Clearance: Rise above the obstacles
Superficially and practically speaking, the difference between a 4x4 and a hatchback, saloon or estate is the shape. Off-roading vehicles are usually taller, and a lot of that height comes from their ground clearance. Basically, that’s the distance between the ground and the bodywork of the car. In a more real-world sense, it’s the three angles at which the body of vehicles intersects with a given obstacle, the approach, breakover (between the front and back axles) and departure angles.
You might think that higher clearance comes from bigger tyres, and while that’s part of the story, it’s also affected by the suspension. Another factor which plays a role here is articulation, which is the ability of the two wheels on an axle to move up and down relative to one another.
Tyres: Put the power on the ground
You can have the biggest engine in the world, the fanciest gearing and suspension system, whatever. At the end of the day, the ability for a car to move comes down to the interaction between the tyre and the surface below it. Off-roaders of all kinds - cars, bikes, quad bikes, etc. - need big tyres (unless they have tracks). This is because tracks and trails lack the uniform grip of a tarmacked road. Mud, gravel, wet grass and other off-road surfaces lack traction, but tyres with big grooves and ridges in them will be able to take advantage of what little there is.
Bear in mind that fitting a set of all-terrain tyres isn’t the end of the story. Tyre pressure is very important. To take on tricky terrain, you’ll want less air in them so that they can mould themselves to the uneven surface and generate more friction.
Differentials: Make your wheels work together
All cars have differentials. They’re essential for effective cornering, allowing the outer wheel to travel faster when going round a bend than the inner one by sending more power in that direction. Sometimes though, especially in off-road situations, that’s not what you want. If you’ve got one wheel spinning freely in mud, there’s no point sending more power that way. Having a locking differential means that you can force both wheels on an axle to turn at the same rate, which can get the power to place where there’s traction.
One step further than that, four-wheel drive systems allow you to essentially lock the front and back axles together, so even if only one of your wheels has any grip, it’s guaranteed to receive power from the engine.
Gears: One for every occasion
The series of cogs in a gearbox, the gears, change the way that power is transferred from engine to wheel. High gears allow a smaller power input to result in larger output, lower gears allow more torque, the driving force, to be sent to the wheels when the going gets tough. These are what you need when off-roading, to keep the wheels turning (avoiding stalling) when the wheel has to work hard to clear obstacles.
But the thing that 4x4s do that’s important isn’t just going off-road, it’s going both on and off the tarmac. In order to switch between the two, 4x4s have a low-range transfer case alongside their standard gearing, almost like a separate gearbox especially for off-roading. If you ride a bike, think of switching to low-range as changing down on the front derailleur (the cogs housed near the pedals).
Software: Where things get complicated
Everything so far has been hardware - stuff you can see, touch, take out and put back in with tools and elbow grease. Any off-roading vehicle built in the last 10-15 years, however, is going to come fitted out with high-tech gadgetry and computer programming that aims to put the physical parts of the car to the best possible use. A lot of amazing things can be done with these intelligent systems, but some critics complain that they’re either just hype for marketing purposes or a cheaper way for a manufacturer to boost their product's off-road credentials compared to improving the actual nuts and bolts of the machine.
Jargon and space-age names abound in this field: Quattro, 4Matic and Super Select to name but a few. It’s not our intention to get into the details of what these systems actually do, but we will give you two pieces of advice. First, hardware always beats software. It’s common sense - you can put all the computer power you want into a hatchback, but it won’t have anything on an old jeep on uneven terrain. Second, AWD, or all-wheel drive, is not the same as 4WD. Favour the latter.
Accessories: Add-ons, extras and customisation
If the word accessories makes you think about fashion, you might be reading the wrong article! We’re talking about bits of kit that will make your vehicle more effective in general, in certain circumstances, or in emergencies. From winches to pull you out of a tight spot to extra lights to improve your visibility and roof racks that let you take more stuff with you, there are plenty of things that can be attached to the bodywork of a 4x4 to make it a better off-roader.
Other items you might want to be carrying with you include sand ladders, which are placed under the wheels when the car loses all traction, spare tires, snow chains and a whole lot more.
If you book one of our 4x4 driving experiences, you’ll almost always get behind the wheel of a vehicle provided by the experience operator. While you don’t need to know exactly how the machinery works, a basic understanding of the challenges that off-road driving can present,and the solutions that manufacturers have come up with to allow their vehicles to deal with those challenges, will result in a more successful, enjoyable session.
