Offroad driving

Besides from the obvious fact that all four wheels are driven and thus giving more traction, there are other important differences between a two-wheel and a four-wheel drive:

• Low transfer gearing: Needed to take steep, difficult terrain slowly and carefully
• Differential locks:
  • Centre differential lock: Must be locked immediately when driving through difficult terrain, because if it not locked and one wheel loses traction, all power will be distributed to this (now free-running) wheel. If the centre differential is locked, then two wheels have to lose ground contact for this to happen, and it must be one wheel from the front and one from the back.
  • Axle differential locks: Do not lock on tar (excessive tyre wear). May create difficulties on flat terrain where the surface is slippery, but traction almost the same for every wheel (e.g. sand), under-steer. The rear lock always has to be engaged before the front lock!

  Rule of thumb: Engage the centre lock immediately when leaving tar, engage axle locks only to get out of difficult situations.

• Higher clearance

• For all offroad driving remember:
  1. This track is not actually meant for driving. Doing so anyway requires experience and skill.
  2. That the road was passable yesterday does not mean it is today. Stretches now might be washed out, chipped away, or submerged.
  3. That the car in front of you can pass does not mean you can. It might have more ground clearance, better tyres, or less weight.
  4. That the guy in front of you can pass does not mean you can. They might have more experience, better nerves, or sheer luck.
• Responsible offroad driving is not what you watch on YouTube: Revving engines, taking obstacles at speed, bouncing off rocks. Responsible offroad driving is slowly maneuvering the track without loosening rocks, spinning tires, overheating the engine, or ever losing control.
• Always remember to wear a seat belt, even if driving at low speeds!
• Make it a habit to never brace yourself with a "roll bar", in the event you overturn, you may crush or lose fingers.
• Make sure your safety helmet has face protection. (Broken jaws are common.)
• Do not fight against the vehicle. Let the steering wheel slip through your fingers a bit and gently guide it on the ways you want.
• Never grip the steering wheel with your thumbs on the inside. Hitting a boulder or pothole at speed will cause the steering to turn fast and hard, resulting in a bruised, dislocated or broken thumb.

For all challenging terrain described here: Switch on your 4x4! Most vehicles that call themselves 4x4s or off-road vehicles, have this capability switched off by default. Even on a good gravel road the 4x4 should be active, not least because such roads deteriorate faster from 2x4 traffic. Differential axle locks, however, should only be activated once you are stuck, or on patches where you do not drive faster than walking speed (5 km/h).

• Gravel: Release tyre pressure to about 1.7 bar which will result in just about visible "pockets". Avoid any hard veering and breaking. If an obstacle appears, hold the steering wheel as tight as possible and go off the accelerator, rather than braking or steering.
• Corrugation: On gravel roads sooner or later corrugation will build up. This will result in shaking if you drive more than about 20 km/h. At a higher speed (70 km/h) it will get better, as the car skims from wave to wave, but the car will have very little grip at such speed. Any touch on the brakes and any movement of the steering wheel might give away the control of the car.
• Rutting
• River: Try to avoid water deeper than the hub of the wheel. Carefully watch other cars driving or wade through to see how deep it is. If it isn't safe to wade through then it isn't possible to drive.
  • If the engine block is hit by the water it will be cooled down very quickly, this might result in cracks. Rather switch off the engine and let it cool down to 70 or 80 degrees Celsius before crossing.
  • If the water gets into the air intake of the engine, then that's the end of the engine. It will attempt to compress water instead of air, which is not possible, and the engine block will burst. You can fit a snorkel which lifts the air intake to above the passenger compartment. Without a snorkel just turn around or wait for the water to subside.
  • Even with a cold engine and a snorkel fitted, water of a certain depth (about the height of the wheel) can be dangerous, as the air in the tyres might help lift the front of the car. This will make the car unsteerable and pull it into the river, particularly when the water is flowing.
• Sand: Release pressure from the tyres before hitting a sand track. The tyres should form large, clearly visible pockets. Depending on vehicle load and tyre type this could be as high as 2.0 bars or as low as 0.7 bars. Do not try to steer against resistance, the car will usually search his track. Do not shift gears. Do not brake as this will build up small hills of sand in front of you tyres, making it difficult to start again. If you get stuck do not try to accelerate as this will only dig you more into the sand. Try driving backwards instead. Use high ratio because the additional momentum given by the low transfer gear will cause wheel-spin.
• Mud: Try to drive as steady and as straight as possible through a patch of mud. All corrections on vehicle speed and direction will have a delayed response, be prepared for that. If you need to turn in mud, the car will first understeer (react too little), and once it got the required grip, oversteer (react too much, possibly spin). Correct slightly into the opposite direction, that is: first steer a bit more than you would on a dry surface, and once the car reacts, steer slightly in the opposite direction. Make sure you have plenty of wiper washer fluid: If you hit a hole, mud might be all over the windscreen, and you would have to wash it off quickly to regain vision of the road. Unless you are in the tundra where the mud potentially is several meters deep, you cannot sink in mud: Don't panic, and drive slowly to keep control over your vehicle.
• Sharp rocks and stones: If the track consists largely of sharp rocks, switch on the differential locks: The last thing you want is a tyre spinning close to a knife-like rock; you might slice that tyre in pieces. That also means: drive very slowly. Perhaps a bit counter-intuitively, tyres will wear fast on sharp rocks if their air pressure is high. Unless you have very old and brittle tyres (that you should replace anyway), the rubber will not take much damage if you allow it to 'flow around' sharp rocks.
• Snow

