Car shock absorbers: what are they and why are they needed?

Car shock absorbers: what are they and why are they needed?

What are car shocks?

Car shocks are a fundamental component for the driving , comfort and safety of our car. We often tend to forget their importance compared to other equally important components such as engine oil, tyres or brake pads.

They are part of the vehicle's suspension system along with the suspension springs. In some models they are placed inside the suspension springs to save space and allow faster maintenance of the entire suspension system.


Car shock absorbers are almost always placed behind the tires and connect the suspension arms to the vehicle body. Their operation allows for a comfortable and safe ride, helping to keep the vehicle stable while driving.

How are car shock absorbers made and how do they work?

While car shock absorbers on the outside may look like a simple metal cylinder with a ring on each end, they are actually much more complex components. To understand the importance of shock absorbers, it is essential to know how they are made and how they work. So let's explain it as simply as possible.

Car shock absorbers consist of two cylinders that slide into each other and a piston directly connected to one of the two cylinders. The inside of these two cylinders is filled with oily fluid, a common hydraulic fluid, into which the piston connected to the other cylinder flows. In the head of the piston, always submerged in the oil, there is a washer with many holes that allows the precise movement of the piston.

Without having to give a mechanical engineering lesson, we just need to know that the oil, thanks to its particular viscosity and to the holes of the piston washer, sets a strong resistance to the vertical movement of the piston. Therefore, the piston is slowed down in its movements a bit like when you try to run on the beach and you are "slowed down" by the water.


As a more practical example, when the car goes over a bump the shock is stretched and then compressed. The piston is forced to move vertically between the two cylinders but, instead of stretching back and forth, it is slowed by the resistance of the oil passing through the bores.

This deceleration allows the machine to absorb all the imperfections of the road without being "jolted" on one side or the other by the suspension springs. In fact, remember that without shock absorbers the suspension springs would translate any tension in the opposite direction, making driving impossible.

What are the differences between shock absorbers and suspension springs?

As we have seen, shock absorbers and suspension are two components that always work closely together. They are a bit like the Ying and Yang of the car, one is meaningless without the other. At the end of this poetic moment, let's quickly illustrate the roles of each:

  • Suspension springs (or simply suspension) are elastic components that are almost always shaped like a large spring and connect the car's chassis to the tires. Thanks to their elasticity, they absorb all the stresses and imperfections in the ground that would otherwise pass through the bodywork to the car's passengers. They are black or grey on small cars and have bright colours on large SUVs or sports cars.
  • Car shock absorbers are oil-filled cylindrical components inside which a piston slides. By exploiting the viscosity of the oil, which slows down and tunes the vertical movement of the piston, the dampers attenuate the movement of the suspension. The shock absorber has a stabilizing effect on the suspension and allows a safe and smooth ride.

Therefore, we can conclude that both shock absorbers and suspension are essential parts of the car. Without them, any stress on the road surface could destabilize the car and make driving unpleasant or, in the worst case, create safety hazards.


What is the warning light for car shock absorbers?

Generally car warning lights figuratively indicate the type of parameter they inspect. The car battery light has a square with + and - , the open door light has a car seen from above with an open door and so on.

The suspension system light is a little harder to decipher as it is represented by the outline of a car with two vertically placed arrows. It roughly indicates the "up and down" bike that the suspensions and shock absorbers dim with their operation.

When the shock absorber warning light comes on it indicates that there is a fault in the car's suspension system. Usually the problem is an oil or air leak (in the case of air suspension) that could cause a problem with the car's setup. Obviously, when this warning light comes on, it would be a good idea to go to the workshop to check for anomalies and prevent further damage.

What are the benefits of having car shock absorbers in good condition?

Having well-maintained shock absorbers in your car brings several benefits to your driving, see below:

  • Attenuate themovement of the suspension springs - the main function of shock absorbers is to prevent the springs from breaking in response to stresses such as potholes, bumps or obstacles in the road.
  • Improve road holding - a car's road holding also depends on the position of the weights while driving. The shock absorber prevents sudden weight shifts due to "swaying" of the centre of gravity by improving stability.
  • Ensure consistent braking - during braking, the shock absorbers prevent the sudden shift of the entire weight of the car forward, keeping the weights balanced.
  • Prevent premature tyre wear - a well-functioning shock absorber allows the tyre to grip the road evenly, avoiding the irregularities that cause premature tread wear.
  • Avoid "squatting" when accelerating - as with braking, the car's weights are shifted backwards during start-up and, without well-functioning shock absorbers, the car tends to fall heavily on the rear axle.

Symptoms of worn shock absorbers?

Shock absorbers are also subject to wear and tear and this creates the need to replace or repair them in order to continue to provide an effective suspension system. When a shock absorber has reached the point where it needs to be overhauled or replaced, it is called a "worn out shock".


So let's look at the symptoms of a worn out shock absorber:

  • The steering wheel vibrates while driving;
  • The car sways while cornering;
  • The tires are worn unevenly;
  • The effect of the crosswind is felt more than usual;
  • When braking, the car leans forward;
  • The car"sits" on the exit, leaning backwards;
  • There are oil leaks in correspondence with the shock absorbers.

In a modern, well-maintained car, symptoms of worn out shock absorbers should never occur before 100-150 thousand kilometers. If the symptoms occur on a still young car with a few miles, then there is almost certainly a factory defect (covered by warranty). If the symptoms appear in a car with hundreds of thousands of kilometers and irregular maintenance, then the problem is the natural wearof the part.

In both cases we recommend that you visit a mechanic immediately to assess the situation. The symptoms of worn out shock absorbers should not be taken lightly, as they could compromise the safe handling of the vehicle.

What problems do shock absorbers cause?

Exhaust shocks cause exactly the problems identified above as symptoms. Excessive roll , instability when cornering and "sagging" under braking are only the most obvious.

In general, if you have a good feel for driving and are often behind the wheel, you will notice that something is wrong with the car's set-up. Apart from tyre problems, including a simple puncture, the next components to consider are the shock absorbers.

If you don't know much about cars, why not get help from someone who does? Try asking a friend for their opinion after a test drive. The best way to find out if your shocks are really worn out is to trust a good mechanic anyway.

How often do you have to replace a worn out shock?

There is no fixed, super-precise time for shock replacement. Your wear and tear depends largely on your driving style and how you use your vehicle. A car that is always on the highway will have less wear on the shocks than a car that is primarily used on off-road dirt roads or just around town.

Like many car components, shock absorbers are subject to wear and it is recommended that they be replaced every 60,000 miles or 5 years.

It is essential to include a shock absorber inspection in your maintenance schedule prior to replacement. This should be done every 30,000 kilometres, which usually coincides with the life of the car.

How much does it cost to replace shock absorbers?

The cost of replacing shock absorbers depends on the number of shock absorbers to be replaced, the brand you choose as a replacement and, of course, the cost of the mechanic's labour. The cost of a single shock absorber can vary from just over 30 euros to over 400 euros for the most expensive models.

Normally the cost of replacing 4 shock absorbers ranges from 300 to 2000 euros. It is no coincidence that this is one of the maintenance operations where the choice of the spare part has the greatest impact on the cost of the repair.

What are the best car shock absorbers?

The best shock absorber is the one that works well and fulfills its function. If we then want to treat ourselves to luxury shock absorbers, as they say, only the sky is the limit.

The choice of non-standard shock absorbers in fact depends entirely on factors such as budget and usage. The modern market offers many options and it is impossible to say which one is better without knowing how to use them.

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