4×4 Vehicles

If you are thinking of heading off to an off-road experience, then you should first take into consideration what part of your vehicle you always need to consider the parts which are most vulnerable to damage. Usually during off-road trips, the part that is most vulnerable to damage is the undercarriage. Though some vehicles have solid axles in the front and back, this is still not an assurance that the can offer 100% protection. Even with solid axles, your undercarriage is still prone to damage when taken to an of road trail.

Most of the vehicle manufacturers these days underestimate the tracks where their vehicles will be used; as a result they only offer standard protection plates which are oftentimes too thin. The sad part is that these standard protection plates are not able to protect a 2 ton vehicle from rocks or debris that are common in off-road trails.
Usually a single rock that hits a standard and weak protection plate will damage your vehicles in a lot of way. Damage to your plate can dent your sump which can also damage the intake of oil and ultimately lead to a disastrous engine failure. There are also instances when standard protection plates leave the radiators and intercoolers exposed thus becoming very vulnerable to damage. The same goes with the sensitive diff actuation components that can be found on IFS vehicles.

Luckily, there are still some companies which have given importance to this matter and considered this as a serious problem which needs to be addressed. As an answer to this dilemma, they have come up with products that are meant to effectively protect the undercarriage of our vehicles. Great examples of these products are the plates that range from R1500 to R2500. Investing on these sturdy protection plates will save you money from having your vehicles repaired from damage to the undercarriage. This can be considered as one of the most important, if not the most important, modification you can do to your vehicle. Even if you are low in budget, to the very least have an aftermarket sump guard fitted to your vehicle.

There are quite a lot of sump guards, or bash plates as they are fondly called, being offered by different manufacturers. Among these manufacturers, the most highly recommended are those that are made by For-Fours. You can visit their website at www.for-fours.com for more information on their products.
Whichever manufacturer you intend to buy these sump guards from, there is a general rule as to what to look for in a good quality protection plate. The first consideration is that it should be made of 3-5mm of mild or stainless steel. If you want to go for aluminum, choose one that is at least made of 8mm aluminum. The bolts should also be protected from damage and it should be secured to the vehicle so as to provide solid support to the weight of the vehicle.

Second consideration is the type of vehicle to be used. An IFS vehicle should have a plate that can protect the engine sump, front differential, radiators, inter cooler and oil cooler from any form of damage. Whereas an SFA vehicle will only need a plate that can protect its engine as well as the front differentials and keep it away from the engine.

Third consideration is the designs and the look of the plate itself. It has to have a sufficient space between the plate and vehicle so that in cases where there is impact, it will still have room to bend as oppose to immediately damaging the vehicle parts itself. This extra space will also allow for sufficient airflow to the radiator and other coolers. It is also a good idea to spend more money on corrosion proof plates, that way you can be ensured that your plates will not rust. It should also have an access panel for easy removable during oil change.

OBSTACLE: WATER CROSSING

Vehicles and water generally do not make the best of companions and the simple rule of thumb with water is to avoid it. If a water crossing is unavoidable, it must be approached with some diligence especially if it is fast flowing.

Check for:

Depth of the water – The easiest method is to stand next to one of your tyres and use the top of the wheel rim as a depth reference. When you go through the water, you must ensure that it does not exceed this reference point.

Obstructions – It is important to check each wheel track, so walk the one out and the other one back. Use a stick to check the area between the tracks for any unseen obstructions.

Firmness of the bed – Particularly when doing river crossings understanding the amount of traction available during the crossing is critical. Use the stick to probe the ground to ensure it is firm enough to hold the weight of the vehicle and provide traction.

Strength of the current – The side of the vehicle presents a large area of resistance to flowing water. As the water pushes against the side of the vehicle, it builds up pressure. The water will initially flow around the vehicle but if the flow is strong enough the water pressure can actually begin to lift the vehicle, just like the bow of a boat, and this may cause the vehicle to lose traction and start being pushed sideways by the water leaving the occupants in danger of being washed away.

Do not wear a seatbelt in deep water – In the event of a vehicle being washed off a bridge or down a river, the vehicle can often roll or be engulfed by water quite rapidly and it is for this reason that not wearing a seatbelt while crossing a river is the recommended practice. Once through the water the seatbelt should be fastened again.

