The “shock” is a suspension component that controls the up-and-down motion of a vehicle’s wheels. Though the devices provide some shock absorption, the job of absorbing shocks is handled mostly by the springs. More accurately called dampers, “shocks” damp excessive motion, keeping the vehicle’s body from bouncing down the road. Cars with worn-out shock absorbers illustrate what the devices are meant to do, because they tend to bounce continuously. Worn-out shocks compromise a car’s roadholding and braking. The bounce test is a time-honored method of checking shock-absorber health, but mechanics might also spot oil leaking from the shock, which means the component is starting to fail and should be replaced. Uneven tire wear is another sign of shock failure.