Do you hear a grinding or scraping noise coming from your car’s undercarriage while driving? Not only is the sound annoying, but it can also indicate a problem that compromises overall vehicle safety. You’ll want to find out what’s causing the noise so that you can fix the issue right away.
Unfortunately, there isn’t a one-size-fits-all answer as to why you might be hearing a grinding noise from your car’s undercarriage while driving. To determine the root cause of the concern, you (or your mechanic) will need to do some troubleshooting.
Once you start to dig in, there’s a good chance you’ll find the noise coming from one of the following sources.
Brake pads and shoes help create the friction needed to bring your car to a stop. In a disc brake system, the pads are pressed against a disc-shaped rotor to halt the vehicle. When a drum brake system is used, shoes are pushed outward against a circular drum to create the same effect.
Severely worn brake pads or shoes can create a grinding noise while driving. The problem happens when the brakes are worn down to the backing plates (or wear indicators), allowing for constant contact with the drum or rotor.
When a vehicle sits for an extended period, the surface of the rotors will accumulate rust. The rust can cause the brakes to make a grinding noise whenever the car is in motion. Usually, the noise goes away quickly, as the rust gets cleared off by the brake pads each time the brakes are applied.
Drum and disc brake systems both use backing plates. The backing plates are located behind the brakes to shield the braking components from water and debris. In a drum brake system, each backing plate also provides a mounting point for the brake shoes and related components.
Because backing plates are made of thin metal, they can easily get bent. When that happens, the backing plate then contacts the rotor (in a disc brake system), creating a grinding noise. It’s also possible for the backing plate to contact the drum in a drum brake system, though the issue is far less common.
Your car has a wheel bearing (or axle bearing) at each wheel. Each wheel bearing allows one of the wheels to rotate with minimal friction. The wheel bearings also help support the weight of the vehicle.
When a wheel bearing starts to go bad, it often makes a growling or humming noise when the vehicle is in motion. If the faulty bearing is left unchecked, it will usually begin to make a grinding sound.
You’ll notice that the frequency of the sound corresponds to the rotation of the tires. Also, the sound will increase with vehicle speed (though it may go away at a certain point) and may get louder when turning in one direction or the other.
A grinding noise can indicate a safety concern, such as worn-out brakes or a bad wheel bearing. As such, you’ll want to address the problem right away to ensure your vehicle remains safe and dependable.
Because a variety of problems can cause a grinding noise while driving, you (or your mechanic) will need to do some troubleshooting to get to the bottom of the problem.
Below, you’ll find a few steps that you can take to help diagnose the concern. If you’re unsure of where the noise is coming from, you might need to repeat each step at all four corners of the vehicle.
Once you find the cause of the noise, you can perform the necessary repairs to fix the problem.
As mentioned, the grinding noise you hear when driving could stem from various issues within the braking system. You must identify and repair or replace the part that’s causing the noises before it could give way to bigger issues and heftier bills at the repair shop. Lucky for you, CarParts.com has you covered.
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Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.
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do you have a guide on how to replace 2010 mazda 3s rear rotors and pads?
I have done mechanic work before but it was drum brakes and the wheel cylinder honing, etc.
Would these be easier to replace.
I am retired and do not need the car much, so it could be down for a while if needed.
What would be the hardest part (getting old rotors off?) do you still need to bleed the brakes afterword?
Hello Peter,
Replacing disc brake pads is usually much easier than replacing drum brake shoes. However, on your vehicle, you will need a special tool to turn the caliper piston back in its bore before installing the new pads. There is no need to bleed the brakes as long as you do not disconnect the brake lines or allow air to enter the brake system in any other way.
We do not have a guide for replacing the pads and rotors on your vehicle. You might be able to find something helpful on YouTub. If not, we suggest consulting a repair manual or repair database, as outlined in this article: https://www.carparts.com/blog/why-you-should-always-consult-a-repair-manual/
I feel a bad noise when I'm driving but when I apply breaks noise dissapear it sounds very bad but I don't think is a wheel bearing at all
Hello,
What is the year, make, and model of your vehicle and what does the noise sound like?
I have a grinding noise coming from my front left wheel. It’s there when I accelerate, getting louder as speed increases. A little louder when turning, and gets the loudest when i’m braking. I’ve done a lot of research to pinpoint the issue before paying for service, but i’m stuck between bad rotors/brake pads & bad wheel bearing. It’s an 09 Chevy Impala LTZ.