Shift on the fly 4WD; how good is it?

A lot of 4WD’s operate in 2WD for majority of their life, and to get the front two wheels to drive you have to engage 4WD. This can be done in a variety of ways, but the original way was with manual locking hubs. Some 4WD’s are constant 4WD, and just lock a centre differential as needed to get to 4WD high range.

However, there are many 4WD’s today that can go from 2WD (or AWD) to 4WD high range by just turning a dial, or pressing a button. Our Isuzu Dmax has the ability to swap between 2WD and 4WD high range at any speed between 0 and 100km/h, and this is known as a shift on the fly 4WD.

I can’t tell you of how useful this, coming from a Hilux and Land Cruiser, that required you to get out and manually lock hubs, and be stationary or really slow moving when you change.

Part time kit 80 series
Manual locking hubs are reliable, but rather annoying

Ultimately, what this meant was that I often didn’t put it in 4WD when it should have been, purely because I didn’t want to pull up to a stop, engage 4WD and then get going again. Gravel roads for example, often were done in 2WD instead of 4WD, which meant less traction, and more wear on the tyres.

The rear tyres on my Land Cruiser were substantially further worn than the fronts after a 9000km trip to the Kimberley, purely because the rear wheels were pushing 3 tonnes of 4WD up and over nasty gravel roads, without the assistance of the front wheel.

KM2 Mud Terrains
Our BFG KM2’s got hammered in the Kimberley

With the Isuzu Dmax now, you just turn a knob as soon as you go onto any other terrain than real hard gravel or bitumen, and a few seconds later 4WD is engaged. It makes things a breeze, as I no longer have to stop even for half a second to engage 4WD. Now, every gravel road is driven in 4WD, which is safer, better for the 4WD and reduces the tyre wear!

4WD on the fly
Turn the knob and you have 4WD on the fly

When should you use 4WD high range?

For high speed driving, high range is the perfect choice. This includes driving on gravel, or surfaces that are uneven and slippery. You should never be in 4WD on a bitumen road, unless its constant 4WD with the centre diff lock engaged.

When should you use 4WD low range?

Low range on the other hand is used for slow, high torque applications. This means rock crawling, mud and most beach driving (unless its like concrete). To get to low range you do have to come to a complete stop, and many 4WD’s require you to be in neutral as well.

This is less of an issue, as you usually come to a stop before needing low range anyway!

Low range on the beach
Low range is best for soft beach driving

For us, a shift on the fly 4WD is mainly useful when coming on and off gravel roads often, and not having to stop at all.

How do you engage 4WD? Would you love to have 4WD on the fly?

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  1. Hey Howard,

    Yep, it is amazing. I’ve seen a few people shift as you discuss in older 4WD’s, but not too many people know about it.

    All the best

  2. Howard Green says:

    We love 4wd on the fly for the same reasons as you, better traction, less wear and tear on tyres, better breaking, etc.
    4wd on the fly has been around for around for longer than many know. Shore, for those “upmarket” 4bys of yesteryear that had free wheeling hubs you’d have to stop and get out to lock them in but if you kept them locked or had what some of us called “solids” on the front (the solid drive flange that was there instead of the free wheeling hub) you were able to shift from 2wd to 4wd without slowing very much at all, even on dirt roads. All you had to do was hold a slight pressure on the 4wd stick as if you were ready to shift and let off the throttle a bit, she’d pop strait in. Same with shifting back to 2wd. We do it in our Pajero and our Jeep, we used to do it in our Vitara, Hilux, 40series, G60 and GQ Patrol, S3 landy and there’s probably more I’ve forgotten we’ve done it in.
    4wd on the fly, love it