Bush driving

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Thread: Bush driving

  1. #1
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    Feb 2008
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    Default Bush driving

    This is posted per request of Karistew in the post "Starting Out". Part 2 follows




    In rural Africa, the term off-road can apply to any road or track which is not a main road: In the rainy season, even major routes become four wheel drive slogs. Never trust maps -- big red lines marked as national roads are often muddy tracks: They just happen to be the major link between two areas, and the map-makers erred on the side of optimism.

    And never trust reports on road conditions by anyone other than another driver. Peasants on foot, bicycle or horse-back will honestly tell you the road ahead is "fine" or "passable" -- it is for them, but may be a nightmare for a vehicle.

    Be very careful asking directions. If you ask "is this the road to Maralal?", you will inevitably get the answer "yes". This is not malicious, but the person responding with one of the few English words they know, or else a desire to please you, the visitor. Always ask "where is the road to Maralal" or "where does this road go?"

    One of the most common phrases we heard while travelling was "the road ahead? No problem in a Land Rover." Inevitably, we would run into all sorts of problems. People in rural Africa have an abiding and often misplaced faith in the go-anywhere capabilities of Land Rovers and Land Cruisers.


    We have all seen movies of drivers charging through obstacles at top speed, which makes for good television, but is usually disastrous for the vehicle. The golden rule of off-road driving is NEVER to go faster than is absolutely necessary. SLOW AND STEADY is the motto. With few exceptions, a slow, steady approach will carry you through difficult situations more easily than charging the obstacle. And charging obstacles WILL damage your vehicle, shearing off spring shackle holders, cracking or bending your chassis, or cracking your differential casing or sump.

    Often your life will literally depend on your vehicle: Treat it with respect.

    The second rule is: Always prepare for the worst. If you are entering terrain where you would not take an ordinary vehicle, then you are likely to encounter a four wheel drive situation at any moment. If you have free-wheeling hubs, lock them as soon as you venture off road. In a vehicle with hubs, we lock them as soon as we leave the tarmac -- then if we start to lose control on gravel, a simple flick of the transfer stick into high ratio four wheel drive helps regain traction.

    Even better, use high range 4WD on gravel. Using high range four wheel drive on rough or corrugated tracks halves the fatigue loading on the rear prop shaft and half shafts by evenly spreading the transmission loads: So even if you don't need the extra traction, engage high range once you leave the tarmac.

    Always select the gear you will need for a situation before entering it, and try to stick with that gear throughout: More vehicles bog down through botched gear changes than for any other reason.

    Practice butter smooth gear changing, especially if you are driving old Land Rovers with "crash boxes" -- ie, no syncromesh on the gearbox. NEVER ride the clutch: Keep your clutch foot firmly on the floor boards, lifting it onto the clutch pedal ONLY when needed for a gear change. Even a light resting pressure can burn out your clutch plate.

    Memorize the EXACT position of all the vulnerable undercarriage points: Diffs, spring U-bolts, sump, steering rods. You must constantly be aware of obstacles which could damage these low-hanging points, and steer accordingly.

    Always walk a tricky section before driving it. Long grass can hide aardvark holes or ditches, big rocks and tree stumps. Mud holes hide an encyclopaedia of horrors. Firm sand can suddenly turn into a patch of quagmire where another vehicle has bogged down. Rivers conceal boulders big enough to stop you dead in your tracks.

    At all times off road, keep both hands firmly on the steering wheel. Never hook your thumbs over the inside of the wheel -- a sudden twist of the wheel can break your thumb. And if you have seat belts, wear them to stop yourself sliding around or cracking your head against the ceiling on bad bumps.


    The key here is to float over the top of the sand, not plough your way through. This is done by a wide tyre "footprint" and maintaining momentum.

    With standard "biscuit" tyres deflate them so that the side walls begin to bulge outward. If you have tubeless tyres, however, you run the risk of running the tyre off the rim if you deflate too far, but you can safely go down pretty far before this happens.

