Safe and fast driving, good acceleration without sliding, road hold in all conditions, improved stability, pick-up and drive-away also in critical conditions: these among the objectives in the design of a high performance car. For these purposes the advantages of 4WD (four wheel drive) are clear: torque distributed to four wheels, and so greater traction, and greater lateral grip for the driving wheels. In order to evaluate traction-handling-stability of a 4WD car, computing programs were developed, to estimate the performances of the main differentials, and to estimate their effect on the behaviour of a car when utilized in axle or inter axles. According to the results of the calculations, at the present state of technology, for a road high performance car, the best solution appeared to be the following: - full time 4WD, torque split about 50-50% between front and rear axle (perfectible according to the design and mission characteristics of the car) - central differential with viscous control - TORSEN rear differential.
Abstract