Know the manufacturers maximum wading depth – Not all manufacturers list the wading depth of their vehicles but the owner’s manual should be consulted to get an indication of maximum wading depth. Failing this, the driver should take note of where the vehicles air intake is situated and what moving parts may be exposed to water when crossing. The general rule of thumb is not to go deeper than the top of the wheel rim if a depth has not been specified in the owner’s manual.

Use 2nd or 1st gear depending on the terrain – Use 2nd gear when the base is firm and 1st gear if it is rocky. The key is to balance the ability to maintain momentum during the water crossing against the grip available. Also take careful note of the exit from the water and how it will be affected by the water previous vehicles as well as your vehicle will carry onto it, many times the exit will become slipperier with the passing of each vehicle.

Create a bow wave – Creating a bow wave is a key principle of water crossings. The idea is to use the front of your vehicle to push the water in much the same way as a boats bow does. The forward momentum of the vehicle creates a high-pressure zone and the water rather runs around the car than go through it. The added benefit is that as the water moves around the front of the car it create an area of low pressure usually around the front wheels which helps to draw water away from the front of the vehicle. The speed of entry into the water is a critical for a successful water crossing. Too slow and you will not create a bow wave, too fast and there is a very real chance that you can push your engine fan back into the radiator or at the very least break off a blade on the fan which will lead to engine cooling issues.

Avoid stalling if the exhaust is under water – If stalled do not restart unless you are sure the exhaust is above the water. The main reason we avoid restarting in water is to insure there is no possibility of any water being ingested by the motor.

Rather safe than sorry. Diesel engines work on compression and they are easily damaged when water infiltrates the fuel/air mixture in the combustion chamber chase the designed component strength thresholds to be exceeded.

Check differential and gearbox for breathers – When going through water the sudden cooling effect on the working parts can cause them to contract or ingest water. In the case of the engine, gearbox and differentials these all contain oils or lubricants that when exposed to water lose their lubricating characteristics and may even discolour to a milky appearance. Whenever a vehicle has been through water it is always best practice to have the oils in the engine, gearbox and differentials checked to ensure they are in good working order. If you intend to go on a trip, where river crossings are a regular occurrence the fitment of breather pipes to the gearbox and differentials are advised. These pipes ensure that when the constriction occurs air is drawn in from a position above the waterline.

Use the diff lock in muddy conditions – Whenever the surface the tyres will utilize for grip has obscured visibility it is advisable to engage the diff lock or vehicle traction aids. Rather give the vehicle its best chance of a successful crossing on the first attempt.

Dry your brakes with left foot braking on exiting – As with the differentials the brakes experience cooling when going through water and this compromises their braking ability. This can be further hampered by the mud and other particles carried by the river getting between the brake components. By simply lightly resting your left foot on the brake after exiting the water the contact surfaces of the brakes are cleaned and reheated to operating temperature.

Close windows and put the fan on full blast – Water flows towards the point of least resistance so by simply closing the windows and putting the interior fan on full blast the resultant increase in cabin air pressure reduces the likelihood of water entering the cabin. It is important to note that the air conditioner should be put off prior to entering the water as it is generally mounted quite low on an engine and is likely to be exposed to water during crossing and hence excessive wear. In addition, the recirculate button should also not be engaged. The idea is to introduce outside air into the vehicle cabin and not recirculate the air already contained inside the vehicle.

If you want more details on the vehicle manufacturer affiliated off-road training programs we are involved with drop an e-mail to ralph@4x4training.co.za and I will gladly provide the details on how you could register for complementary off-road driver training.

In the late 1990’s and early 2000’s several accidents involving Ford Explorers fitted with Firestone tyres were reported leading to the Ford Motor company in the USA in conjunction with Firestone facing a major legal action as a result of tyre failures and the consequent rollovers that took place. These events conspired to both tarnish the perception that a larger vehicle naturally provides more protection for it occupants as well as the apparent lack of passive safety equipment fitted to SUVs.

What made these events even more noteworthy for the off-road community was that most of these incidents happened on a tarred surface where optimal ride and handling conditions presented themselves.

South Africa too has had its fair share of controversy with regard to SUV safety which has ultimately led to a greater inclusion of safety features as standard on most off-road vehicles.

Technology such as Anti-lock braking (ABS), Electronic brake force distribution (EBD) and airbags are some of the features the general public now expects as standard fitment. But even these technologies while providing life saving performances on a tarred surface can be found wanting off-road. Anti Lock braking for instance works on a principle of measuring comparative wheel rotation under braking, the amount of force being exerted on the brake pedal as well as steering input, based on the data collected the amount of brake pressure is varied to each wheel and the wheel is prevented from entering a brake lock up state, i.e. the brake callipers grip and release hundreds of times every second ensuring braking forces without wheel lock up.