    Always engage four wheel drive on sandy tracks, even if you don't think it necessary. This reduces tyre wear and vehicle fatigue, improves fuel consumption and vehicle control, and is better for the environment. For most sand situations, high range will be adequate, but for really churned up sand, you will need low range.

    The hotter it is, the tougher the going through sand. As the sand heats up, moisture evaporates and the air molecules in the sand grains expand, making the surface looser and stickier, so try to drive in the early morning or late afternoon. Heavy dew or light rain helps enormously in compacting the sand.

    It is critical to maintain momentum: Carry out your gear changes before entering tricky patches. Ragged gear changing causes wheel spin, which can bog you down, or worse, snap a half-shaft.

    Never fight your steering wheel: Keep a loose grip and let the sand do the steering. If you are crossing a smooth section with no other tracks, you will have to guide the vehicle, but where other vehicles have passed, the track will do the steering for you.

    Be very careful of banks of built-up sand on the sides of tracks. If you are pulled into them, you need to maintain a firm grip on the wheel, and GENTLY, with no sudden movements, guide the vehicle back onto the main track. If you react too fast and jerk the wheels, you run the risk of rolling.

    When stopping in sand, never use your brakes, unless there is an extreme emergency, as this will bog you down -- let the sand slow your momentum. Once stopped, clear away the ridges of sand which build up in front of your tyres and first reverse a short distance back along your tracks before restarting.


    Sand dune driving should never be done for the fun of it: It is environmentally destructive and dangerous. But there are times when sand dune cresting is the only route through. Always do a walking check of the dune -- some gentle dunes can conceal a rocky cliff on the far side.

    Approach dunes straight on, at right angles, and never at an oblique angle which could result in rolling. Build up enough momentum to just get you to the top of the dune, at which point you need to halt the vehicle with it literally stuck on the hump, with the nose pointing over to the other side. You then dig away the crest, dropping the nose, and descend SLOWLY, in low range first or second gear, depending on the steepness, with feet firmly on the floor boards to avoid touching the brake or accelerator pedals: Let the gears do the work, the brakes could lock and lead to your rolling. Your descent must be dead straight -- if you head down at an angle, you will probably roll.


    Corrugated gravel roads are the most common road surfaces in Africa. In extreme cases, like the main A1 "highway" linking Kenya and Ethiopia, these corrugations take on the proportions of a malevolent beast designed to destroy your chassis, suspension and nerves.

    Corrugations are hard ridges of compacted gravel or stone which develop with repeated road use -- the softer sand blows away or is compacted, leaving behind an endless series of regular, parallel ridges.

    There are three basic approaches to driving on corrugations: Very fast, very slow, and driving on the wrong side of the road. All three work to a degree, and on a long corrugated road, you would probably combine all three.

    We add a fourth technique, which is a matter of personal choice: We lower our tyre pressures until the tyres start to bulge. This acts as an extra set of shock absorbers, and punctures are much cheaper to fix than a cracked chassis or broken spring. This also vastly improves passenger comfort.

    Then it's pretty much a matter of choice: Driving fast gets you to a speed where you leap from one corrugation to the next, dancing over the top of the bumps. You need to be a very confident driver -- you have very little control over the vehicle in an emergency, and the slightest mistake can end in a disastrous skid.

    Going slowly means you are driving through each dip and over each hump, and is far kinder on your vehicle and your nerves, but vastly increases travelling time.

    If there is little traffic, try driving on the wrong side of the road: This way, you approach the corrugations from a side which usually has some windblown sand filling in the worst of the ridges.

    Keep your eyes on the road well ahead, and not immediately in front of your wheels. Your brain will soon learn to record a series of snapshot images, giving you better anticipation and better reaction time. Always be alert for any change in the colour of the road -- a darker or lighter patch or a different colour always signals a change in the surface.

    If you hit a dip or washaway, apply steady, but not heavy, brake pressure. Just before hitting the dip, accelerate slightly. This drops the weight of the vehicle onto the rear axle and decompresses the front suspension, making the impact much more gentle.

