Introduction:
The rear suspension system plays a very important part in ride quality and in the control of suspension and differential noise, vibration, and shock. Although the front wheels actually steer the vehicle, the rear suspension is also vital to steering control. The rear suspension must also provide adequate tire life and maintain tire traction on the road surface. Rear suspension systems described in this chapter include live-axle, semi-independent, and independent.
Vibration Theory
Vibrations have these three elements:
1. Source—the cause of the vibration
2. Path—where the vibration travels through the vehicle
3. Responder—the component where the vibration is felt.
For example, if the vehicle has an unbalanced tire, this is the vibration source. The vibration path is the steering and suspension system through which the vibration travels. The responder is the steering wheel because this component is where the customer feels the vibration. When diagnosing vibration problems, locate and correct the source of the vibration. In the previous example of the unbalanced tire, installing a rigid brace from the steering column to the instrument panel and chassis may reduce the vibration experienced by the customer, but this does not solve the problem. To eliminate the problem, also diagnose the unbalanced tire condition and then balance the tire-and-wheel assembly.
Vibration cycles
Vehicle vibrations may be tested with an electronic vibration analyzer (EVA).