Kedah 4x4

Hills should always be tackled straight up or down and sideway slopes avoided like the plague. A vehicle has to be at an extreme angle for it to roll head to tail, whereas a sideways roll can occur at much more modest angles. The way your luggage is packed has a pronounced affect on the angle a vehicle will roll sideways. You should avoid placing containers of extra fuel and water on the roof of your vehicle, as this will significantly decrease the angle at which a rollover is possible. This occurs because the extra weight on the top of a vehicle increases the 'center of gravity'. Heavy gear should always be packed low inside the vehicle and as centered as possible while only lightweight gear should be placed on roof racks.

The type of terrain will also affect the sideways rollover angle. In sand, mud or other soft terrain the weight transfer to the downhill wheels will cause them to sink, increasing the actual slope angle. So what may appear an acceptable angle on firm terrain may result in a rollover on soft terrain.

This type of terrain is one where vehicle type is very important. Ground clearance and suspension travel are two of the main criteria. High ground clearance allows the larger rocks to pass underneath without contacting vulnerable vehicle parts while good suspension travel allows the wheels to remain in contact with the ground.

Independent suspension usually provides a smoother ride in this type of terrain, but its design limits the wheel travel and ground clearance available. It goes without saying that rocky ground should be attempted at low speeds to minimize vehicle contact with the terrain.

While independent front suspension generally provides a smoother ride, it has a variable ground clearance to the front diff. As the front wheels hit a bump, the wheels rise up to absorb the bump. However the diff remains in the same relative position, effectively reducing the ground clearance under the diff. This can result in the diff hitting the ground, even though the obstacle under the diff was only half the height of the static ground clearance.

Live axle front suspension generally does not provide as smooth a ride as independent front suspension. However many live axle suspensions are now fitted with coils rather than leaf suspension, which significantly improves ride comfort. The advantage of live axles when off road is that when the wheels hit a bump, the whole axle rises with the wheels to absorb the bump. This maintains the same clearance from the diff to the ground.

While this is an advantage off-road, the fact the weight of the entire axle and diff is constantly moving with any bumps leads to a rougher ride, compared to independent front suspension.

When large drop-offs or ledges are encountered, they can be tackled at an angle to allow one wheel at a time to mount the obstacle. Bear in mind how this will affect the position of the vehicle as turning at an angle to a down hill ledge may result in the side rollover angle being reached.

Traveling on long straight stretches of gravel roads can lull the driver into a false sense of security. Modern 4WD's can make a relatively rough road seem smooth with their long travel suspension and sound deadened interiors. Speed creep can occur in these circumstances and when a bend is encountered the high center of gravity in most 4WD's may cause you to cross to the other side of the road or it can lead to a high risk of rollover.

If a sudden obstacle e.g. a kangaroo, appears it is very important not to swerve while braking. This goes for any road surface and not just gravel roads. However it is more critical on gravel roads as once a skid or slide starts, it is very difficult, if not impossible, to regain control. There are exceptions to this rule such as a truck heading straight for you at high speed. It is better to avoid a collision with the truck and take your chances hitting a roadside object than to have a head-on collision. However, neither of these options are particularly attractive and it is for better to be traveling at a safe speed for the conditions.

In part-time 4WD's it is best to use 4WD on gravel roads to gain the better traction and road-handling of 4WD. Gravel roads provide enough slip not to cause any transmission windup problems. It is not necessary to use the center diff lock of permanent 4WD's on gravel roads. Corrugated gravel roads can cause severe vibrations that can cause vehicle damage as nuts rattle off and vibrations damage electrical components. It is quite common for glass food containers to shatter even when stored in eskies. The key to minimize these problems is to find the right combination of vehicle speed and tire pressures.

