helped with the wiring of them.

Regardless, I was pleased to find out that Coastal 4X4 (who are just down the road), combined with WA Diff Centre, and they also had stock. I literally rang about 6 different 4WD stores, who didn’t have stock, and were quoting 12 weeks just to see the unit.

I found out Terrain Tamer had 3 Elockers in stock, and Coastals were able to book me in and have it done within a week (which was critical, as we were leaving in 4 weeks to go around Australia). 

Terrain tamer Elocker kit
Terrain Tamer had stock in Perth, which was helpful

Coastals were great to deal with, did a good job and kept the centre for me to have a look at (which was actually in pretty good condition). They picked up the loose pinion bearing, and replaced that, along with the seal and fitting the locker. Essentially, it got a full differential rebuild, with the clearances set perfectly. We couldn’t have timed it any better if we’d tried.

Harrop Elocker install
Installation instructions in the manual

Coastals did the drive in drive out service, installing everything in the one day, which made life much easier for me. They did receive a switch that didn’t suit our model, so I had to go back and get it swapped out later, but it wasn’t really their fault.

Rear diff lock installed
We’ve now got a rear Elocker

What did we pay?

The total cost including installation and the extra differential work was a whopping $3179. Yep, that hurts, a lot, but as I said earlier it’d cost almost that much to buy a second hand differential, rebuild it all and get it back on the road.

To break it down, the locker was $1785, 6 hours labour at $140 (2 extra due to the pinion bearing) and the rest was bearings, oil and the pinion seal. Terrain tamer wanted $1896 just for the locker, so it was cheaper to get it through Coastal 4×4.

It still wasn’t cheap, and I have no doubt I could have haggled and got a better deal (or gone for a sponsored setup), but I hate doing that these days.

Elocker in our Dmax
Expensive, but entirely justifiable in my mind

Why not get a different type of locker?

Despite not really being a fan of the ARB air locker (more to do with bad installations than the actual product), I did price one up. It was $1198 for the locker, $650 to fit it, plus a compressor, which was $435 fitted, or $795 fitted for the larger one. They were also not available until after we departed.

I did consider the TJM Pro Locker, which has a good reputation, but we’ve had a good run with the Elocker and I quite like their design.

I wouldn’t get an auto locker, fitting an LSD to the Dmax is not legal as it interferes with the ESC system, and you can’t go wrong with a locker that you turn on when you need it.

Front ELocker
We had a great run from our twin Elockers in the 80 series

E Locker Review

We’ll be doing a heap of kilometres over the next year or two around Australia, and I know I’ll be glad of having fitted the Harrop Elocker.

EDIT – we’ve now had this fitted for the better part of a year, and done about 30,000km all over Australia, on some shocking trips. I’ve been incredibly glad of the rear E Locker on numerous occasions, especially with the camper on the back as it improves the Dmax capability so much, and allows us to tackle difficult sections at a lower speed, without relying on momentum (and breaking something) to get us through.

This, in combination with the Toyo Open Country RT tyres has made our Dmax substantially more capable, and its solved the reliability issue, so I’m very pleased.

Do you run a front or rear locker? What type, and do you like it?

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