Fishtailing is a

vehicle handling Automobile handling and vehicle handling are descriptions of the way a wheeled vehicle responds and reacts to the inputs of a driver, as well as how it moves along a track or road. It is commonly judged by how a vehicle performs particularly durin ...

problem which occurs when the rear wheels lose traction, resulting in

oversteer Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Oversteer is what occurs when a car turns (steers) by more than the amount commanded by the driver. Conversely, understeer is what occu ...

. This can be caused by low friction surfaces (sand, gravel, rain, snow, ice, etc.). Rear-drive vehicles with sufficient power can induce this loss of traction on any surface, which is called power-oversteer. During fishtailing, the rear end of the car skids to one side, which must be offset by the driver counter-steering, which is turning the front wheels in the same direction as the skid, (e.g. left if the rear swings left) and reducing engine power. Over-correction will result in a skid in the opposite direction; hence the name. Without a proper driver's reaction, the fishtailing vehicle will spin completely. Friction is the main reason this action is effective. If a car is moving across a surface in any direction other than the direction it is pointed, it is skidding (or sliding), and a sideways load is being imposed against the tires. This causes a lot of friction, even if the tires are allowed to rotate freely. By turning the front wheels into the direction of the skid, the front wheels will become aligned with the direction of travel. The side load will no longer be imposed against the front tires, and they will then roll freely to match the speed of the vehicle. This reduces the friction between the front tires and the surface. But the rear tires will still be sliding sideways, and the greater friction that exists will cause the back end to trail directly behind the front end, similar to a shuttlecock in flight, thus the car straightens out. As the car straightens, the front wheels must be kept aligned with the direction of travel to keep the friction of the front tires at or below the friction of the rear tires, or a skid in the opposite direction will quickly develop. The key is to keep the front wheels aligned with the direction the vehicle is moving-not the direction it is pointed. Most modern rear wheel drive cars solve this problem by using a form of

traction control A traction control system (TCS), also known as ASR (from german: Antriebsschlupfregelung, lit=drive slippage regulation), is typically (but not necessarily) a secondary function of the electronic stability control (ESC) on production motor vehicle ...

which limits engine power when fishtailing occurs. The ability of the rear suspension to keep tires in contact with, and perpendicular to the road is also a key factor in the amount of grip available through the rear axle. For example, a live

beam axle A beam axle, rigid axle or solid axle is a dependent suspension design in which a set of wheels is connected laterally by a single beam or shaft. Beam axles were once commonly used at the rear wheels of a vehicle, but historically they have als ...

suspension Suspension or suspended may refer to: Science and engineering * Suspension (topology), in mathematics * Suspension (dynamical systems), in mathematics * Suspension of a ring, in mathematics * Suspension (chemistry), small solid particles suspend ...

will have far less grip on a bumpy road than an

independent rear suspension Independent suspension is any automobile suspension system that allows each wheel on the same axle to move vertically (i.e. reacting to a bump on the road) independently of the others. This is contrasted with a beam axle or deDion axle system in w ...

, due to its far greater

unsprung weight The unsprung mass (colloquially unsprung weight) of a vehicle is the mass of the suspension, wheels or tracks (as applicable), and other components directly connected to them. This contrasts with the sprung mass (or weight) supported by the ...

, and forces from one wheel being transmitted through the axle to the other wheel, leading to the tire being out of contact with the road surface more of the time Similar behavior is evident during heavy braking in all types of road vehicles, due to

weight transfer Weight transfer and load transfer are two expressions used somewhat confusingly to describe two distinct effects: *the change in load borne by different wheels of even perfectly rigid vehicles during acceleration *the change in center of mas ...

to the front. This can be mitigated by re-proportioning the braking forces (more to the front, less to the rear) to keep the rear wheels from locking up. Most modern cars use

anti-lock brakes An anti-lock braking system (ABS) is a safety anti-skid braking system used on aircraft and on land vehicles, such as cars, motorcycles, trucks, and buses. ABS operates by preventing the wheels from locking up during braking, thereby maintainin ...

(ABS) which addresses this problem. Older cars may have less sophisticated technical systems for lessening this tendency or the driver alone must actively modulate the brakes. Fishtailing may be the result of the police pursuit technique called the

PIT maneuver The PIT maneuver (precision immobilization technique) or TVI (tactical vehicle intervention) is a pursuit tactic by which a pursuing car can force a fleeing car to turn sideways abruptly, causing the driver to lose control and stop. It was d ...

, in which the driver of a pursuing vehicle deliberately induces directional instability in a pursued vehicle with the intent of spinning it off the road.

References

{{Automotive handling Automotive safety Driving techniques

See also

References