Increasing vehicle speed until it 'planes' over the corrugations can reduce vibration significantly, but the planing speed may be too high for the driving conditions. Depending on the corrugations, planing speed is around 60-80 km/h. Lowering tire pressures reduces vibration as the tire sidewalls act as shock absorbers. However this causes the tire to heat up and can lower tire life or even cause tire failure. It is sometimes better to sacrifice tire life and lower tire pressure to reduce the damage being caused to the vehicle, as well as the comfort of the vehicle’s occupants.

After driving long distances on poor quality roads, it is a good idea to check all nuts and bolts to see they haven't vibrated loose. It is especially important to check all suspension components. The easiest way is to use an adjustable and when a loose nut or bolt is found, use the proper size wrench or socket to tighten it rather than risk rounding the head.

Driving through mud is a cross between ice skating and walking through quicksand. Some types of mud have a greasy top layer with a hard baked surface underneath, while other types can be a bottomless quagmire of gooey mush.

Different types of mud require different driving techniques and equipment. Greasy mud with a hard bottom layer is best suited to narrow tires to allow them to cut through the top layer to bite the hard surface below. Wide tires in this situation tend to float on the greasy top layer without reaching the hard surface underneath.

Thick gooey mud tends to favor wide tires as they give some flotation, similar to wide tires favoring sand driving. Lowering your tire pressures can help just like when sand driving, though its best not to lower tire pressures below 20-25psi for mud.

Regardless of what type of mud and what width tires are fitted, the tread pattern needs to have large lugs to allow the tire to 'clean' itself. If they don't, the lugs fill with mud and the tire becomes a 'slick' with little chance of getting traction. Road orientated tread patterns tend to have closely spaced lugs to put more rubber on the road and to reduce tire noise at highway speeds. When it comes to mud, road tread tires are at a significant disadvantage, whereas in sand they help avoid 'digging in'. Dedicated mud tires have large open spaced lugs to keep the tire clean. However, they handle worse on bitumen as there is less rubber in contact with the ground and in sand they tend to dig in. Also they can have an annoying drone at highway speeds.

Mud Driving Techniques

Unlike some other types of terrain, mud-driving techniques vary on the type of mud. Reducing tire pressures can help in 'bottomless' mud whereas it can make things worse when a hard surface is below the mud. Mud usually tends to hide obstacles such as tree roots and sticks just waiting to slash your sidewalls, so its best to avoid reducing tire pressures if you can avoid it..

Driving on the peaks between tire tracks can provide firmer ground, as water tends to collect in the wheel tracks. Though sometimes the existing wheel tracks have cut through to the firmer surface underneath and provide the best traction.

Moving the steering wheel left to right about 90ฐ from the center can help the front wheels bite into the mud in search of traction. Do not turn the wheel too for as you can end up making things worse.

As you have probably gathered by now, mud driving is unpredictable and you need to have a knowledge of different driving techniques to know which one to apply in each situation. What doesn't change is the need to have good mud tires with big self-cleaning lugs and good recovery equipment.

Tire Chains

A way to overcome the cost and audible discomfort of mud tires is to use tire chains on your existing tires. They will dramatically improve your traction, but they do damage the track surface. It is best if they are only used when you HAVE to traverse a muddy track, as they can make it almost impassable when it dries out. If possible, it is best to let a muddy track partially dry out so you can get through in 4WD without using chains, as chains will deteriorate the track for future users.

There are two main types of tire chains, the bar (ladder) pattern or the diamond pattern. The bar pattern is better for mud as it really bites into the surface, whereas the diamond pattern is normally used for snow driving. It provides a smoother ride as the chain is in constant contact with the surface and has side-slip resistance, whereas the bar type has more of a digging action. Both types of chains can be used in either situation so if you do purchase them, choose the sort for your main type of driving.

Maintenance
Mud, especially clay and thick mud, tends to stick wherever it touches, It can build up under the wheel arches to the point it acts as a brake on the tires. This type of build-up is obvious and has to be cleared immediately, but other types of build-up that are not so obvious but still need immediate removal is on the rims. Even a small amount can throw your wheel balance out dramatically and can lead to uneven tire wear and a vibrating steering wheel.

