Suspension systems are crucial to keep your car in good working condition. They prevent damages to other important parts while ensuring that you enjoy a smooth and nice ride. Over time, water, salt, rust, and potholes will put a strain on the various components, ultimately leading to a failure. But like with most other drivetrain parts, wear can usually be felt and heard long before something breaks and brings your car to a halt. So what are the noises and symptoms of a broken suspension system and how can you fix it before you need to have your car towed to the nearest repair shop?
Table of Contents
How suspension systems work
The suspension system connects the wheels to your vehicle. It is designed to counteract gravity, propulsion, and inertia that are applied to your vehicle as you accelerate, slow down or stop in order to keep all four wheels in contact with the road.
The tires are the most important and visible parts of the system. They transfer the power of the engine to the ground when your vehicle moves and stop this movement when brakes are applied.
When driving on a bumpy road, bumps are absorbed by the combined work of a shock absorber, or a suspension strut, and a coil spring. Contrary to popular belief, it’s actually the spring that manages the abuses of the road by allowing the wheel to go up and down to stay in contact with the pavement at all time, not the shock. In return, the shock absorbers ‘absorb’ the movements of the suspension to prevent it from bouncing forever.
But a suspension system is more than just shocks and springs. The suspension arms, ball joints, stabilizer bar, and links are all working together to provide the safest and quietest ride possible.
Until things break…
Common noises and common fixes
Suspension noises come in all shapes and sizes (figuratively, of course) but some are simply more common than others. Some are so typical to a specific part that most experienced mechanics will have a good idea of where to check for the cause to problems only by performing a road test. Raising the car on a hoist is still mandatory to confirm and locate the problem without doubts but it sure helps to know where to look for before even taking the tools out.
Knocking when slowing down or cornering
When slowing down or cornering, the weight balance of the car switches to the front and the added load often causes noises to sound louder than usual. When trying to find the source of a specific noise, always try to imagine what specific part is in use when the noise is heard. When the load is put on the nose of the vehicle, the main part in use is the shock absorber.
A deep knock-knock sound usually means that the shock itself is the problem. Check for oil leaks before anything else. A leaking shock absorber will lose its stiffness and will produce a typical dull “thump” sound.
A knocking sound when braking, especially when the car is almost completely stopped can also be caused be sticking rear brake linings. To isolate the problem easily, try pulling the handbrake a bit so the linings slightly drag inside the brake drums while driving on a bump. The knocking sound should stop if it’s the linings are problematic and should still be heard if it something else.
Knocking on potholes
A knocking sound, while driving at a constant pace, can be caused by pretty much any loose suspension part. The most common causes are:
- Dull shock absorbers;
- Loose stabilizer bar bushings;
- Loose stabilizer links;
- Broken shock mounts.
Sound is really difficult to translate into words but, all these components will make a different sound when failing. A soft low-pitched knock when the car hits a pothole is usually related to a shock problem. A constant repetitive fast knock on every little bump on the road, especially at high speed, is probably more related to a shock mount.
Shock absorbers serve as a link between the chassis and the wheels. It’s what’s holding everything together. They influence overall ride comfort, steering and, above all, handling.
In case of defective shock absorbers, for example, the body of the vehicle will jump and wobble excessively and the tires will have a hard time staying in contact with the pavement, which will obviously decrease the effectiveness of the brake and steering system. If the tires are not touching the ground, your car can’t steer or brake.
Simple as that.
Links and stabilizer bushings, on the other hand, will be heard mostly at slow speed. Depending on the make and model of your car, loose links may be a pretty common problem or not. After almost 15 years as an auto mechanic, I’m still not sure what makes them to become loose that quickly but, on some car models, links need to be replaced all the time. Hyundais and most Japanese cars, exception made of Toyotas, are especially prone to this. Don’t know why. It still a fact. Don’t worry, it’s really not the worst situation on this list since stabilizer links are pretty inexpensive, quick and easy to replace and have little to no real impact on how the car is driving.
Still annoying tho…
Knocking on small cracks and bumps
When you start hearing small knocks coming either from the front or the rear wheels when driving over small cracks, holes, and bumps on the road, you should definitely look towards the stabilizer links.
