Have you ever heard a strange grinding noise when braking but were surprised to find that your brake pads were actually fine? This is a common issue that plagues many vehicle owners and can be difficult to diagnose.
In this guide, I’ll discuss all possible causes of grinding noise when braking even when you find that the brake pads are fine.
So, why grinding noise from braking but pads are fine? A groaning or grinding noise when braking, despite fine brake pads, could be due to a warped brake rotor creating uneven contact, worn-out wheel bearings, built-up dirt or debris on the brakes, low-quality aftermarket brake pads not aligning with manufacturer specifications, or a sticking or broken brake caliper. Such issues might stem from heat, regular wear and tear, or improper materials and sizes.
Also Read: Groaning noise when braking at low speed
Table of Contents
Causes Of Grinding Noise When Braking But Pads Are Fine
Here are some of the most possible causes of grinding or groaning noise when braking but pads are fine:
1. Dirt Between Brake Pads and Rotor
When the brake pads meet the brake rotor, the contact between the two parts creates friction, which produces the braking power.
But, when dirt and grime get between the brake pads and the brake rotor, it can cause the two parts to rub together, resulting in a grinding noise.
Dirt can get between the brake pad and rotor in a variety of ways. In some cases, it can be from riding in areas with a lot of gravel, mud, and dirt.
When the brakes are applied, the material can get stuck between the pad and the rotor. Other times, it can be from improper brake pad installation or from contamination of brake fluid.
Another common cause of dirt between the brake pads and rotors is mud. If your car has been through a deep puddle, the muddy water can get between the pads and rotors and cause the same grinding noise.
How to fix?
If there is just dirt between the brake pads and the rotor, all you need to do is to clean the brake rotor. The best way to clean brake rotors is to use rubbing alcohol on a towel. You can also use CRC brake cleaner to clean the brake rotor.
2. Wear Tab Is Scraping The Rotor
Brake pads are composed of three distinct components: a metal backing plate, a pad of friction material, and a wear indicator.
The metal backing plate acts as a stabilizer, securing the pad to the brake caliper, while the pad of friction material generates the friction required to decelerate or stop a vehicle.
Grinding noise when braking usually indicates metal-on-metal contact. If you’re observing that brake pads are fine, the chances are that they have evenly worn out and become thinner to a certain level that the backing plate of the brake pads is scraping. When this happens, it indicates that the brake pads need to be replaced.
How to fix?
Brake pads should be replaced when their thickness becomes less than the thickness of the backing plate. The minimum thickness of wear pads is around 3 to 4mm. After that, the brake pads should be replaced.
3. Scoring or Corrosion on the Brake Rotor
The brake rotors are the discs on the wheels that are connected to the axle and allow your brakes to function properly. There are a few possibilities that could explain why your brake rotors are making a grinding noise, even if the brake pads are still in good condition.
One of the most common causes of grinding noises in the brake rotors is scoring. Scoring is when the smooth surface of the rotor becomes rough and uneven due to wear and tear.
This can cause a grinding noise when the brake pads make contact with the rotor. If the scoring is bad enough, it can cause your brakes to be less effective, as well as create a grinding noise.
Another potential cause of grinding noises in the brake rotors is rust and corrosion. Rust can form on the rotors when they come into contact with water or moisture, and when the brake pads make contact with the rotor, it can create a grinding noise.
Furthermore, if the rust buildup is significant, the brake pads can start wearing down quicker, making it difficult for the car to come to a complete stop.
Warping is another potential issue with the brake rotors that can cause grinding noises when braking.
Warping occurs when the rotor is subjected to extreme temperatures, such as during hard braking or driving in hot weather.
This causes the rotor to become uneven, which can result in a grinding noise when the brake pads make contact with the rotor.
How to fix?
If there is just rust on the brake disc, try to remove it with the wire brush. A wire brush or steel wool can only be used for light to medium rust or deposits.
For stubborn rust or light scoring marks, you can try using 120-grit sandpaper. Don’t forget to clean the brake rotor with rubbing alcohol or CRC brake cleaner. Another tip to remove dust from the brake rotor is to soak it in vinegar for some time.
Furthermore, you can also use Scotchbrite pad and rubbing alchohol to clean the brake rotors.
