• Thewhiteox

Harrop E-Locker Install

An quick and easy explanation of how a differential works, why a diff lock is essential for serious four wheel drivers, and why we chose Harrop.

The final exciting addition to the Ox before we hit the road, was a new Harrop E-locker for our rear diff. We chose Harrop, partly because again, they’re an Australian company, but also because they have a well proven and very tough design. After weighing up all the pros and cons, we decided that an electric solenoid activated locker was ideal for an overland vehicle as opposed to the air locker designs which have additional complexity and air line reliance and have a tendency to blow out seals and pressurise diffs, and the slight delay that E-lockers have in engaging & disengaging is not as issue for us, as it can be for competitive vehicles or serious rock crawlers. Our primary consideration is always ultimately reliability, which usually means simplicity. 

A quick explanation for anyone unfamiliar: a 4 wheel drive like ours can be put into 2WD or 4WD. When we engage 4WD through the transfer box we're locking the front and rear prop shafts together, meaning both differentials are getting power from the engine and turning the wheels, and therefore giving us more traction and power for uneven or loose tracks. 

However, the differential can be a problem in really tough situations, because it works by sending the MOST power to the wheel with the LEAST resistance. That’s great (and essential) when you’re driving along and taking a tight corner when the tyres need to be spinning at different speeds on the track. 

But it also means that when one wheel is in a deep rut and the other is lifting off the ground, the diff is going to give ALL the power to the lifted wheel: not real good. 

That’s when you want a diff lock, which for us means both our rear wheels will be locked together, spinning in unison, with the same power going to both wheels at once. Now, in that same theoretical situation where one of our wheels is in a rut, it’s getting the power to push out of the rut and onto solid ground. 

It’s a must for any serious overlanders taking on tough remote tracks, and we’re really excited to have it installed! 

We haven’t got many photos I’m afraid, we were also packing up all our worldly possessions to relocate so it was a bit of a rush. We handed it over to Cape York Automotive to install and get the crown wheel and pinion backlash just right, who also completely rebuilt our whole diff with new bearings, crown wheel etc, making it virtually a brand new diff. 

We did however, install the electrics ourselves. Initially we wanted to have the switch only able to engage when 4WD was engaged, but it turns out that that wire has constant power. So instead we installed a second switch so that it couldn't be turned on accidentally in the middle of a sealed road. That was also when we wired up our aux fuel tank, and during the tinkering process, also had to replace our oil pressure gauge. We certainly got very familiar with the inside of the dash through the exercise, and used it as en excuse to reseal the air con ducts with new foam (should we ever decide to use them) and give it a general dust out.


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