Car suspension: parts, failure symptoms, and repair costs
The suspension system essentially acts as a stabiliser for your car, minimising the impact of every bump, hole and curve in the road while maximising the friction between the tyres and road surface. A solid suspension system is designed to ensure a smoother journey and improve handling. It does so using a network of shock-absorbing components connected to the vehicle’s chassis. These components effectively absorb the energy from the tyres to stabilise the car body and frame when driving.
The car suspension can be independent or dependent. In dependent systems, the left and right wheels are connected to a single solid axle, ensuring that they remain parallel to each other. The issue with this is that when one wheel hits a bump, the whole axle feels the impact and the other wheel is affected. This makes the car more susceptible to body roll. Independent systems, on the other hand, allow the wheels to move independently of each other, meaning that jarring can be contained to one side of the axle.
What are the main suspension components?
If you want to know what to replace and how often to replace it, you’ll first need to familiarise yourself with the different car suspension parts. Here are some of the key components that you’ll need to pay attention to:
The springs play a critical role in dampening impacts from collisions or friction. They also help to increase the traction of the wheels. As the car hits a bump or dip in the road, the springs on the axle are compressed to absorb the shock. Common types include coil springs, leaf springs, and torsion bar springs.
- Shock absorbers (shocks)
As the name suggests, the rear and front shock absorber in car work alongside the springs to absorb shocks and dampen oscillations when driving. They are sometimes known as dampers because they dampen vibrations by turning kinetic energy into heat energy, which is then dissipated. This is achieved using hydraulic fluid.
- Control arms
The upper and lower suspension arm connect the car frame to steering knuckle or wheel hub assembly. Some suspension systems will only have a lower control arm. The parts move up and down as the wheels move over bumps, for example, helping to keep the tyres in contact with the road and keeping the vehicle stable when turning.
- Ball joints
They’re normally located at the front of the car and help it to make left or right turns, linking the control arms and the steering knuckle together. They also enable the control arms to move up and down.
Signs your car suspension needs to be repaired
- Squatting, diving or rolling
If the shocks are worn or faulty, you may notice that the car dives forward ‘nose-first’ when you apply the brakes. The car may also roll to the side when cornering or lean backwards during acceleration. If you’ve noticed that the vehicle sits lower than usual, there could also be a problem with the springs.
- Drifting or pulling to one side when driving
A common sign of a worn suspension system is that your car drifts or pulls to one side when making turns or driving forward. You’ll need to check the shocks, ball joints and control arms for signs of damage. When these components are worn or broken, it often affects the wheel alignment.
- A bumpy ride
If the suspension isn’t doing its job properly, there’s a good chance you’ll feel every bump, crack and hole in the road. Worn shock absorbers or struts are the most common culprit. You can check the suspension by doing a bounce test. This is where you push down on the bonnet with all of your body weight and then release it. Count the number of times the vehicle bounces. If it bounces more than three times, you should get the parts checked and replaced.
- Oily shocks
If you take a quick look at the shock absorbers under the vehicles, you may notice that they look like they’re covered in oil or grease. This usually means that they are leaking fluid. If they lose too much fluid, they will be ineffective.
- Steering problems
When your suspension is acting up, it can often cause steering difficulties, particularly when driving at low speeds. This is because the two systems are deeply interconnected. It is best to get the vehicle diagnosed and fixed by a professional in this case.
- Uneven tyre wear
This is often referred to as tyre ‘cupping’. When the suspension is putting uneven amounts of pressure on the tyres due to damaged or worn components, you may find that there are random bald spots on the tread. These spots usually measure around 3 to 4 inches.
How much does it cost to repair or replace the car suspension system?
This will depend on what exactly the problem is and how it can be fixed. For example, the average price for replacing the front shock absorbers in the UK is around £312, whereas if you’re looking to get a new suspension arm ball joint for your car, it could cost you between £60 and £150. Prices will also depend on the make and model of the vehicle.
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