• Repair manual
• The normal assortment of spanners and screwdrivers. Hammer and pliers.
• Puncture repair kit
• Compressor - To re-inflate tires
• Plastic sheet or tarp (2x2 meter) - Vehicles break down in the worst places and weather. A sheet will protect you from sunburn, rain or sinking away in mud while effecting repairs.
• battery jump cable
• a funnel
• spark plug wrench
• chisel
• monkey wrench

• fuses
• engine oil, gearbox oil and brake fluid
• fuel filters: Especially when driving in third world countries, as the fuel is often contaminated with dirt and water
• fan belts
• spark plugs
• fuel hose
• wire
• insulation tape
• duct tape
• epoxy putty (to seal big holes in the radiator)
• self tapping screws (various sizes)- used with epoxy putty to seal holes in fuel tanks, fuels lines, brake lines etc.
• cork (larger than your oil drain plug) - situated at the lowest part of the engine the oil drain plug is a prime candidate to be ripped out by boulders in rough terrain. When this occurs the drain plug threads are normally also damaged and you will not be able to fix a replacement plug; cork and epoxy can create a very good temporary seal until you can have the problem professionally seen to.
• portable jump starter
• u-joints (driveshaft and front axle sizes)

First check the cooling water level. If it is low, refilling does not help too much, because as you have lost it during the last short period of time (you have checked it before you started your journey, haven't you?) you will probably lose it again very soon. So you have to search the leakage. Check the tubes from and to the radiator, and the radiator itself.

Bigger punctures in the radiator can be repaired with epoxy putty, smaller ones by putting egg white in the radiator. But be sure to clean this as soon as you can. If you have a leakage in the radiator hose put a (used!) chewing gum on it and fix it with some duct tape.

If the cooling water level is ok, but the engine is still running hot, something might prevent the water from being cooled. Check the fan belt, is it loose or broken? Have a look at the radiator, is grass or seeds disturbing the airflow?

A defective radiator cap may allow coolant to slowly evaporate instead of holding it in under pressure. Did you carry a spare?

Another common problem is a defective thermostat. The thermostat is responsible for by-passing the radiator as long as the engine is cold, allowing the engine to reach its optimum operation temperature quickly. But if it is broken, the cooling water will not reach the radiator and the engine heats up too much. To work around this problem without having a spare thermostat just remove it. Then the water will always flow through the radiator and your problems should be gone. Replace it soon.

Heated parts of the car might cause a wildfire.

With some practise you do not need the clutch to change gears.

• Landrover Defender
• Nissan Navara: a pickup truck
• Nissan X-Trail: Not necessarily a 4x4, there is a 2x4 type, too.
• Toyota HiLux: The workhorse for off-road driving! Very reliable and, because it is very commonly used, spare parts are even available in Timbuktu.
• Toyota Land Cruiser
• Jeep: several models

Cars by Toyota have a reputation for being very reliable (as of 2010). They are used in many third world countries, so it is easy to get spare parts almost anywhere, at least for older models.

ATVs are small 4-wheeled vehicles, usually open with a seat for one or two persons, with a cargo bed. They are used e.g. on small islands were distances are short and real roads would be unnecessarily expensive or intrusive, in national parks, where one doesn't want tarmac roads, or as an off-road vehicle where an off-road car would be unnecessarily expensive. Off-roading with an ATV can also be a sport.