Driving Wizard®

                     What is; resonance roll?

Resonance roll is a condition in which the vehicle is induced to roll from side to side at its natural roll frequency. It is usually as a result of steering back and forth from one side to the other.

Energy stored in the suspension builds up as it repeatedly transfers from one side to the other, increasing the roll each time, until the vehicle may slide, spin-out or overturn.

It commonly occurs in trucks or vehicles with high or unstable loads, especially vehicles towing trailers. It can also be a factor in car crashes where a driver suddenly corrects the steering in a vehicle that has veered off the hard shoulder, or swerves to avoid an obstacle.

The best remedy is to allow a vehicle to stabilize on its suspension by steering straight (momentarily) before making another course correction.

So if you have to suddenly swerve around an obstacle, the best method is to swerve-stabilize-correct, rather than swerve in one direction and then suddenly swerve in the other direction.

Of course, when faced with a real emergency, it is difficult to overcome your natural instinct to make violent and rapid course changes. This is why electronic stability control (fitted to most new vehicles) has been such a lifesaver.

                             What is; short shifting?

"Short shifting" is a term mainly used in motor racing and truck driving circles, to describe changing up to the next gear, sooner than would normally be the case.

For example, a racing driver may change up to the next gear before optimum engine revs are reached, due to grip level, or to save fuel.

Truck drivers also use this technique when their trucks are lightly loaded, or when on down gradients as revving the engine to the rev limiter is simply wasting fuel. Often drivers simply skip one, or even several gears if they are not needed.

Car drivers can also use the same technique when starting-off on down gradients, changing up through each gear sooner than normal. In other words using gravity to do most of the acceleration, rather than engine power.

This is a good fuel saving strategy.

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