Learn something new every day
More Info... by email
Automobiles with front-wheel drive-trains (FWD) are often subject to what is called torque steering. As the name implies, torque steering is essentially the application of too much power, or torque, to the driveshaft of one front wheel too quickly. Thus, the over-powered wheel spins quicker than the other, resulting in the auto pulling to one side under heavy acceleration.
The most common mechanical cause of torque steering is uneven driveshaft lengths, and the uneven twisting of the shafts under acceleration. With this uneven length, engine power is transferred to the wheel with the shorter driveshaft a fraction of a second before it reaches the opposite wheel. This first wheel gains traction and pulls the vehicle toward that direction before the other wheel can gain enough traction to compensate. As acceleration is increased, traction and lag in the front wheels are also increased exponentially. Hard acceleration, therefore, leads to high torque steering.
Apart from differing driveshaft length, other mechanical causes of torque steer include poor tire sidewall design, engine movement from side to side that is the result of differing flexibility in engine mounts, and differences in road surface beneath the separate front wheels. While the mechanical problems associated with torque steering are fixable, each is expensive and ordinarily beyond the capabilities of the average driver. Examination of an auto’s FWD system by a prospective buyer before purchasing or driving the vehicle ought to alert the buyer to potential steering torque problems. Autos with a double-wishbone suspension, for example, are less prone to steering torque issues.
It’s obvious, however, that the most effective and least costly method in mitigating torque steering is to maintain steady incremental acceleration of a vehicle from a stop. Gentle acceleration allows both wheels to maintain even traction. This controlled traction will keep the vehicle headed in the desired direction, with little or no pull to one side.
Steering wheel torque, steering stem torque, and power steering torque, though occasionally equated with torque steering, are actually separate system dynamics having to do with the actual movement of the steering wheel, and the effort needed to turn the auto. Each may, however, contribute to the effects of torque steer, either positively or negatively. Steering wheel torque, steering stem torque, and power steering torque involve the actual force required and delivered by the steering system in turning the wheels in the direction desired. Steering torque is as much dependent on driver muscle power as on any power-assisted mechanical means. Torque steering essentially overpowers steering torque, taking steering control, at least momentarily, out of the hands of the driver.