Once all visible mud has been removed, its necessary to check items like diff and gearbox breathers to ensure they are clear, otherwise it can lead to seal damage in the long term. Also check all drain holes on the chassis etc to ensure they are not blocked. Its surprising how mud can even find it’s way to block drain holes on the bottom of doors!

The fundamental theme with sand driving is to conserve your momentum. Since traction is at a premium, any increase in speed can be difficult, if not impossible, and you do not want to lose any momentum, as you may not be able to regain it.

Tire Pressures

The first thing to do before driving on sand is to lower your tire pressures. This is done to provide better flotation by increasing the size of your "footprint" and thus dramatically improving your traction. It also reduces the amount of strain on your vehicle and minimizes wear and tear on the tracks.

The optimum tire pressure depends on your vehicle, the type of tires fitted and the terrain. The following technique provides a good starting point to find the optimum pressure and is best performed before leaving the bitumen.

Park your loaded vehicle on a level surface and place a brick 1 cm away from the sidewall of your rear tire. Deflate that tire until the sidewall just touches the brick and then measure the tire pressure. Use this pressure as your starting point when initially lowering your tire pressure for sand driving. As you become more familiar with sand driving, you can alter this pressure as the terrain dictates.

If you haven't performed the above technique before you reach the sand, don't fret. A good rule of thumb is to use a pressure of 15 psi.

Remember though, if you are going to lower your tire pressures, ensure you have a pressure gauge and some means of pumping your tires back up.

As you lower tire pressure, the tire becomes more vulnerable to damage by stoking the sidewall or rolling the tire off the rim. The lower the pressure, the higher the risk. However the gain in traction can be remarkable and may make the difference between becoming hopelessly bogged or simply driving away. The "correct" tire pressure becomes a decision between better traction versus increased risk of tire damage.

In severe cases of bogging, tire pressure can be lowered to a minimum of 40 kPa (6psi), as most tires require at least 6psi to remain seated on the rim while stationary. In almost all situations 10psi should be used as the minimum pressure as 6psi is likely to result in tire damage i.e. tires rolled off rims or punctured sidewalls. Speeds should be severely restricted at these low pressures. To minimize tire damage, it is important that these low pressures are only used on sand and tire pressures should be increased if limestone or rocky outcrops are encountered, or when the terrain becomes more firm. Failure to do so will almost certainly result in tire or rim damage.

Sand Driving Techniques

When traveling on sand, you should endeavor to follow in the tire tracks of the vehicle in front as they have already compressed the sand to form a firmer surface than un-traversed ground. Never drive on vegetation as this will destroy it and lead to erosion and environmental damage.

You should avoid rapid changes in speed when accelerating or braking. Braking on sand will cause a mound to build up in front of all wheels and possibly prevent your vehicle from taking off. Rapid acceleration simply digs the wheels in and can actually lead to slower take-off speeds.

Take-off should be performed as smoothly as possible with gear changes done at fairly high revs. Sand driving requires plenty of engine power to get your vehicle "planing" on the sand. It is advisable to use low range as this multiplies the amount of engine torque available and will provide that extra gear if you encounter a particularly soft patch of sand. Check that your tires are pointing straight ahead when taking off to reduce the takeoff effort required.

When stopping on sand, depress the clutch and allow the vehicle to coast to a stop. This will minimize any sand build-up in front of the wheels. If the terrain permits, coast to a stop, rather than braking, with the vehicle pointing downhill as this will aid take-off. Avoid the soft sand at the base of most dunes and gullies when stopping.

When turning, make the turn as wide as possible to reduce the chance of bogging. Your front wheels act more like a rudder in sand and turning too sharp has a similar effect to applying the brakes.

Steep sand dunes can be traversed only straight up or down. If you drive even on a slight angle, the weight transfer is to the downhill side wheels. If the vehicle starts to slip, the downhill wheels tend to dig in and make the angle of the dune even worse, leading to a potential rollover.