The ABS system also monitors the amount of resistance the road surface is providing the tyre in order for it to brake the vehicle. This is ratio is referred to as the co-efficient of grip and is basically the tyres ability to grip the surface or provide traction. When the co-efficient is exceeded the tyre will skid or not be able to maintain directional stability. This is particularly important when breaking through standing water, on ice or gravel which will provide significantly less tractive resistance than a tarred surface. Picture if you will one tyre being on the tar and the other being on the gravel shoulder, in a non ABS fitted vehicle when brakes are applied the tyre on the gravel shoulder will lock up under far less braking pressure than the one on the tar. In the vehicle fitted with ABS the traction difference will be noted instantaneously and the amount of brake pressure on the wheel on the gravel will be mitigated ensuring the vehicle direction matches the driver intention.

The problem that off-road or gravel driving presents is that the co-efficient of grip is drastically reduced across all the tyres. This makes it very difficult for the ABS system to accurately modulate brake pressure across all four wheels and hence the overall braking performance is compromised. Some of the newer 4×4 vehicles have addressed this by bringing out off-road ABS. The system monitors the transfer case selector, when the vehicle is in 4X2 mode the standard ABS profile is operational and when the driver selects 4×4 a different ABS profile specifically mapped towards low traction states is selected. The primary difference in 4X4 ABS is that the system allows a greater amount of wheel lockup assisting the tyres to brake through the loose surface and find the firm under surface.

One of the more common safety hazards with standard ABS off-road occurs when brakes are applied during a failed hill climb. At the point where the vehicle struggles to make progress up the hill the correct procedure is to stall the vehicle thus utilizing the engine and the braking system to hold the vehicle in position. Many drivers however don’t follow this practice and merely stand on the brakes to gain control and stabilise the vehicle. What they don’t realise is that as the vehicle is braked the variation in surface traction at the wheels can cause the ABS system to activate preventing the brakes from locking up and thus preventing the vehicle from being held in position. The result is that the vehicle then starts going backwards even with full pressure on the brakes pedal and usually the angle of the climb will cause the vehicle to gain momentum rather than come to a halt. This scenario can be very dangerous as the driver feels disconnected from the vehicle and the only braking option available is to yank up the handbrake. In some vehicles when the rear axle difflock is engaged the vehicle will disconnect the ABS system as the manufacturers have recognised that the use of a difflock is usually associated with more technical off-road conditions than usual.

The key to operating any vehicle safely in any environment is an understanding of three key elements – speed, traction and tyre pressure and their direct relationship to each other in a given circumstance.

Speed directly relates to the amount of energy that is being added to a vehicle in motion. Newton’s first law: Inertia is the tendency of an object in motion to remain in motion, or an object at rest to remain at rest, unless acted upon by a force. The greater the speed the greater the force required to alter the vehicles state.

Traction is the ability of a mechanical force to maintain tension with a surface.

Tyre pressure has a direct influence on the tread profile presented to the surface.

Driving fast on a loose surface with overinflated tyres presents the worst possible scenario in terms of the vehicles ability to maintain directional stability let alone provide optimal braking performance in a an emergency situation. Adjusting tyre pressure on a loose surface will allow the tyre to absorb surface shocks and undulations while presenting additional tread to the surface to provide additional traction. The decrease in tyre pressure will however necessitate a decrease in speed to prevent damage to the tyre. Too low a tyre pressure will however also be detrimental as this will significantly reduce the tyres ability to maintain lateral stability while also significantly increasing the risk of impact damage or tyre failure due to excessive heat build up.

The message is to temper your speed and know the technical characteristics of your vehicle. Just because the brochure lists a feature under safety equipment does not mean that it is a safety feature in all conditions. Do yourself a favour and invest the time to familiarise yourself with all the features on your vehicle.

We may be experiencing a severe drought in the Eastern Cape at the moment but this may actually make mud driving more treacherous as sudden down pours of rain can have a dramatic effect on ground material causing many a hidden sink hole or soft patch waiting to catch the unwary driver.