To check if there are grooves in the rotor due to scoring, scrape your fingernail down each face of the rotor. If it goes without catching in a groove, the brake rotor is fine. If there is a grove deep enough to catch your fingernail, the brake rotor needs to be replaced.
Warped rotors do not show visible signs of damage. You’ll feel vibrations in the steering wheel while driving or wobbling brake pedal, the brake rotor is most likely warped.
4. Brake Pads Are Glazed
Glazed brake pads are the most common cause of grinding noise when you brake, but it doesn’t necessarily mean that your pads are bad.
Glazing occurs when the temperature exceeds the limiting temperature of the friction material of brake pads.
Glazing is caused by the brake pad material becoming overheated, which can happen if the brakes are used heavily or for extended periods of time.
Brake pads have an optimal operating temperature range, depending on the material.
When this range is exceeded, the binders and materials in the pad start to melt and glaze over. This process reduces the friction material’s ability to slow down the vehicle and causes the sound of grinding when you brake.
How to spot?
Glazed brake pads have a shiny and glossy appearance on the area where they contact with the brake rotor.
Furthermore, the surface of brake pads may also exhibit small cracks. In addition, you’ll have a quite hard brake pedal that won’t stop your vehicle when you apply brakes.
How to fix?
If brake pads are lightly glazed, first wet them with isopropyl alcohol and sand them with 280 to 320 grit sandpaper on a granite stone or concrete slab. You can also try scuffing brake pads on concrete sidewalks or asphalt surfaces to deglaze them.
However, I would advise you to just get new brake pads instead of going through this headache. This is because the brake rotor is quite expensive, and glazed brake pads can damage the brake rotor, which will become quite expensive to fix in the long run.
5. Brake Pads and Rotors Are Not Bedded Properly
Bedding is the process of preparing the brake pads and rotors for use. This process involves applying pressure and heat to the brake pads and rotors to ensure that they form a flat, even surface. When done correctly, bedding helps ensure the brakes will perform smoothly and efficiently.
When bedding is not done correctly, the brake pads and rotors are not allowed to mate perfectly. This can cause the brake pads to wear unevenly, which can cause a grinding noise when the brakes are applied.
Whether you have got new brake pads and rotors or you have scuffed and cleaned old rotors and pads, it is essential to bed them in.
Bedding in the brakes can be done by applying the brakes lightly but firmly several times in a row.
How to bed in the brakes?
To bed the brakes, you will need to lightly press on the brakes at a low speed and then come to a complete stop. This process should be repeated several times, increasing speed each time. After a few cycles, you will begin to feel the brakes become smoother and quieter.
So, drive the vehicle at a speed of 60mph and slow it down to 5mph speed with fairly heavy braking without coming to stop.
This will raise the temperature of brake components sufficient for the bedding of brakes. Make sure that you do not press the brakes too hard as it will activate ABS. Repeat this process 10 times.
6. Noise Of Brake Pad Material
Brake pads come in the following materials:
Ceramic brake pads are very quiet compared to other brake pad materials. Moreover, ceramic brake pads produce very little dust. However, ceramic brake pads are not suitable for high-performance or heavy towing vehicles. This is because ceramic brake pads cannot sustain the high heat levels that those vehicles require.
When the braking system is subjected to high heat due to harsh braking, ceramic brake pads can become glazed and damage the brake rotor. As a result, your vehicle will produce grinding noises when braking.
On the other hand, semi-metallic brake pads are not as durable as ceramic brake pads but are more heat-resistant and can handle a wide range of temperatures.
Semi-metallic brake pads have increased stopping power that can handle the higher pressure required by performance vehicles or heavy-towing vehicles.
However, semi-brake pads are noisiest compared to the other brake materials and produce most brake dust.
Furthermore, semi-metallic brake pads are more harsh on brake rotors. Due to this reason, semi-metallic brake pads are more prone to squealing and grinding noises.
7. Aftermarket Brake Pads With Improper Size
When it comes to aftermarket brake pads, you might be tempted to go for the cheapest option. However, it’s important to stay away from inferior quality parts, as they might not fit correctly, wear-out faster and can also damage the expensive brake rotor of your vehicle.