    ALWAYS DRIVE WITH HEADLIGHTS ON ON GRAVEL ROADS. Pull over if you see a big truck approaching, as they tend to drive very fast in the middle of the road, scattering showers of small stones. If stuck behind a big truck on a dusty road, never overtake unless you have a wide section of road, and are sure there is no oncoming traffic. Rather pull over and have a cup of tea and let the truck get ahead of you.

    Make sure your load is well secured -- bad corrugations can trash careful packing, reducing food supplies to a sticky mess. Stop regularly and check your wheel nuts: They work loose on corrugations. And change drivers every two hours, as corrugated roads require a high level of concentration.


    Driving on very rocky tracks is really just common sense: Avoid the big rocks, drive slowly, and engage high ratio four wheel drive to reduce transmission wear and give greater vehicle control. We always drop our tyre pressures to the point where the tyre is just beginning to bulge. This makes the ride a lot more comfortable, saves on suspension, and saves on punctures, as the tyre has some "give" in it when it hits rocks, rather than presenting a rigid, hard surface which can split.

    In deep, V-shaped gullies, be careful not to drop one side of the vehicle into the deepest point: Drive with the wheels straddling the gully so as not to end up hopelessly jammed in a position where digging and pushing do not help. When approaching a small gully head-on, enter at an oblique angle, dropping one wheel at a time into the gully, and ensure the first wheel is already exiting the gully when the second one drops in.


    Heavily used tracks -- especially dried out mud tracks -- are often deeply rutted, to the point where it is impossible to drive in the ruts without catching the undercarriage on the "middel-mannetjie".

    This is made far worse when the road has been used by heavy trucks with a wider axle length than standard pick-ups.

    Here you must drive with one wheel in a rut, and the other on the hump, to prevent your undercarriage getting hung up. If there is enough side room, it is often possible to drive with one wheel on the middle hump, and one on the far side of one of the ruts, effectively turning the track into a V-shaped gully.

    But there is one major problem when driving like this: With a heavily-laden, top-heavy vehicle, it is easy to reach critical lean angle and for the vehicle to capsize. This situation calls for steel nerves and a fine sense of judgement. If the ruts are very deep, you may have to dig away sections of the middle hump to lower your centre of gravity.

    We carry several empty plastic maize meal sacks, available on any market in Africa. In a critical lean situation, we tie several of these sacks onto the danger side of the vehicle, then fill them with sand. This extra ballast can make the difference between safe passage and a disaster. This is particularly necessary if you are on a mountain track with big drop-offs, as we encountered in Kenya’s Aberdare Mountains and Mau Forest, and in several places in Ethiopia, Malawi and Uganda.


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  3. #2
    Join Date
    Feb 2008
    Cape Town
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    Here's part two:


    Story: Tony Weaver and Liz Fish
    Photographs: Tony Weaver

    TEXT: 2 002 words

    LAST month we covered the easy side of off-roading -- dry track driving. This month it's the real tough stuff, mud and snow driving, guaranteed to reduce the toughest of macho adventurers to tears sooner or later.


    Mud is one of the trickiest mediums to master and it's mostly a matter of creative improvisation. But learning a few basic rules can make life easier.

    If you hit a bad hole you know you cannot get through (common on roads used by heavy trucks), dig drainage canals to lead the worst water out of the hole, sit back and brew a cup of tea. This may be enough to get you through. If not, wait for the next big truck and negotiate a tow. This may cost a few bob, but it's better than spending the night in the mud hole. If the hour is late, look for a camp site well clear of the road and try again in the morning.

    It's at times like this that a rooftop tent is worth its weight in good red wine.


    Make sure you know the exact position your steering wheel is in when the wheels are pointed dead ahead: It is easy to turn your wheels too far to one side without realizing it, as the vehicle continues going in a straight line, getting more bogged by the second. If necessary, mark this steering wheel position with tape or koki at the top dead centre position.

