What are shock absorbers?

Shock absorbers, also known as dampers, are key vehicle components that help smooth out lumps and bumps in the road. These simple but effective car parts turn the motion (kinetic energy) generated when going over a bump into heat (thermal energy) and disperses it to keep you safe and comfortable as you drive.

While they’re often a ‘fit-and-forget’ part of your car, understanding how shock absorbers work and knowing the signs of failure is essential for ensuring a safe and smooth ride for you and your passengers. In this article, we’ll cover what shock absorbers are, how they work and how you can spot the signs of damage.

Shock absorbers are a vital part of your vehicle’s suspension, and work with the springs to maintain a safe and consistent ride. You’ll find shock absorbers fitted behind the tyres in your car. They often look like a long strut surrounded by a large spring.

They’re fixed to the vehicle and control the fluctuations in the road surface to keep the car safe and stable. They help to improve braking and handling. Perhaps most importantly, they make the ride more comfortable for anyone inside the car.

Most car shock absorbers are based around a simple hydraulic system consisting of a piston housed in a cylinder containing hydraulic oil surrounded by a spring. As you go over a bump, the spring absorbs the force of the bump, and the action of the piston moving through the cylinder, forcing the oil through a series of valves helps to dampen the impact.

Together, the spring and the shock absorber help to keep your car level on the road during acceleration, braking and cornering.

Shock absorbers have a tough life and typically last between 5-10 years (or approximately 75,000 miles), but this depends on mileage, driving conditions and damage.

People with off-road vehicles or those regularly driving on poor-quality roads or carrying heavy loads may need to replace theirs much sooner.

Shock absorbers are checked as part of your annual MOT. MOT Testers are looking for shock absorbers that are secure and aren’t leaking fluid, or damaged so that they don’t function or have negligible damping effect.

Even if your car has passed its MOT, the shock absorbers may need replacing. Some of the tell-tale signs your car’s shock absorbers aren’t functioning properly include:

• Vibrations through the steering wheel: When you're driving, your steering wheel will pick up noise from the road and vibrate a little, but if it's happening regularly or the bumps are getting worse, it could be a problem with your shocks.
• Uneven car tyre wear: Tyres should wear evenly across the tread, but a worn-out or damaged shock absorber could cause one (or more) tyres to wear out more quickly. Patches or flat spots of tyre wear can be caused by a worn shock absorber.
• Nose dive when braking: If you feel your car is diving when you brake it’s likely that your front shocks have lost fluid or have weakened which is affecting their ability to damp and rebound.
• Taking longer to slow down: As well as nosedive, damaged or worn shock absorbers can reduce the effectiveness of your brakes, increasing the time it takes to slow down.
• Car feels like its swerving: Shocks keep your car stable on the road, but when they wear it can make it feel like your car is swaying and swerving.
• Rattling sounds: Any rattle in your car is worth investigating and could be caused by a damaged shock absorber, or broken spring.

Leaking or damaged shock absorbers could be an MOT failure and therefore should be replaced. If you spot any of the signs above, it's worth having your shock absorbers checked out by a qualified mechanic.

You must replace shock absorbers in pairs (the front or rear). This ensures your car maintains consistent damping, maximising the performance of the brakes and improves tyre life.

You can find shock absorbers alongside all the car parts you need for your car at Halfords. It’s important that you only use shock absorbers that are suitable for your car, as fitting the wrong type could be dangerous.

To find the right shock absorbers for your car just enter your registration number and you’ll only see the suspension parts that will fit your vehicle. Be mindful that some cars use different shock absorbers for the front and rear. If you’re unsure, you can always speak to one of our experts.