If you are traveling straight down a steep dune and the back end starts to slip sideways, it is best to accelerate slightly to try and straighten the vehicle. Never use the brake, as this will cause weight transfer to the front wheels and can increase the back end movement.

If traveling up a dune and you do not get to the top, reverse down the dune in gear, NEVER coast down the dune and NEVER attempt a U turn.

When you return home after a beach trip, it is important to hose down your vehicle to remove all traces of sand and salt. Pay special attention to areas like the mudguards where sand is sprayed around and tends to get trapped. Thoroughly hose underneath your vehicle as well, as there are many nooks and crannies where sand can also get trapped.

Vehicle Recovery in Sand

As soon as you become bogged, avoid the temptation to simply floor the accelerator as this will just make vehicle recovery more difficult. Put the vehicle in reverse and gently try to back along your tracks as they provide a compacted path. When you have reversed a sufficient distance, try going forward again while being careful not dig yourself in. Hopefully you will travel further each time you repeat this technique and eventually be able to slowly pass through a particularly soft section.

If you cannot reverse out of trouble, get out of the vehicle and let your tires down further. A rule of thumb is to drop them by a further 12 psi. Before trying to reverse out, remove the build-up of sand from behind the tires. See if any part of the underside is touching. If it is, clear the sand away to allow the vehicle to reverse out. You may need to try this several times.

If necessary, continue to drop the tire pressures to 10 psi. Also, never underestimate the assistance of your passengers giving a push. As mentioned earlier, tires can be lowered to 6psi in extreme cases, but this should be avoided if other means of vehicle recovery are available.

If you are still stuck and your tires are down to the minimum pressure, you will have to resort to a snatch strap, winching or jacking to extricate yourself. The easiest method is usually by snatch strap, but this relies on another vehicle being present. If you are by yourself you will have to resort to winching (if you have one!) or jacking.

Summary-Sand Driving

· lower tire pressures to greatly improve traction and reduce track erosion

· drive smoothly with gear changes at high revs

· ensure wheels are pointing straight ahead when taking off

· avoid the soft sand at the base of dunes and gullies

· make turns as wide as possible

· ONLY travel straight up or down dunes

· follow in others tire tracks to drive on compressed ground

· avoid braking by coasting to a stop

· do not floor the accelerator if you are bogging down

· when bogged, try to reverse on your own tracks

thoroughly hose down your vehicle after a beach trip

When driving on dusty roads, its a good idea to have all your windows closed and the ventilation control set to outside air with the fan on high. This pressurizes the vehicle interior slightly and helps reduce the amount of dust sucked into the vehicle. When another vehicle approaches, move the ventilation control to "recirculate" to stop dusty air coming in. Remember to move the ventilation back to outside air once you have passed through its dust trail or else the pressurization effect will be lost. In hot weather, vehicles without air-conditioning have to make a choice between minimizing dust intake or winding the windows down for the (cough) fresh air.

The biggest problem area for dust intake is from the rear tailgate. Check that the rubber seals are in good condition and that they seal when closed.

Don’t be fooled into thinking that experienced off-roaders don’t get stuck - they get stuck more than anyone! This is because they are keen to try the impossible, are not afraid of ridicule nor are they unfamiliar with the processes of getting a vehicle unstuck. It is important to realise that there is no shame in getting a vehicle stuck.

The most important tool required to free a vehicle from a sticky predicament is common sense. I have lost count of the number of times I have come across a bogged vehicle where the driver has taken out his winch or snatch strap without thinking through the problem. Three minutes with a well used spade and a gentle right foot and the vehicle is free. Common sense and a methodical approach often results in little work and a seemingly miraculous escape for the vehicle concerned.

This chapter covers the vast array of recovery equipment available and is followed by tips on using the equipment and a common sense approach to getting unstuck.

Vehicle recovery equipment makes up a large proportion of a typical off-road load. The following is a list of equipment that the serious off-roader should carry to free a vehicle or to get it over an obstacle where normal driving has failed: