How do shock absorbers work

We all enjoy a smooth ride when we’re driving, but have you ever given any thought to the components that allow us to travel over terrible road surfaces with barely a bump? Most drivers have heard of the shock absorber, but they tend to be a misunderstood component and unless a mechanic says they need to be replaced, they barely get a second thought.

However, driving on worn shock absorbers can be dangerous, as loss of tyre grip on the road due to a worn shock absorber is a recipe for disaster.
So what exactly is a shock absorber?

Oddly enough, shock absorbers don't actually absorb any of the shocks felt when driving. This is the job of the shock absorber’s counterpart, the suspension spring. When the vehicle hits a bump, this spring compresses, soaking up and storing the energy of the impact. This is what absorbs the bump and prevents it from entering into the cabin of the vehicle.

This energy must be released and it’s the job of the shock absorber to slow this release of energy and keep the tyre on the road surface. It does this by turning the springs energy into heat. The more accurate term for the shock absorber is a damper, as it dampens the energy released from the spring to keep the vehicle controllable.

How does it do all of this? And what does it mean when I have a ‘worn out’ shock absorber?
Shock absorbers are filled with oil, and a specially designed piston moves inside of the shock absorber as the vehicle moves. The oil inside is forced through many small holes and valves inside the piston and this controls the resistance. This resistance converts the spring’s released energy into heat.

Confused? Time to give a more real world example.

If you place your hand in water and move it back and forth slowly, you don’t feel much resistance. This is the same resistance a shock absorber would feel on smaller or slower bumps. If you increase your hand speed, the resistance increases and it requires more energy to ‘push’ against the water. This is the same as a shock absorber working overtime on a rough road.

If your shock absorbers are worn out, this means they are failing to effectively convert the energy released from the springs. This can lead to your vehicle bouncing all over the road and, in some cases, the tyres losing contact with the road surface making the vehicle uncontrollable. As a rule of thumb, it’s best to have your shock absorbers inspected for wear and leaks every time your vehicle is in for a service and many manufacturers recommend shock absorber replacement every 100,000km to keep your vehicle handling the ups and downs of everyday driving safely.

Not sure which shock absorbers are suitable for your vehicle and driving style? AutoGuru has a guide for that.