Strut, top mount and coil spring: what they are and when to replace them

Does the car creak when you steer, do you hear a knock over speed bumps, or is there a broken spring on the report of the APK (MOT), the compulsory Dutch vehicle inspection? Then it is usually the strut or one of the parts around it. In this article you can read what a strut, a top mount and a coil spring do, how to recognise wear and what replacing them involves.

By the team at Autobedrijf Willemsbrug, RDW-approved APK (MOT) test station since 1979 · Updated 8 November 2026

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The short answer

A strut is a shock absorber and a coil spring in one unit, which according to KYB also acts as a pivot point of the wheel suspension. On top sits the top mount, a rubber part with a bearing. According to Monroe, a hardened top mount causes vibration in the steering and noise. A broken or cracked spring is a rejection point at the APK. According to KYB, a strut cannot be repaired or refilled. We replace struts per axle, left and right together, and we tell you one price in advance, based on your registration number (kenteken).

Alignment and suspension at Autobedrijf Willemsbrug: we measure all four wheels with our own alignment equipment and test the shock absorbers on a test drive and on the lift. We only align or replace what is needed, shock absorbers per axle. If the manufacturer asks for an alignment after a repair, it is included in the quote straight away. We tell you the price in advance based on your registration number. Call +31 10 479 00 00. You bring the car and we call you when it is ready. A loan bike is free while one is available. Wheel alignment on Saturdays too, shock absorbers on Saturdays by arrangement. Our team speaks English. More about wheel alignment or shock absorber replacement

What is a strut and how is it different from a shock absorber?

A strut is a complete unit of shock absorber and coil spring that also forms part of the wheel suspension. KYB describes it like this: a separate shock absorber is a component of its own, while a strut combines the shock absorber and the coil spring and is at the same time a pivot point of the suspension. Without a separate shock absorber, the car can still be driven, according to KYB. Without the strut, the car collapses.

The spring and the shock absorber each have their own job. According to the ANWB (the Dutch motoring organisation), the spring provides the springing and carries the weight of the car. The shock absorber’s job, according to the ANWB, is to damp the up and down movement of the suspension. Without a good shock absorber, the car keeps bouncing for a long time after a speed bump. Whether your car has struts or separate shock absorbers differs per model and sometimes per axle. We can see which layout your car has from its registration number.

Part What it does
Shock absorber What it doesDamps the up and down movement, so the tyres stay on the road.
Coil spring What it doesProvides the springing and carries the weight of the car.
Strut What it doesShock absorber and spring in one unit, and at the same time a pivot point of the wheel suspension (KYB).
Top mount What it doesThe mounting at the top of the strut. According to Monroe, a rubber part with a bearing. Bilstein calls it the link between the suspension and the rest of the car.
Spring seat What it doesThe cup the spring rests in. According to the APK manual, a rusted-through spring seat must not have been repaired.
Dust boot What it doesAccording to KYB, protects the seal and the piston rod of the shock absorber against dirt and stone chips.
Bump stop What it doesAn end stop that catches the suspension at the end of its travel. According to the APK manual, it is not a helper spring.

Sources: KYB, Monroe (via Professional Motor Mechanic), Bilstein and the RDW APK manual, consulted November 2026.

How do you recognise a worn top mount?

You mainly recognise a worn top mount by noise and vibration when you steer. Monroe writes that top mounts are subject to severe wear and tear. The rubber hardens over time, and then you soon notice vibration in the steering and noise. Signs to look out for:

  • Noise when steering: for example creaking or knocking when you turn the steering wheel. Monroe names noise as a result of a hardened top mount.
  • Vibration in the steering: because the rubber has hardened, vibration from the road comes through more strongly.
  • Steering that sticks: Monroe names the risk that the steering wheel locks when it returns to the centre after a corner.

Noise when steering or over speed bumps can also come from another part of the suspension, or from a wheel bearing. That is why we first find out where the noise comes from before we replace anything. Bilstein names noise from the suspension as an important point to watch on the test drive. We take the car for a test drive, listen and then inspect the suspension on the lift. How we trace other noises is explained on our page car making a noise.

A broken spring: how do you notice it and what does the APK say?

A broken or cracked spring is a rejection point (afkeurpunt) at the APK, so the car fails. This is set out in the APK manual of the RDW, the Dutch vehicle authority (article 5.2.28). You do not hear or feel every break while driving. Bilstein names noise from the suspension as a sign, and rust and breakage as points to check during the inspection on the lift. That is why the mechanic sometimes only sees a broken spring once the car is up on the lift.

The APK manual sets these requirements for springs and the parts around them:

  • Parts of the suspension system must not have breaks or cracks, must not be seriously affected by rust and must be securely fitted.
  • A coil spring must sit properly in its seat. When the suspension hangs free, with the wheel off the ground, it must touch both places it is meant to rest on.
  • A rusted-through spring seat must not have been repaired. It must be replaced completely.
  • A missing or damaged bump stop is not a rejection point.

If one spring is broken, we replace both springs on that axle. KYB writes that springs should be replaced in pairs and that different types of spring should not be mixed on one axle. That way the car sits at the same height on the left and the right again, and it springs the same on both sides.

Replace only the shock absorber or the complete strut?

That depends on how your car is built. If your car has a separate shock absorber, we only replace the shock absorber. On a strut, we replace the shock absorber in the strut or the complete strut with its spring, depending on what is worn. Repair is not possible: according to KYB, a strut cannot be refilled or rebuilt. According to KYB, some struts do have a replaceable cartridge that holds the inner workings.

