People, who drive cars, often encounter squeaking, grinding, and scraping sounds. That may result from vibration when braking their cars, especially brake noise at low speed. To get the picture full and clear, you need to understand the braking system and how brakes work. Thus, we can know why these sounds are happening and how to prevent them in the future.
The working principle of braking is the friction between the braking pad and rotors attached to the wheels to decrease the speed until full stop. So, when you hit the brake paddle, the hydraulic oil presses the brake pad against the rotors to apply friction and stops the car. In this braking process, you may hear noise when you’re braking at Low speed. Usually, this may point to a defect in one of the braking elements.
What are the reasons for Noise when braking at low speed?
When you hear a strange noise when braking at a low speed, you need to be aware. These sounds can be on alert for danger. It’s safe to have a soundcheck and find out what are the sources of these noises. In this section, we’ll be discussing the main reasons for such noises.
Worn-out braking pads: One of many reasons for having strange sounds while braking is having worn-out braking pads. The brake pads are usually manufactured from a mixture of graphite, iron, and copper. These things are Bonded together to form the brake pad. When you use the brakes, the brake pad keeps wearing out until the outer metal cover touches the rotors. At that time you will start hearing creaking noise when braking at a low speed. So, if your braking pads used for a long time or have been worn out, go and change them immediately. Or else, you can do harm to other braking elements or they can get damaged.
Cheap/low quality breaking pads: As we talked about before that the brake pads are made from a mixture of different elements to make the pad bond, in order to produce the best braking pad, the manufacturers put these elements in a certain ratio to ensure the best braking effect and to stop any noise while braking. But the cheap aftermarket braking pads are never made with this accuracy in selecting substances of the pad. They always try to decrease the price which means quality decreases. Not only do they produce noisy sounds but also they rub and scrape the surface of the rotors. So, if you’re planning to replace your braking pads, you’ve to choose the original ones only.
Worn-out rotor disks: Wearing rotor disks may happen from braking using worn-out braking pads or using a cheap/low-quality braking pad that scratches the surface of the rotors. So, after a while, the surface of your rotors will never stay flat as it is. Another reason for deflection of the surface of the rotors is washing your car and exposing the rotors to cold water while it is still hot. This will lead to surface deflection and you’ll hear sounds while braking as well as feel irregular vibrations when you press the brake pedal.
Solid items between rotor and pad: If you’re using your car in a dusty environment, it is normal for braking parts to catch dust, dirt, and grime. Besides, very tiny rocks and sands can get in between the braking pad and the rotor. These items will cause grinding noise even if you’re not using the brakes.
Parking the car for too long: Leaving your car in the garage for too long in bad weather like air full of water vapor can form a rust layer on the rotors. This may also start corrosion on the rotors and this can spread to other braking system elements.
Unlubricated caliper screws: This is also another cause of hearing scraping noise when braking due to lack of lubrication on the caliper screws and bolts. If this happens to you then you have to ask your mechanic to change them.
Broken shims: Brake pad shims are basically thin rubber or metal adhesive that fits between the brake caliper and the brake pad to fill the small gaps that may lead to bad noise. A worn-out shim will make a metal-to-metal contact creating a grinding sound. And probably you will hear a knocking noise when braking at low speeds Make sure you replace them when making any brake job.
Types of the noise of Braking Systems
In this section, we’re going to differentiate between the different braking noises. And we’ll know how to diagnose the defect from the sound itself. Here we have three types of braking noise and those are grinding, squeaking, and squealing
Grinding noise: This should be your wake-up call. If you hear the grinding noise from your car, you have to stop immediately. Because this means that the brake pad got used up and now you are making metal-to-metal contact between the caliper and the rotor.
Squeaking: If you hear that very annoying squeaking or scraping sound when you hit the brake pedal, this means that the brake pad that is installed in your car is one of low quality. Because it might contain a large metal flake in the mixture of it. So, when it drags along the rotor, you’ll hear this sound.
So, the best way to get away from this type of noise is to choose a high-quality braking pad. Also if you hear a squeaking or scraping noise while you’re stopping the car using the brake, this means that the rotor is being hit by the brake wear indicator and it’s making this noise. This thing named the wear indicator of the brake is a metal tab attached to the pad of the brake when the brake pads are worn out and need to be replaced. This indicator starts dragging to the rotor to let you know that you need to change the pads.
Squealing: This happens when you park your car outdoor or wet area. What happens is that the rotors build up a layer of rust on the rotor surface. This can cause a thumping or squealing sound when you start moving your car. This sound might have vanished away after many breaks as this rust layer will be stroked out.