When you install aftermarket brake pads that are not the correct size, you can experience several problems. The first, and most obvious, is that the grinding noise will occur when you brake. This is due to the improper installation of the brake pads, as they may not fit correctly in their slots or may not be the right thickness to handle the pressure.
The size and shape of aftermarket brake pads are important for a vehicle’s performance because they affect the amount of force needed to lock the wheel. If the brake pads are too small, they won’t wear down properly as you drive and apply the brakes.
On the other hand, if the brake pads are too large, they may not fit into the caliper slot. This can cause excessive wear on the pads and rotors, leading to decreased braking performance and increased risk of damage.
8. Sticky Brake Caliper Pins
Caliper pins are small metal pins that connect the brake pads to the caliper. They’re made of metal and are often coated in a lubricant, such as grease or oil. This lubricant helps the pins move easily without any binding or sticking.
If you have a sticking brake caliper, it will be hotter than calipers on other wheels.
When the caliper pins become stuck, they stop the brake pads from being able to move freely, which is what causes the grinding noise. The brake pads can’t be pushed against the rotor properly, and so the sound of metal grinding on metal is the result.
Caliper pins can suffer from sticky issues due to a range of causes. Corrosion from road salt and moisture is one of the most frequent culprits. Over time, this can cause a build-up of residue on the pins, which impedes their ability to move easily when the brakes are engaged.
Another common cause of sticky caliper pins is contamination. If you closely look at caliper pins, they are protected by the rubber boot. If rubber boot cracks, the grease will leak out and dirt will enter. If the caliper pins become contaminated by oil, dirt, or other substances, they can become sticky and not move freely.
9. Corroded or Loose Bolts of Brake Calipers
The brake calipers are connected to the wheels by a set of bolts, which can corrode or become loose over time.
Corroded or loose bolts can occur for several reasons. The most common is salt, dirt, and other environmental factors. They can cause the bolts to deteriorate, making them less stable. If the bolts become too loose, it can lead to the caliper rattling against the brake pad, causing a grinding noise.
If you suspect that your brake caliper bolts are corroded or loose, you can do a visual inspection.
The only way to fix the problem is to replace the corroded bolts. It’s also important to make sure that the bolts are properly tightened according to the specifications (you should follow torque values of the bolts).
10. Bent Backing Plate
The backing plate or dust shield of brake calipers is usually bent inward on the forward edge to funnel air onto rotors and help cool brakes.
The backing plate is made up of a metal material and is mounted behind the brake calipers. It helps to keep dirt, water, and other debris away from the brake pads and rotors.
Without this plate, the brake pads and rotors would be exposed to the elements and could become damaged over time.
If the backing plate is bent too much, it will rub against the brake rotor and cause grinding noises.
In order to determine if the dust shield is bent, you need to remove the caliper and inspect the shield. A bent shield will be noticeably out of shape, which is easy to spot.
If the backing plate appears to be bent or distorted, it can be tested by pushing the top and bottom out through the wheel with a flathead screwdriver without taking it off first.
11. Damaged Wheel Bearing
Wheel bearings are metal components located inside the hub of the wheel. They are made up of a series of balls or rollers that fit into an inner and outer race. A wheel bearing supports and helps keep the wheel steady while it moves around the axle.
Wheel bearings can get damaged due to wear and tear over time, or due to an impact or shock to the wheel assembly. This can cause the wheel bearing to become misaligned or worn out, resulting in a grinding noise when the brakes are applied.
The grinding noise is produced because steel balls of wheel bearings rub with each other due to misalignment.
How to spot?
When the wheel bearing is damaged, you may also notice that the car pulls to one side when braking, or that the steering wheel vibrates when driving at high speeds.
Final Thoughts About Grinding Noise When Braking But Pads Are Fine
In summary, grinding brakes despite good pads could arise from debris buildup, worn rotor tabs, rotor rust/scoring, glazing, improper bedding, noisy pad materials, mismatched parts, sticky calipers, loose bolts, bent shields or bad wheel bearings.
Inspecting pads, rotors, calipers, wheels, shields and bearings can identify issues. Cleaning parts, replacing damaged components, bedding brakes properly and using quality materials eliminates noises.
Preventative maintenance checks brake health. Addressing grinding sounds promptly avoids safety risks and further brake damage.