We replace shock absorbers and struts per axle, left and right together. The ANWB and manufacturers such as Monroe and Sachs advise this. Monroe explains why: a new shock absorber is stiffer than the old one on the other side. The new shock absorber then has too much work to do. No source says that all four shock absorbers must be replaced at once. We only replace the shock absorbers or struts on the axle that is worn.

Oil on the shock absorber does not automatically mean a leak. According to KYB and Sachs, a thin, even film of oil at the top of the shock absorber is normal. It lubricates the seal. If oil is clearly running down the shock absorber and oil is left on your fingers, it is leaking. At the APK, a leaking shock absorber is noted on the report as an advisory point. It only fails if it does not work properly, is not securely fitted or is missing.

Replace the top mount, dust boot and bump stop at the same time?

Manufacturers recommend replacing the top mounts as well when new shock absorbers or struts are fitted. It is not an APK requirement. ZF Aftermarket, the manufacturer of Sachs, recommends renewing the top mounts whenever the shock absorbers are replaced. KYB calls it a good idea to replace the strut mount and the dust boot at the same time, and Monroe gives the same advice. We show you the cost in advance and you decide.

For the dust boot and the bump stop, the manufacturers give these reasons:

  • Dust boot: a worn boot no longer protects the piston rod, Bilstein writes. Dirt and stone chips then damage the rod, and Monroe names oil leaking from the unit as a result.
  • Bump stop: according to Monroe, the bump stop limits roll, dive and squat of the body. A worn bump stop can lead to more wear on springs and ball joints, according to Monroe.
  • Top mount: according to KYB, a new strut mount gives a smooth steering response and less vibration.

If the strut is out anyway, it is practical to do the top mount in one go. If the top mount is still in good condition, we tell you that too. You hear the cost of each part and choose for yourself.

Does the car need an alignment after a new strut?

That depends on the car. KYB writes that struts usually need a wheel alignment after replacement, because the strut helps set the position of the wheel. Elsewhere, KYB writes that it depends on the design of the car. If the manufacturer asks for an alignment after this work, it is included in the quote straight away. We tell you one price in advance.

When we align a car, we measure the position of all four wheels and set it back to the manufacturer’s data. When an alignment is needed after a repair and when measuring is enough is explained in alignment after suspension repairs. More about how we align cars is on our page about wheel alignment in Rotterdam.

Does your car have a camera behind the windscreen or a radar in the bumper or grille? Then that system may need to be set up again after an alignment or after work on the suspension. That depends on the make and model. We do not calibrate cameras or radar ourselves. The dealer or a specialist company does that. Ask about it when you book and we will check it for your car.

How we assess and replace struts and springs

We test first and only replace what is worn, per axle. We tell you one price in advance, based on your registration number. This is how it works:

  1. Call +31 10 479 00 00 with your registration number and tell us what you notice: creaking when steering, noise over speed bumps, bouncing or a point on the APK report.
  2. We take the car for a test drive and inspect the suspension on the lift: springs, spring seats, shock absorbers, top mounts, dust boots, bump stops and the tyres.
  3. We tell you what is worn and what replacing it costs. If the manufacturer recommends replacing the top mount as well, you see that cost separately. If the manufacturer asks for an alignment after this work, that is included too.
  4. After your approval, we replace the parts per axle. If anything extra comes up during the work, we tell you first.
  5. We take the car for a test drive and call you when it is ready.

We work on all makes, including hybrid and electric cars. On Saturdays, replacing struts and shock absorbers is possible by arrangement. Everything about signs, costs and how we work is on our page about shock absorber replacement in Rotterdam.

Frequently asked questions

What is the difference between a top mount and a strut bearing?

The top mount is the mounting at the top of the strut. According to Monroe, such a kit consists of a rubber part and a bearing. That bearing is also called the strut bearing. According to KYB, the mount only contains the bearing if it is also the pivot the wheel turns on when you steer.

Can a strut be repaired or refilled?

No. According to KYB, a strut cannot be refilled or rebuilt. Some struts do have a replaceable cartridge for the inner workings. If the shock absorber is worn, we replace the shock absorber or the complete strut, per axle.

Do I need to replace both springs if only one is broken?

Yes. KYB writes that springs should be replaced in pairs and that different types of spring should not be mixed on one axle. That way the car sits at the same height on the left and the right, and it springs the same on both sides.

Does a leaking shock absorber fail the APK?

No. In the RDW APK manual, a leaking shock absorber is an advisory point. A shock absorber fails if it does not work properly, is not securely fitted or is missing. An advisory point does mean you should keep an eye on the shock absorber. Read more in shock absorbers and springs at the APK.

How long do shock absorbers and struts last?

According to the ANWB, shock absorbers last at least 8 years or 150,000 km with normal use. We do not replace them based on mileage, but on what we see on the test drive and on the lift.

How much does it cost to replace a strut?

According to the ANWB, replacing two shock absorbers on the front axle costs € 500 to € 1,000, depending on the make and type of car (consulted November 2026). A top mount or an alignment may come on top of that. We tell you your price in advance, based on your registration number, as one price.

Creaking when you steer, or a broken spring?

Call +31 10 479 00 00 with your registration number. We test first, only replace what is worn and we tell you one price in advance.

You will find us at Boterdiep 11 in Rotterdam-IJsselmonde, close to Stadion Feijenoord (De Kuip). We work by appointment. For a quick question or check you can walk in without an appointment.

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