The chassis of a car provides contemporary driving comfort and ensures safe driving of the vehicle. To ensure this under all driving conditions, numerous components of the chassis work together in a coordinated manner.

If one or more chassis parts are worn or defective, problems quickly arise. However, the symptoms that occur are not always clearly identifiable. In our guide, we explain how to recognise the most common chassis defects and when a repair is advisable.

Chassis spring broken

The suspension springs support the weight of the vehicle and at the same time ensure good ride comfort. Depending on the design of the installed chassis, the suspension spring can be a coil spring or a leaf spring. In modern cars, coil springs are mostly used, both at the front and at the rear. Here, the springs are either installed as an independent component or combined with the shock absorber to form the suspension strut.

A broken suspension spring is one of the most common problems with the car’s suspension. The symptoms that occur when the suspension spring is defective usually do not go unnoticed for long. For example, there are often unusual noises such as rattling or clattering when the suspension springs are compressed or released. Metallic clanking noises can also occur when the road surface is uneven. Often the vehicle continues to hang down on one side.

The causes of a broken suspension spring are usually overload or wear. It is not uncommon for a combination of both to lead to a defect. For example, the spring can break when driving over a kerb due to the high load. Defective suspension springs must be replaced. Used springs should only be installed if they are in good condition. Ideally, the left and right springs should always be replaced together.

Shock absorber defective

The shock absorbers of a car ensure good road holding by absorbing vibrations. They are therefore also called vibration dampers. In the area of the chassis, the shock absorber is one of the classic wear parts that break down and need to be replaced. While driving, the shock absorber works together with the suspension spring. Every time the suspension compresses or extends, the shock absorber is also subjected to load.

The shock absorber absorbs the vibrations and forces that occur during suspension and converts them into heat through friction. This effectively prevents the body from rocking and ensures safe contact between the wheels and the road. Most vehicles have one shock absorber per wheel, but in some cases there may be more than one. The shock absorbers of modern cars are usually designed as oil pressure dampers or gas pressure dampers, both containing oil.

Due to the constant load, shock absorbers are worn out after a certain mileage. The defect often manifests itself in the form of oil leaking from the shock absorbers. The driving behaviour of the car sometimes appears spongy when the shock absorbers are defective. The braking distance may also be longer and the tyres may wear more. Defective shock absorbers should therefore be replaced as soon as possible. Used shock absorbers as replacements should be visually and technically flawless.

Coupling rod damaged

The coupling rod is one of the chassis parts that are more likely to show defects due to ageing or load. This component is also called stabiliser bar, stabiliser strut or sway bar. Depending on the vehicle model, it is only found at the front in the area of the front wheel suspension or also at the rear on the rear axle. Here, the coupling rod connects the stabiliser with the suspension or the suspension strut on each side of the vehicle.

Especially when driving through bends at high speed, the coupling rods ensure a much better road holding of the vehicle. They cause the forces acting on the chassis to be transmitted from one side to the other of the vehicle via the stabiliser. Thanks to this compensation via the coupling rods and the stabiliser, the wheel on the outside of the curve dips less.

If one or more coupling rods of the chassis suspension are damaged, this becomes noticeable through various symptoms. Among other things, the car’s handling may deteriorate, with a greater tendency to lean sideways in bends. There may also be unusual noises such as rumbling or rattling from the suspension area. These signs can also occur outside of curves.

Wishbone defective

The wishbone is one of the most important parts of many chassis. Here, the wishbone connects the body with the wheel carrier. Depending on the design of the chassis, wishbones can be found at the front or rear of the vehicle. The wishbones allow the wheels to spring in and out, while still keeping the wheel suspension securely in position. While driving the car, the wishbones must primarily absorb the lateral forces acting on the chassis.

If a transverse control arm of the vehicle is damaged, various signs may indicate the defect. Especially on poor road surfaces, rumbling or rattling noises may occur. Cracking noises can also occur when the vehicle is turned sharply. A spongy driving feeling or poor steering behaviour can also occur.

Wishbones are exposed to increased loads under the vehicle. This leads to wear and rust due to moisture or road salt in winter. In the event of an accident or due to constant heavy loads on the chassis, the components can break or bend. Then the wishbones have to be replaced. Used spare parts can easily be used for this purpose. In addition to the wishbones, the corresponding wishbone bushings are often defective.

Strut bearing worn out

The strut mounts of a vehicle connect the suspension struts to the body. The component is also called a strut mount or strut support mount. There is one strut mount per strut in the top of the respective strut dome. To be able to absorb vibrations and chassis changes, strut mounts are designed to be flexible. For this purpose, they are usually made of a combination of hard rubber and metal components.

Suspension strut dome bearings can wear out with higher mileage or harden and become porous due to ageing. Then symptoms such as unstable handling or problems with the steering often appear. Unusual cracking noises may occur, as well as rumbling on uneven road surfaces. Since driving safety decreases with defective strut bearings and other chassis parts are subjected to greater stress, the parts should be replaced as soon as possible.

If the suspension struts have to be removed for the installation of new suspension springs or due to defective shock absorbers, it is a good idea to replace the strut bearings. Often the bearings are also worn at this point, and replacement is quite simple if the strut has been removed anyway. Strut bearings are not particularly expensive as a spare part. If they are installed as a used spare part, make sure that they are in perfect condition.

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