    Before entering a deep hole, protect your engine by dropping a canvas sheet across the front. This deflects water from the engine, lessening the chance of drowning the motor. For petrol engines, keep a can of Q-20 or other dispersant handy to spray on electrics.

    Reducing tyre pressure helps increase traction, as does clearing clogged tyre treads with a screwdriver.

    Areas with large herds of wild animals pose particular hazards: A pod of hippo, or a herd of buffalo or elephant walking through a mud hole wreaks havoc: Check the bottom meticulously for deep spoor hidden below the water surface.

    If the hole is very deep, unpack recovery equipment like spades or Hi-lift jacks before entering the hole -- you may not be able to open doors once bogged down deeply.

    Mud driving is not a democratic exercise: If there are more than two of you, designate a driver and one navigator: The navigator is the boss. The rest of the passengers follow on foot so they can't heckle the driver, ready to dive in and push the second the vehicle starts bogging. Get democratic again when you are hopelessly stuck.

    The driver and navigator must walk the stretch of mud together, assessing potential dangers and routes. Fill deep holes with rocks or other material. Check for alternative routes -- what looks like dense bush may be navigable with a bit of creative driving. All water-filled holes MUST be waded through to establish their depth and hidden hazards, like rocks and tree stumps. Then map your route through the mud hole, using sticks jammed into the mud to indicate drop-offs and other hazards.


    The navigator must stand in a clearly visible position ahead of the vehicle, out of the mud hole, and use clear, pre-arranged hand signals to guide the driver through. The only hand signals you need to rehearse are go left, go right, stop, go and reverse. The driver must watch the navigator, not the road.

    Use very small hand movements to guide the driver: No matter how hairy the situation may look, it is crucial the navigator doesn't use exaggerated arm movements which can panic the driver.

    Select your driving gear, and try not to change gear throughout the crossing -- maintaining momentum is critical, but there is a very fine line between going too slowly and going dangerously fast. Low range second or third gear are your obvious choices, avoiding wheel spin. First gear, low range, gives too much torque and leads to wheel spin. If you have a big, powerful engine, opt for low range, third or fourth gear.

    Don't let your accelerator foot slip and cause a sudden power surge. Reduce power on slippery bits, and gently feed in power as soon as traction improves. If the wheels spin, gently drop the revs until they grip again.

    If you start bogging down, stop immediately without braking, keeping the engine running. Get out and plot the best course of action -- usually this will be simply reversing or minor digging, whereas if you rev the engine and try to force your way out, you may be up to your axles in goo in seconds.

    If you start to skid, steer INTO the skid, not away from it, keep your revs up, and NEVER use your brakes. Jiggling the steering from side to side helps the wheels regain traction, but avoid exaggerated steering.

    Diff lock, if fitted, will help with bad mud traps.


    In rural Africa, you may be doddling along a surfaced road which suddenly turns into a skid pan when you hit wet clay or mica soil. It is a horrible sensation -- the back end swings out uncontrollably, or you simply start sliding with no traction whatsoever.

    Stop gently, then dig short guide trenches for the wheels, cutting away the top layer of particularly slippery mud. This gives enough traction to get back onto the main road surface. On one nasty descent in Ethiopia, we had to trench over a hundred metres of road after spinning off the road through 540 degrees -- at 15km/h!.


    Steep, muddy uphills will usually not have deep pools of standing water and mud, but are likely to be very slippery. Here you have to rely on momentum, so a reasonably high speed is necessary to get over the hump -- make sure you know what is over the hill, out of sight.

    Steep downhills are worse: If they are very steep and dangerous, it may be safest to winch yourself down. If you have no winch, proceed very slowly, in second gear, low range. First gear will cause a sliding descent where the engine can't catch up to the vehicle speed. DO NOT touch the brakes -- use the engine to retard skidding. If you start to skid, accelerate very gently. If you have wheel chains, fit them to the rear wheels. Again, digging shallow trenches for the wheels can improve traction enormously.

    Small streams running down the sides of hills often have gravel bottoms, offering good traction for two side wheels.