The rustic splendour of the Eastern Cape brings with it a mix of off-road challenges , grassy tracks, river crossings and rural settlements to create a magical allure. However those not applying the correct levels of preparation can often find themselves in a spot of bother when the ground changes from gravel to mud. Rainfall has a dramatic effect on the terrain and hence a vehicles ability to navigate through the rivers and trails. Many areas form marshlands impassable by vehicle and in other areas the slopes become like soap bars.

All vehicles operate on a fundamental principle of traction to gain or brake momentum. Mud in a similar way to ice removes the predictability of the available traction resulting in the driver being surprised by a sudden lack of traction.

There are some basic principles to be applied when negotiating mud

Inspect the mud as it may vary in consistency – Mud can go from firm to slush and back to firm depending on the liquefaction of the soil. By simply using a stick to probe the consistency of the mud prior to entering the driver can get a good gauge of whether the vehicle will make good progress through the mud or simple break through the crust and “belly out “  in the mud.

Avoid deep mud if possible – Each vehicle has its own limitations in terms of ground clearance. Understanding the likelihood of your vehicle’s underside coming into contact with the mud is key to picking a route through the mud.

A lower gear can result in wheel spin, whilst higher gears will cause you to lose momentum – Gear ratios can hinder as much as they can help. The recommended gear selection for mud is 2nd gear low range. This gives the driver ample torque for the obstacle while allowing the safety of one lower gear if things get tough and a few higher gears if additional momentum is required. If you select 1st gear high range you must be sure that the vehicle will transition the entire obstacle in that gear as the driver has no lower gear option.

Use a diff lock – By its nature mud will provide differing levels of available traction to each wheel as the vehicle progresses. It is for this reason that all available traction aids should be engaged. The 2011 Grand Cherokee will come with selective traction control with a specific setting for mud and sand. The core difference in this setting is the wheels are allowed to spin to a greater extent than would be the case on rock. This additional rotation allows the tyres to self clean by using centrifugal force to expel the mud trapped in the tyre tread while at the same time shovelling the water and mud in front of the tyres under the vehicle.

If you start to generate wheel spin, decelerate to allow the tyres to find traction – The amount of rotation is a fine line between enabling the tyres to self clean while providing sufficient contact time to provide  traction. Excessive wheel spin does not provide traction. Just like electronic traction control prevents excessive wheel spin so too in a non traction control vehicle the driver needs to judge the amount of forward progress being achieved relative to the amount of acceleration being applied. Typically the wheels should spin 10%-15% faster than the vehicle is making forward progress.

Do not deflate tyres if the base is hard, if it is very wet tyre deflation will assist in flotation – I like to call this the 5 cm rule. If you stand on the mud and your foot only sinks 5cm into the mud then deflation to 75% of normal pressure will ensure the tread gains good traction while the best possible ground clearance is maintained. If your foot goes in deeper then deflation up to 50% of the manufacturers recommended pressure can be advised. This always needs to be considered in conjunction with the ground clearance requirements as deflation does affect ground clearance. The idea of the deflation is to extend the tread to provide added flotation so the gross vehicle mass is distributed over the largest surface area possible. If below 5cm the principle is similar to snow driving where very thin tyres are used to exert the greatest amount of pressure on a small area hence maximizing traction. If the mud is deep however the high pressure will prevent the tyre from flexing sufficiently to climb over ruts and hidden obstacles in the soft mud.

Change gears sooner rather than later – Particularly in turbo diesel vehicles it is critical to understand your vehicle’s torque band i.e. where the power comes in relative to the engine revs. When the clutch is depressed to facilitate a gear change the mud will immediately have a braking effect on the vehicle. It is for this reason that you need to check the rev counter prior to changing gears to ensure that when you change gear that you enter the torque band in the required gear to ensure good progress. If the engine revs are too low when the gear is selected it is likely that the new gear will have revs below the turbo boost and the vehicle will not make good progress.

If you are going to lose momentum, prepare for a quick transfer to reverse – If you have changed down to your lowest gear and the vehicle is still struggling to make forward progress prepare for a quick change to reverse. Use the wall of mud in front of your tyres in a manner similar to a skateboard half pipe. As you depress the clutch or go through neutral in an automatic the vehicle will rock back against the wall of mud in front of the tyres and this initial moment must be used to your advantage to gain your initial backward momentum. It is critical when reversing to reverse to a point that you are 100% sure will provide a suitable platform for your next attempt – rather reverse further out the obstacle that stop prematurely and get stuck.

