Shock absorbers use valving of oil and gasses to absorb excess energy from the springs. Spring rates are chosen by the manufacturer based on the weight of the vehicle, loaded and unloaded. Along with smoothing out bumps and vibrations, the key role of the shock absorber is to ensure that the vehicleƒ??s tires remain in contact with the road surface at all times, which ensures the safest control and braking response from your car. Signs of shock absorber failure includes vibrations while driving, nose diving while braking, bouncy ride, uneven tire wear etc.