How to fix the brake noise problems
So, we’ve learned more about the noise we may hear from our braking system and also how to differentiate between them. Besides, we got exposed to the reason why these sounds might happen. In this section, we’ll learn how to perform some checks to know where the defective part is.
Find Loose parts: The first step is to disassemble the front wheels of the car. Then you will perform a simple check by trying to wiggle the braking calipers, pads and rotor, and other brake components. All these parts should not be moved or wiggled just by hand. If you can vibrate it with your hands, then there are a few missing, damaged, or loose clips and bolts. You need to fix those immediately. This may lead to vibrating and noisy braking.
Apply Dampening Paste: Excessive vibration from braking parts always led to lousy noises when braking. So, after taking care of missing bolts and damaged shims or clips, you may have to apply dampening paste which is a water-based compound that is highly effective in reducing vibrations and noises coming from braking parts.
Apply a thin layer of this substance on the back of the braking pad on the metal part of it between the braking pad and the caliper piston. Give the paste plenty of time to dry (2 or 3 hours or until it is completely dry) before reassembling the brake unit. It will become sticky and darker when it is dry.
Inspect Brake pads or Brake Shoes: Check the brake pads for wearing out or replacement. This is the main problem that many drivers face when they’re using their cars. Many braking pads have a wearing indicator that’s designed to make noise when it’s worn out. Aftermarket brake pads vary in size. This will cause a brake pad to wear unevenly. This causes the brake pad to ride the edge of the rotor causing rational braking noise so you may hear grinding noise when braking but pads are fine.
In this case, you can sand the lip down and make it even this will increase brake pad life and eliminate the noise. If you find out that you need to replace the brake pad, try to find a good one. New brake pads can make a grinding noise too until the brake pads are in the shape of the rotor’s surface.
Check brake rotor: The last check you can perform is checking the braking rotors. While you are using your vehicle and changing braking pads, the brake rotors may be affected by all of this. An irregular brake rotor causes the brake pad to jump and wiggle.
You have to have a very smooth rotor surface. So, if the rotor wear is not too deep then you may have to get your rotors machined in order to make the surface of the rotor smooth. Always check the rotor’s thickness before machining because this may affect the safety of braking. But if the wear is excessive, or the entire rotor is distorted or doesn’t have a secure thickness, you have to replace the rotors as soon as possible.
Extra check: It is always recommended to check the brake oil and the brake lines after any maintenance in the braking system. You have to check the level of it. If it is below the marked level then you need to fill it up with the proper oil recommended by the manufacturer Dot 3, Dot 4, and Dot 5.
Also, check the brake fluid color. It must be clear and bright. If it’s brown, then you have to change it. You may check for leakage in the brake line and if you find any, change it as soon as possible.
Brake Noise Faqs
Why does my car make a creaking noise when I brake?
Ans: This may be because the shims, clips, and bolts are not well fitted, and the brake unit wiggling during car moving. So, in order to solve this creaking sound, you may have to check that all of the above parts are well-fitted and strongly connected to each other. Otherwise, you have to replace the defective one.
What do bad brake pads sound like?
Ans: Brake pads always make a squealing or screeching noise that sounds like the friction of the chalk on the board. This sound means the wear indicator is dragging into the rotor or that the braking pads are made from a low-quality mixture and there is a metal flake in the brake pad bond dragging into the rotor.
Why does my car make noises when I brake?
Ans: There are many possibilities for brakes making noise when stopping. Some of it is related to the worn-out braking pad and also the usage of low-quality marked brake pads. There is another reason that lies behind the clips or shims not well installed or defective. So, vibration happens and it leads to high braking noise. Another reason is that the braking rotors have an uneven surface. This may lead to noise when braking. All you have to do is inspect the reason behind the sound and early detection of it may prevent you from a big danger.
How do you know if you need new brake discs?
Ans: Run-on a brake disc inspection. Check the discs by looking at the surface of the brake disc and notice how smooth is it or if it has deep grooves or not. Besides, try listening and feeling the braking effect if there are any squealing sounds while braking or does the car has vibrations when braking or not. If all checks became positive this means you need new brake discs.
Finally, braking noise can be an early alert for a serious problem. In this guide, we got to know the causes and types of braking noise problems that may help you to protect yourself from the causes and fast-acting. If you felt that there is any fault regarding the braking system then self-diagnose the defect and try to fix the defect yourself. But if you felt confused about the failure in your car just go ahead to the nearest authorized workshop and get the fix done.