Last Saturday #CountryCyclist Ian Macleod went on the SA Adventure introductory off-road driving course at Hennops River, and went from zero to hero with the press of a switch
Stuck in a sandy crevice, in a vehicle some three times larger than my daily runabout, managing only to roar the voluminous engine and spin the tires. That was my dilemma on the trickiest obstacle of my first off-road driving course last Saturday.
“What do you have turned on?” inquired Tim Skelton, our instructor for the day. I was using all the diff lock I had, but that meant traction control was turned off (more on that later). “Turn off your rear diff lock. You need traction control for this,” came the advice.
I pressed one button. One light on the dash was replaced by another. Deep inside the mighty Toyota Prado, however, a transformation had quietly happened. The traction control system determined that the right rear wheel was achieving little, struggling for traction. It briefly applied the brake just to this wheel, redeeming the power it was wasting by spinning it on the sand.
With the flick of a switch – I’ve since taken to calling it the ‘hero button’ – the Prado’s growl was accompanied by a gratifying dose of thrust. The heroic machine hauled me up the rocky slope, but that didn’t stop me feeling like a 4×4 master.
Tim explains diff lock simply enough that a city slicker like me gets it. “It locks the wheels so they turn at the same speed,” he says. “Depending on your vehicle, you can lock the rear axle, front axle or lock the central diff between rear and front wheels.” It’s that simple.
Why? This helps make use of all the traction you can muster. An open rear diff, for example, lets a left tyre with less grip spin faster than a right tyre with more grip. Stopping this is of major use on slippery surfaces.
Traction control achieves the same result by opposite means. While diff lock is really a mechanical beast, this is more a software tool that works with sensors and the anti-lock braking system. Where one wheel loses traction – as with my right rear on last weekend – it can spin like the most powerful Katherine wheel without any benefit to you. In fact, it’s hemorrhaging power.
Traction control picks this up and automatically applies the brakes to the energy-sapping wheel. The result is more power available for the wheels that are finding grip. Very often that means you look like a hero, manoeuvring your 4×4 expertly out of danger. Cue applause.
5 other basic rules of off-roading:
1. Go as slowly as you can, but as fast as necessary.
2. Seek high ground. Pick the line that keeps all four wheels as high as possible.
3. Reduce tyre pressure to suit conditions. Rocky terrain needs 1.4 to 1.8 bar. This helps the tyres mound over rocks. Soft sand needs as little as 1 bard. This flattens the bottom of the tyre, meaning more surface area and less cutting in.
4. Hold your thumbs outside the steering wheel. Obstacles can force the steering wheel on a rapid spin.
5. Respect the route: no booze, just as much litter and as little noise as possible.
*Tim and SA Adventures are leading a self-drive expedition to Vic Falls in June. Best of all, Country Life readers get 10% off! Click here to find out more about this fantastic opportunity.