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.
0 comments: