How suspension works: Dampers

Unseen and often not considered, dampers are one of the keys to your car's on and off-road capability. In fact, they are so important to a vehicle's performance, racing teams around the world spend countless hours and endless dollars fine tuning them.

But what are dampers? What do they do? How do they work? Why are they important and what are the warning signs they need replacing?

Let's start by explaining what a damper is. It's a long metallic cylinder sealed at both ends, with a piston protruding at one end and they are a major component of the suspension, with one connected to each wheel. In most cases the cylinder is filled with hydraulic fluid. Without getting too technical, there are different types of dampers available, even adjustable ones but essentially, they all do the same job.

What do they do?
Let's start with one thing dampers don't do. They don't support the weight of the car. Instead, that's the job of the springs, another type of major suspension component.

What dampers do is control the bouncing movement of the spring by providing resistance, to ensure the tyres are kept in contact with the road.

Think of it like this: when you bounce a ball and catch it, you are controlling its bounce. If you don't catch it, the ball continues to bounce with each bounce progressively smaller until the ball comes to rest. A car without dampers would behave the same way. After hitting a bump it would bounce up and down continuously, until it finally settled in its normal state.

The damper, like you catching the ball, controls the bounce.

Essentially, dampers do two things. Apart from controlling the movement of springs and suspension, dampers keep your tyres in contact with the ground at all times and whenever a tyre loses contact with the ground, your ability to drive, steer and brake is compromised.

And if the springs are allowed to bounce uncontrollably, the car will wallow and the ride quality will lead the car's occupants to feel sick after a while.

How do they work?
Inside the damper's sealed cylinder are valve passages and hydraulic fluid. As the suspension travels up and down, the piston moves inside the cylinder. As this occurs, the flow of fluid is slowed by the valve passages, which in turn controls the speed of the piston's motion and therefore the movement of the suspension. Dampers automatically adjust to road conditions and the faster the suspension moves the more resistance the dampers provide.

Why are they so important?
Dampers play a vital role in the ride and handling of your car.

Aside from giving you a comfortable ride, dampers help manage a vehicle's stability, cornering, handling, traction, braking, stopping distance, and overall safety.

But dampers tend be one of the most overlooked maintenance items on a car.

Unlike a flat tyre or blown headlight globe, dampers' performance deteriorates gradually over a long period of time, and often unknowingly, drivers adjust their driving style to compensate.

How can you tell they need replacing?
When your car is moving, the dampers are constantly working, so they do wear out. But there are warning signs to tell you your dampers need replacing.

Nose diving or swerving when braking hard indicate that worn dampers can no longer control the weight transfer of the car and the piston in the damper is compressing too rapidly.

After hitting a bump, your car should fall and rise back to its original position and settle after one, or two rebounds at most. If it doesn't, it means the dampers are worn out as they no longer control the bounce of the springs.

When dampers are worn, cars become more unstable, which is magnified in SUVs and LCVs due to their added height and weight.

Rock and roll might be great to listen to but it's no fun when cornering. If your vehicle leans excessively in corners, it's another tell-tale sign that the dampers are worn.

Yet another clue is vibrations through the steering wheel. Often it is simply a wheel out of balance but it could well be one damper is more worn than the other, creating an uneven controlling of the suspension.

Uneven or premature wearing of tyres is another sign of worn dampers caused by the shock's inability to control the suspension, causing the tyre to bounce on the road over bumps and through dips and wear unevenly.

If you have the wheel off and notice there is leakage from the shock, or the bushes are cracked and squashed, then it's time to bin them and get new ones. The same applies if the cylinder is damaged or dented on the outside as there's a good chance they're damaged on the inside and not functioning to their potential.

And when it comes time to replacing dampers, do so in pairs, otherwise uneven controlling of the bounce by one side of the car to the other will occur, causing an uncomfortable and uneven ride and compromise the car's stability.

Connecting your car to the road are four postcard-sized contact areas of the tyres. It is important to have your dampers operating properly to ensure you have the maximum grip and control through these contact patches at all times.