Spring Failure

• Constant bouncing and cycling causes the spring's metal to heat up slightly. Over time, this constant heat cycling causes it to soften and sag. A sagging spring will manifest as a visible drop in ride height at one corner. To test the spring's stiffness, either slowly push down on the fender or pull up on the wheel arch. If the car's body moves with little or no effort, then the spring is probably worn out.
  
  

Damper Test

• Shock absorbers or dampers enhance the car's handling by slowing the wheel's travel up and down in the wheel well. Without a shock absorber, the strut would act like a pogo stick, bouncing up and down until it ran out of energy. To test the damper, place both hands on the fender, give it a sharp shove downward and release it. The body should spring back up and settle without bouncing downward again. If the body continues to bounce up and down after that initial shove, then the shock is bad.
  
  

Mechanical Failure

• Mechanical failures are fairly rare, and usually revolve around a loose bolt, worn-out rubber bump stop or bent component. These failures can manifest as anything from bad handling to bumping, banging or rattling over bumps.