5 reasons to not use SUV's for off-road
In my previous advice I have explained: How to choose a capable off-road car? based on low range, ABS and Diff-locks. In this advice I will explain why SUV’s and crossovers do not make good, capable off road vehicles. The SUV’s / crossovers have serious design flaws (or differences) that make them unsuitable as off road vehicles. Below are the 5 points that will make this class of vehicle unsuitable as off road vehicles.
1) SUV’s have poor suspension articulation
Main part of the reason why proper off road vehicles can do what they do is the fact that they have a long suspension travel, otherwise known as “suspension articulation”. What this means in the real world is that these vehicles can cope with uneven terrain because the suspension systems allow the wheels to move for up to 40 inches (1 meter) and more with respect to each other.
This means that even on extremely uneven terrain, all the wheels can remain on the ground, thus maximizing the traction. In the case of SUV’s and crossovers, the maximum suspension travel is about 9-10 inches (seldom more), which means that once a wheel has moved as far as the suspension allows it to travel, the part of the vehicle lifts off the ground. When this happens, one or more wheels lose traction and if the vehicle is not fitted with diff locks, the vehicle is stuck, and has to be towed out of the obstacle, or uneven terrain.
2) SUV’s are not flexible enough
Proper off road vehicles that have separate, “stepladder” chassis are extremely flexible, which also helps to keep all the wheels on the ground. In combination with their long, built-in suspension travel, this means that a proper off road vehicle can negotiate types of uneven terrain that no SUV or crossover ever can, simply because SUV’s cannot “bend” enough to allow the wheels to remain on the ground.
3) SUV’s do not have enough ground clearance
While some SUV’s have about the same ground clearance as many proper off road vehicles, the problem is that their suspension setups do not allow for heavy loads. This load is sometimes made up of up to seven passengers, but in most cases, the load comes from the suspension being too soft.
When an SUV goes over, say, a bump, the vehicle drops down too low when the suspension compresses as the vehicle leaves the obstacle, and especially so when the vehicle is travelling too fast. Since the suspension compresses too much, the vehicle’s ground clearance can be reduced to the point where some components like differentials, cross members, and even the engine and transmission can hit obstacles like rocks.
Proper off road vehicles do not have this problem, because their hard suspensions do not compress to the point where ground clearance is affected in meaningful ways. Moreover, because proper off-road vehicles have hard suspensions, its ground clearance actually increases when one or more wheels go over an obstacle, since the vehicle’s weight is always fully supported by the firm suspension(s).
This is not always the case with SUV’s, since their suspensions were designed to move in such a way that uneven spots are absorbed without excessive body roll or movements. Thus, the vehicle is not lifted off the ground when one or more wheels pass over an obstacle, and if the vehicle is loaded with passengers, it could happen that even small obstacles could hit one or more critical components.
4) SUV’s are overly complicated
The ideal off road vehicle has as few components as possible to make it work, with driver and passenger comfort coming a long way behind requirements like reliability, ease of use, and easy repair ability.
This is not the case with luxury SUV’s and crossovers that are designed to give the driver and his passengers the most comfortable ride possible on hard, paved roads. While we agree that some SUV’s are able to complete short and easy level 1 off road trails that are designed with SUV’s in mind successfully, the problem is that SUV”s are too complex (complicated) to do anything else reliably.
Part of the problem is that the electrical systems of modern SUV’s are not designed to cope with the heat, dust, and vibration that go with serious off road driving. In many cases, the air suspensions of these vehicles are protected by dozens of fuses, relays, and control units that were simply not designed to cope with the demands of off road driving conditions.
No vehicle that can be completely disabled when a single fuse blows (such as when the compressor stops working when its fuse blows) can ever be trusted on a long, difficult off road trail, and especially a trail that requires extreme care by an expert driver.
5) SUV’s do not have recovery points
It is one thing to clown around on some loose sand, or to drive an easy, level 1 trail when there are plenty of other vehicles around to supply a tow, but it is something else entirely when that vehicle has to be recovered in very difficult terrain. For instance, a vehicle that is stuck in sand up to the depth of the tyre sidewalls, can require a force of up to three times the force required to move it if it were on a hard surface.
This force is calculated by using the weight of the vehicle as a base line; therefore if your vehicle weighs say, 1800 kgs, you will need a force that is equal to the vehicle’s weight, plus ten percent of that value to move it on a hard surface. In this instance, you will need a pulling force of at least 1980 kg.
However, if as we said, the vehicle is stuck in sand up to its rims, you need at least three times that pulling force, thus, 5940 kg, and that is where the problem comes in. Even if there is a vehicle with a winch available, there is no attachment point on the stuck vehicle that is strong enough to withstand this pulling force, and it is almost certain that the normal towing point or recovery eyelets will tear out from the vehicle- leaving the vehicle stuck in the sand, and probably hurting someone as the winch cable snaps and recoils.
Depending on circumstances and local conditions, the required pulling force can be as high as six or even seven times the value of the baseline figure, which should make it obvious that unless the vehicle has properly rated recovery points, it should not be used off road, and most certainly not in conditions where it might have to be towed out with forces that exceed its weight by several times.
SUV’s are simply not designed to withstand pulling forces of this type, and any attempt to subject a vehicle to these forces is irresponsible, dangerous, and likely to hurt someone.
So, no, SUV’s and crossovers do NOT make good off road vehicles, even if it is only because they cannot always be recovered safely.