The effect of the front-to-rear wheel torque distribution on vehicle handling: an experimental assessment

The front-to-rear wheel torque distribution influences vehicle handling and, ultimately, affects key factors such as vehicle safety and performance. At a glance, as part of the available tire-road friction is used for traction on the driven axle, a Front-Wheel-Drive (FWD) vehicle would be expected to be more understeering than a Rear-Wheel-Drive (RWD) vehicle with equivalent characteristics. However, in specific conditions such effect may be counterbalanced, or even reversed, by the yaw moment caused by the lateral contribution, in the vehicle reference system, of the traction forces at the front wheels. This paper discusses the experimental assessment of the phenomenon in steady-state cornering, for a fully electric vehicle with multiple motors, allowing different front-to-rear wheel torque distributions. The results confirm that the yaw moment effect of the front traction forces is significant, especially at low vehicle speeds and high lateral accelerations. In particular, in the case study maneuvers, the RWD configuration of the vehicle resulted more understeering than the FWD one at the speed of 30 km/h.

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