28th January, 2015


I picked up the latest edition of ARB 4×4 Action mag when in at my local ARB store. What a great read! Love the pics, advice, tips and info. Keep up the excellent work!

Now, my question.

We have recently got back into four wheel driving after a long work-enforced absence. Cars have certainly advanced since our first fourby, an NG 1990 model Pajero, some 20 odd years ago!

We now own a 2009 NT Mitsubishi Pajero and we were wondering if there is a need for a diff lock (front, rear or both)? The Paj has MATT (Mitsubishi All Terrain Technology), ASC and ATC, which makes her quite capable off road.

Would the diff lock further enhance these standard features and give us some more confidence tackling some good spots?

I had a look at the ARB Air Locker in store. Good display model!

Anyway, I’d value your opinion and advice. Most of our driving is on bush tracks, sandy beaches and National Park trails (gravel, rocks, etc).

Many thanks,


Hi Sally,

Your MATT traction system is dependent on your Pajero’s braking system to force engine torque into the wheels with grip. It uses the same sensors and computer control that your vehicle employs for ABS braking—it detects when a wheel has locked up and reduces the braking force going to it in order to keep it spinning.

But as an off road traction aid, these sensors use wheel rotation to detect when a wheel is spinning due to slippage. When the system detects slippage, it uses an onboard pump to apply braking force to that particular wheel. This stops all of your motor’s power from escaping through the spinning wheel.

We are increasingly seeing brakebased traction aids available under various names by the different auto makers. These traction systems offer many advantages, but there are a few points to keep in mind when deciding whether to go the extra mile and equip your vehicle with Air Lockers:

1) As these brake-based traction systems use your vehicle’s braking system to generate the traction, they are also causing wear and tear to your brakes. The degree of wear and tear is proportional to the amount of assistance you get from the traction control system— so harder trails or more slippery surfaces are going to cause much more wear than street driving.

2) Frequent use of your brakes can also result in a high degree of heat being generated in your brakes. As you are not generally aware of the temperature of your brakes, the auto makers have integrated a temperature sensor, usually one in each wheel. When a dangerously high temperature is detected, your vehicle is programmed to shut off your traction control system until the brakes cool down to a safe level. At this point, you will be temporarily left without any form of traction control to help you.

3) Applying braking force consumes motor power; it’s an unfortunate law of physics. So everything you are getting in traction assistance, you are equally sacrificing in motor torque, and when off road you often find that you just don’t have any extra motor torque to spare.

This is especially true in loose sand driving where it is generally very important to keep the vehicle moving—however, your traction control system will detect wheel slippage in alternating wheels and apply your brakes accordingly.

4) It’s not generally the obstacles that you expect that get you into trouble… washouts from flash flooding, getting off the groomed trail because of damaged track signage, or extra deep ruts caused by heavy vehicle traffic are all too common examples of the unexpected obstacles that will bite you when you least expect it. There are a lot of things about any car that are not designed to cope with such conditions, but ARB’s Air Lockers were designed to cope with the worst that a trail can throw at you, so you’ll never need to worry about pushing them too far.

5) Turning on your locking differentials whenever things get a bit rough not only grant you the 100% traction that Air Lockers are known for, but it will also make your wheels rotate at the exact same speed. This therefore tricks your ABS computer into thinking that you are not on a rough surface and will stop applying any unwanted braking force, effectively switching your traction control system off automatically when it is not needed. This saves your brakes and motor power right when you need them the most.

In this way, we feel that Air Lockers and brake-based traction control systems are a perfect match.

– Daniel Bongard, Engineer
ARB Air Lockers