Corrugated sheet metal
Corrugated iron is an inescapable part of 4x4 travel and trail running, and a stressful experience for driver, passengers and car!
This “corrugated sheet metal CSM” phenomenon is caused by vehicles passing over dirt tracks.
Small bumps resembling corrugated iron are formed, hence the name.
The amplitude of the peaks and troughs is often very different from one track to another, depending on the nature of the terrain, the presence or absence of sand and the hardness of the soil.
One thing's for sure: it's going to be a bumpy ride!
The technique is simple: accelerate quickly so that the wheels only touch the top of the bumps, and you “fly” along the track.
As each CSM has a different amplitude, the “ideal” speed will also be different. Many factors play a part in determining this “ideal” speed: the amplitude of the plate, the distance between the two axles of the vehicle, the size and pressure of the tires, the pressure, the weight of the vehicle, etc.
The hardest part will be getting from 0km/h to the “ideal” speed as quickly as possible.
During acceleration, the whole car is shaken up, there's noise on all sides and you'd think all the bolts were going to explode.
That's why you need to keep this interval to a minimum, and don't hesitate to accelerate hard.
Légende
1 Tôle ondulée
2 Espace entre chaque bosse
Figure A
When driving slowly, the 4x4 hugs the bumps of the corrugated sheet. The result is enormous vibrations, very unpleasant for driver and passengers. They also damage all the car's components (shock absorbers, steering and slient-blocks).
Figure B
At higher speeds, the wheels only touch the top of the bumps and the car “flies” over the metal.
Vibrations are much less severe, and this takes the strain off both the mechanics and the passengers.
So we're looking for that “ideal” speed, which will be different for every 4x4 and every track.
You have to be honest and look for the best compromise; it's usually between 60 and 80km/h. It's very impressive the first few times, but don't be afraid to step on the gas.
On corrugated sheet metal, grip is very poor; take this factor into account in your driving, and leave plenty of space between vehicles!
When braking, imagine you're on snow - the effect is almost the same: more grip.