To locate and diagnose loose links, begin by raising the car on a hoist or floor jack. Take the lower part of the link firmly and try to shake it up and down. If there’s a loose, you’ll hear it knocking in your hand. Watch out for false diagnosis when doing this because loose stabilizer bushings will make almost the same sound as loose links. When in doubt, put one hand on the link and one on the bushing while shaking. You should be able to feel it in only one hand, letting you know which one needs to be replaced.
Ball joints can also knock when they are loose and these are becoming more and more frequent every year since newer cars can now be equipped with up to 4 ball joints on each wheel. That’s 16 ball joints in total!
Diagnosis is pretty much the same as for links. Jack the car and try to shake your wheel up and down, and side to side. Putting your hand on the ball joint will help you differentiate a ball joint problem from a tie rod end problem.
Be aware that the rupture of a ball joint can cause the detachment of the wheel! Never postpone fixing a loose ball joint or you may regret it. Links can wait but ball joints need to be replaced as soon as a loose is detected.
Knocking when turning the steering wheel
If by turning the steering wheel in almost any situation but especially when parked, you can hear a grinding noise, you probably have a strut mount bearing problem.
Macpherson shocks pivot at the same time as the steering wheel is turning and thus, require to be mounted on bearings. In most case, these bearings aren’t sealed tight and water will eventually cause them to rust in the long run. When it happens, a slight grinding noise can be heard. It could also be a distinctive and repetitive “klonk-klonk-klonk” depending on the type of bearing and how it’s designed. Some grind, some klonk but they will definitely make some sound every time the steering wheel is turned.
Sometimes, the steering wheel will also become harder to turn and you’ll be able to feel it’s not moving freely anymore. Watch out not to mistake a stuck steering column joint for a busted shock mount bearing. Just like for diseases, the same symptom can have multiple probable causes. Always confirm your diagnosis by performing the appropriate tests to prevent the replacement of parts in correct working condition.
Rusty door hinge noises
Rusty door hinges noises were once really common, especially on old Honda Civics made in the ‘90s. It doesn’t happen as much as it used to but it’s still a thing.
The distinctive squeak will be heard almost every time the problematic wheel is moving. When turning the steering wheel, when hitting the gas and brake pedals, when driving on potholes and bumps. Super annoying.
This condition is often caused by rust buildup inside a ball joint. And since ball joints are basically balls allowing the wheels to be turned in every direction, the door hinge noise will be heard when the wheel turns in ANY direction. Up, down, forward, backward, and even from side to side.
Other causes for a horror movie rusty door hinge noise are:
- leaking shock absorbers;
- oxidation of the coil springs;
- missing or defective coil spring seats;
- a deformation of the damper rod.
Luckily. all of these will usually cause the noise to be heard in only one direction, most frequently when moving up and down.
Metal-to-metal noise on bumps
A loud metal-to-metal noise when driving over potholes and bumps will usually indicate a defective control arm bushing. With time, control arm bushings tend to dry out and crack and the control arm will end up sitting on the subframe of the vehicle. Depending on the position of the components and the severity of the condition, it will cause the control arm to either make an intermittent grinding metal sound or a huge “bang” every time the wheel goes up and down.
A broken or loose control arm bushing will usually have a negative effect on the steering system and the wheels may also start shaking at high speed.
Coil springs can also cause a metal-to-metal noise when they break or if they are positioned incorrectly when replaced. Less common than broken bushings, broken coil springs are still a pretty common thing on older vehicles and especially where winter conditions are harsh and ice abrasives are used a lot.
In the end
The suspension system makes up a large part of the moving components on your vehicle. They have to endure a huge amount of stress every time you drive your car and, consequently, will require more maintenance and risk being faulty more often than most other systems. Lucky for you, suspension parts are most of the time pretty easy to replace and cheaper than most other systems to work on. And, hopefully, with the help of this post, you’ll be able to find the problems related to suspension noises and fix them without any hassle and save tons of money at the same time. What’s not to like?