"Torque Steer"... What and How Dangerous Is It?

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"Torque Steer"... What and How Dangerous Is It? This is "Torque Steer"...

Definition: The annoying, and sometimes dangerous tendency of some front-wheel
drive (and 4-wheel drive) vehicles to pull to one side when engine torque is applied.
In other words, you step on the gas and the car wants to steer right or left.
In severe examples, decelerating also has the opposite effect.
The car then pulls to the other side.
By redesigning the power train to use equal length half shafts between the transaxle
and wheels, the tendency towards torque steer can be greatly reduced.

Torque steer happens when your engine is steering the car, not you.
Pounding on the accelerator causes the car to twist in the direction of the tire getting more
torque.

Torque steer is created from a moment or leverage arm created by the relationship between
an imaginary line projected through the Kingpin inclination angle and the centerline of the tire.
Kingpin inclination angle is the line drawn through the upper and lower ball joints on a
multilink car and projected to the ground.

On a MacPherson strut car, it's the line drawn between the upper shock mount through the
ball joint as projected to the ground. The distance from this point to the center of the tire's
contact patch is a moment arm or a leverage point where the torque can pull the steering off center.

Another cause of torque steer is unequal length driveshafts. When the axles are not of
equal length, the CV joints are at unequal angles. This allows more torque to reach one wheel
(sooner) than the other. Nonsymmetrical driveshaft angles (including equal axle length
cars when cornering) and lengths are the primary cause of torque steer but the problem can
be compounded by suspension, worn or loose control arm bushings, worn or loose tie rods,
broken or loose engine mounts, engine movements, alignment, unequal tire pressures, and road surface.
Denser engine mounts can keep the engine from shifting during acceleration.

Other definations include the following:
Root causes for Torque Steer are:
� Nonsymmetric driveshaft angles, e.g. due to
... Nonsymmetric design of the vehicle, e.g. different driveshaft length
... Transient movement of the engine
... Tolerances in engine mounts
� Different driveshaft torques left to right
� Suspension geometry tolerances
� Unequal traction forces due to road surface (m-Split) in combination with
Kingpin Offset

FORD: - Torque Steer Influences on MacPherson Front Axles: Click Here!

Check also: Click Here!

Comment: If the situation is so easily observed in common road cars; what happens when
an OEM turbo motor with more than twice the available torque is swapped into a FWD car
or a turbo kit doubles the previously available torque at the wheels?...
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Walk softly... and carry a BIG stick!