Shallow ruts are easy to follow, but straddle deep ruts wherever possible – Ruts are very similar to train tracks in that once you are in them they are notoriously difficult to get out of. The idea is to put one wheel between the tracks and the other outside the tracks. This allows for maximum ground clearance. If the mud is very soft however it is preferable to go in existing tracks that have been compacted. Always note the exit point of tracks to make sure the rut track you choose did in fact exit the other side of the mud. If you do fall into a rut don’t fight the rut to climb out. Centre the steering wheel and ride the track until you exit the mud or you feel the depth of the rut has reduced to a point that you can climb out.

Ensure you know where your recovery points are before you enter the obstacle – Many vehicles don’t come with recovery points on the rear. There is nothing worse than having gotten stuck you now have to search in the mud for a recovery point. By simply checking prior to entry where the recovery point is recovery gear can quickly and easily be attached with the least amount of mudding of the driver.

Know the ability of your tyre to self clean – If you know that you may experience muddy conditions the fitment of a tyre that can process mud and self clean is essential in ensuring the technology of the vehicle can be transferred to the ground

If you want more details on the vehicle manufacturer affiliated off-road training programs we are involved with drop an e-mail to ralph@4x4training.co.za and I will gladly provide the details on how you could register for complementary off-road driver training.

Ralph Clark

Adventure 4X4 Academy

4×4 Vehicles can be described as any vehicle with 4 wheels and all 4 wheels are driven by the engine. There are many types of 4×4 vehicles with a variety of 4wd systems and suited to different conditions. There are basically 2 major groups of four wheel drive vehicles. Normal road cars with a 4wd system to improve on-road traction in wet or icy conditions, and those 4×4 vehicles designed to go where normal road cars cannot get to.

4×4 Vehicles for on-road use:

These vehicles are usually four wheel drive for improved traction in areas where slippery or icy road conditions prevail, or on high performance vehicles to improve cornering capabilities. These include vehicles used on good gravel roads like rally cars. 4wd systems in normal road 4×4 vehicles or rally cars was first brought to the world’s attention in the early eighties when Audi introduced their world beating Quattro models. Since those early days, 4×4 vehicles aimed at road use have gone from strength to strength. Almost all the mainstream manufacturers now have four wheel drive versions of the most popular models including Mercedes, VW, Volvo, BMW & Jaguar. Some manufacturers like Subaru only build 4wd versions of their models. Then there are the high performance road going 4×4 vehicles, like the Porsche 4wd models, Nissan GTR and Lamborghini’s.

4×4 Vehicles for off-road use:

These vehicles are those intended for use off the normal road in conditions where roads are very bad or there is almost no road. In the early days of the automobile, people realised that the new engine powered vehicles really struggled with traction in difficult conditions and that an improvement is needed. Engineers realised that if all the wheels on the vehicle can be driven, traction will be greatly improved over undulating terrain. It took many years for the 4wd system on 4×4 vehicles to be developed to a point where it was usable in main stream vehicle. Before World War 2 there were a few mildly successful 4×4 vehicles, but the development of the Willy’s Jeep during World War 2 led to a 4×4 vehicle revolution. The Jeep was a light weight vehicle which was easily adapted for civilian use, where 4×4 vehicles before this were all large heavy truck use for mining, construction and other commercial uses, as well as those that were used in military applications.

The light weight 4×4 offroad vehicles has slowly grown in popularity and is used in various applications from farming, to exploration, recreation and access to many previously inaccessible areas. Early 4×4 offroad vehicles were all very rough and hard like the terrain they are suppose to traverse, but in the early 70’s this change with the introduction of the Range Rover, a 4×4 offroad vehicle aimed at doing serious off-road work, but still comfortable and classy enough to go to church on Sunday.

Today there is a wide variety of 4×4 vehicles available to the consumer, from vehicles like the Land Cruiser and Patrol pick-ups that can work hard on the farm or construction site, to the Land Rover Defender that can conquer continents, to the classy SUV’s like the Pajero or Range Rover that can be used on the road for most of its life, but still able to engage low range and do relatively serious off-road work.

Each 4×4 vehicle has their own positive and negative points, and are intended for a variety of uses. They have different ability levels and different levels of comfort. Choosing the right 4×4 vehicle to suit your needs can be very difficult and this site is aimed at providing information on a large variety of 4×4 vehicles to make your choice much easier.

Read the follow up article to this, “How to choose a 4×4 vehicle”, to see what type of 4×4 vehicle will best suit your needs best and then look at the specifications of vehicles in that class.

4×4 Vehicles