Shock Absorbers - The Basics

How shock absorbers function?

Shock absorbers are an integral part of a vehicle’s suspension. A shock absorber is designed to absorb or dampen the compression and rebound of the springs and suspension. They control the unwanted and excess spring motion. Shock absorbers keep your tires in contact with the road at all times. Before going any further, let’s discuss some key terms that will help us understand how shock absorbers work. Back in elementary school we learned about energy, more specifically, we learned about potential and kinetic energy. We also learned about the Law of Conservation of Energy. The Law of Conservation of Energy states that energy cannot be created or destroyed, it can only change forms. Potential energy is stored energy and kinetic energy is energy in motion. Now, let’s get back to shock absorbers. When you hit any bump or dip in a road, your vehicle’s suspension and springs move so the tire can stay in contact with the road and absorb the energy. The shock absorbers dampen the movement of the springs by converting the spring’s kinetic energy into thermal (heat) energy. This thermal energy is then degenerated in hydraulic fluid. Shock absorbers are an oil-filled cylinder. When your vehicle’s suspension moves, a piston moves up and down through the oil-filled cylinder. The up-and-down movement of the piston forces small amounts of fluid through orifices (tiny holes) in the piston head. Since only a small amount of fluid is forced out, this slows down the suspension’s movement and dampens the compression and rebound of the springs. Shock absorbers are also velocity-sensitive. This means that the faster the springs are moving, the more resistance the shock absorber provides.

Why do you need to replace shock absorbers?

Shock absorbers keep your tires in constant contact with the road. Without shock absorbers, vehicles would continue to bounce up and down until all of the spring’s kinetic energy is depleted. Worn shocks can affect a vehicle’s driving and braking. Worn shocks increase the distance it takes for a vehicle to stop because a tire isn’t kept in complete contact with the road. It may also cause the front end of your car to “dive” when braking. Worn shock absorbers also increase the wear on tires and suspension systems. Without shock absorbers, driving, cornering, and braking would be very dangerous.

When do you need to replace your shock absorbers?
Leaking shocks are an obvious sign of worn shock absorbers. However, detecting a worn shock absorber may not be this easy. If your vehicle is bouncing or swaying excessively, you should have your vehicle’s suspension inspected by a professional. The best way to check if your vehicle is bouncing excessively is to drive over familiar roads and see if there is more bouncing than usual. You can also perform the bounce test. What you do is bounce each corner of your vehicle a few times, and after you let go, the vehicle should bounce only once and then settle. If your vehicle settles after one bounce your shocks are good. If the vehicle continues to bounce, your shock absorbers may be worn and should be checked. Experts recommend that you should have your shock absorbers checked once a year or every 12,000 miles.

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