    Cotton mud is a particularly nasty type of black mud found throughout Africa, and poses a very different challenge to ordinary mud. Cotton soil when dry forms a rock hard, black surface which is punishing on tyres and suspension, but poses no threat of bogging you down.

    But after a few days of rain, cotton soil sucks up water like a sponge, becoming a thick, glutinous, impassable bog.

    There is only one solution to cotton mud -- avoid it. It is often possible to detour by making a new track through the bush, but you then run the risk of bogging down off the main road. If you have no option but to go through, the best option is to rush it at speed, risking vehicle damage. Rather set up camp and wait a few days for other options to open up. Or retrace your steps and find an alternative route.

    There is very rough cotton soil in the Western Corridor of the Serengeti, on side tracks in the Maasai Mara and Amboselli game parks in Kenya, on unpaved roads in Ethiopia, and on the main A2 "highway" north from Isiolo in Kenya to the Ethiopian border at Moyale. The "dry season" route into Lalibela in Ethiopia has dangerous sections of cotton -- if you go in in the wet, take the rocky back route via Kobo, a hair-raising, exhilarating roller-coaster of a track.


    On Sahara maps, these are usually marked as "Sebkha", "Sebkhet" or "Chott". On southern African and East African maps, as "pans".

    This is nasty mud which regularly swallows entire. The seemingly hard, white surface of pans like Sowa and Makgadikgadi in Botswana conceal treacherous bogs. This is the one type of mud where wide tyres work. Deflate narrow tyres to sand pressures.

    We are loath to give advice on salt pan driving because that encourages offroad vandalism. But remote expeditions often have no option but to go forward, so use common sense and follow a few basic rules:

    Never park on the pan while inspecting the surface -- a moist pan is like a giant creme brulee: Solid on the surface, pure mush underneath. A really healthy pan can swallow a vehicle in minutes.

    Walk the route. If you start sinking in, don't even think of driving. If the surface feels firm, dig a hole about half a metre deep: If you find dry ground all the way, then it may be safe to proceed. Drive fairly slowly in low range third or fourth -- if you rush it, you may find yourself too far in to get out again. Always stick close to the edges of the pan and near to, but not on, existing vehicle tracks.

    If you do start bogging, immediately stop (gently) and reverse out on your tracks.


    Drying mud cakes itself into a hard, heavy, destructive mass hanging on hydraulic lines, fuel pipes and electrical cables, clogs up universal joints and adds unnecessary weight. Thoroughly clean the entire vehicle after muddy travel. If you are miles from civilization, you can clean off a fair amount of mud by driving through as many puddles as possible.

    Don't park in a stream and wash off, as many overlanders do: All the grease and oil on your undercarriage will wash down into a village water supply.

    You must re-grease your vehicle after every trip through mud (and sand). Universal joints/CV joints in particular must be well greased, or else you will go through a set every couple of months.


    Yes, in Africa: Lesotho is notorious for it -- the Sani Pass has patches of ice which never melt -- and we got caught in very heavy snow in Ethiopia's Bale Mountains.

    Slow speeds in high range four, very careful driving and meticulous vehicle control are essential. Tyres play a very important role in snow, and the deeper and chunkier your treads, the better. Decreasing tyre pressure by a third improves traction. Wide tyres are dangerous, as they float over the top. Wheel chains are an enormous help if you have them -- but they place an enormous strain on the drive train, and rip up the surface of tracks.

    Avoid wheel spin, and always brake very gently, as front wheels lock with frightening speed on icy surfaces -- use gear changes or short, gentle taps on the brake to slow down. When travelling in convoy, keep a big gap between vehicles.

    When camping overnight, leave the hand brake off -- brake drums can freeze solid. If you leave the vehicle for a few days, pack cardboard or branches under tyres to stop them freezing to the ground. Lift windshield wipers, loosen fan and drive belts, and try to fill all fuel tanks to the top to limit condensation. Cover the engine with a blanket or canvas sheet to stop components freezing, and to keep out wind-blown snow.

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