Search Results

One cause of vehicle disturbance is smooth road shake. Manufacturers are attempting to reduce vehicle sensitivity to shake input forces from tire-wheel assemblies by changing suspensions and body-frame structure, stiffness, by tuning engines on rubber mounts, relocating body mounts, and so forth. The similarity of tire nonuniformity and wheel radial runout, and the laboratory and production techniques for matching tire and wheel are described. The conclusions reached are that matching tires to wheels would be an effective stop-gap measure; that the ultimate goal is improvement in tire uniformity and wheel runout to the point where matching would be unnecessary; that tire lateral force variation and lateral wheel runout are not related to smooth road shake.

Original equipment tires and wheels on today's automobiles use new finishing operations that greatly reduce the radial force variation of the tire-wheel assembly resulting in improved ride quality. This paper presents radial force variation levels for past, present, and future combinations of tires and wheels.

A new laboratory test facility for measuring the various understeer influences on complete vehicles is described. The machine actuates the body and suspension in the same manner as it occurs on the road while turning or braking. Changes in steer and camber angles of the wheels are measured as body roll, tire lateral forces, and tire aligning torques are applied to the vehicle separately or simultaneously. It makes a direct measurement of vehicle roll susceptibility (tendency to roll in a turn). Steer caused by braking, called brake steer, is measured by applying brake forces. A description is given of the systems and interacting subsystems of the machine, which provide duplication of a wide range of actual over-the-road conditions while preventing application of unrealistic constraints to the vehicle. Design features that create the capability to obtain the desired accuracies while minimizing test time are also discussed.