Bad Brake Pads: Symptoms, Appearance, Sound & More
What are Brake Pads
Brake pads are a key component in a vehicle’s braking system. They are located in the brake caliper and press against the brake rotor to create friction and stop the wheels from turning. When the brakes are applied, hydraulic pressure in the brake lines pushes the brake pads against the rotor. The friction between the pads and rotor slows the wheels down, allowing the driver to control the speed of the vehicle and bring it to a stop.
Brake pads are typically made up of a metal backing plate bonded to a friction material such as semi-metallic, ceramic, or organic compounds. The friction material grips the surface of the rotor when the brakes are applied. As the pads press against the spinning rotor, kinetic energy is converted to heat energy through friction, slowing the vehicle down.
Over time, the constant friction wears down the brake pad material. The pads must be replaced periodically to ensure the braking system continues functioning properly. Worn out pads with little friction material left can result in poor braking performance. Replacing brake pads regularly is crucial for safe driving.
According to this video, brake pads work in conjunction with the rotor and caliper to provide the friction necessary to stop a moving vehicle. When the brake pedal is pressed, brake fluid flows into the caliper, pushing the brake pads against the rotor. This clamping force slows the spinning rotor and wheels, bringing the vehicle to a stop.
Signs of Worn Brake Pads
There are several signs that indicate your brake pads are wearing down and need to be replaced soon:
Indicator Tabs – Most brake pads have built-in tabs that will scrape against the rotor when the pad material gets low. This produces a screeching noise when you apply the brakes that alerts you that the pads are nearly worn down to the minimum thickness.
Uneven Wear – If you notice the inside or outside pad on a caliper is wearing faster than the rest, this indicates a mechanical issue. Common causes are a stuck caliper, misalignment, or worn suspension components. Uneven wear will reduce the pad’s lifespan and cause handling issues.
Glazing/Loss of Friction – Over time the pads will become smooth and shiny from the heat cycles of normal braking. This glazing prevents them from gripping the rotors effectively. You’ll notice an increase in braking distance as the worn pads slide instead of grip.
Thinning Pads – Closely inspecting the brake pads themselves will reveal if the pad material is getting low. Most new pads start at 10-12mm thickness. Anything under 3mm remaining is an immediate indication that replacement is needed.
Symptoms of Bad Brake Pads
Worn out brake pads will produce distinct symptoms that alert drivers that immediate maintenance is required. Three key signs that your brake pads are worn out include:
Brake Squeal/Squeaking
As brake pads wear down, the metal backing plate starts contacting the rotor, causing a high-pitched squealing or squeaking sound when braking (1). This sound indicates the brake pads have become dangerously thin.
Vibration in Pedal/Steering Wheel
Bad brake pads can cause the steering wheel or brake pedal to shake when brakes are applied. This vibration is caused by uneven wearing of the brake pads, resulting in rotor runout (2).
Longer Stopping Distance
Worn out brake pads lead to reduced braking power and longer stopping distances. If you find yourself needing to push the brake pedal closer to the floor and brake earlier to stop the vehicle, your brake pads likely need replacement.
Appearance of Worn Brake Pads
There are several visual signs that indicate your brake pads are worn and need to be replaced. These include:
Cracked or broken pads – Pads that are excessively worn will begin to crack or break apart. Small cracks are normal as the pads wear down, but large cracks or pieces breaking off completely indicate the pads are too worn and should be replaced.
Uneven pad thickness – Brake pads wear evenly on both sides of the rotor under normal conditions. If you notice the inner or outer pad is significantly thinner than the other, this indicates uneven wear and the pads likely need to be replaced. Uneven wear can be caused by issues like a stuck caliper piston or worn suspension parts.[1]
Glazing of pad surface – Over time, the surface of the brake pads will become smooth and shiney. This is referred to as glazing and indicates the pads are worn out. Glazing decreases braking power as it reduces friction between the pads and rotors.[2]
By visually inspecting the brake pads, you can check for signs they are excessively worn and need to be replaced for optimal braking performance. Letting pads wear too thin risks brake failure and reduced stopping ability.
[1] https://www.performancehondastore.com/blog/signs-you-need-new-brake-pads
[2] https://www.wagnerbrake.com/technical/parts-matter/automotive-repair-and-maintenance/how-to-check-brake-pads.html
Sounds from Bad Brake Pads
Worn out brake pads can produce some distinct and noticeable sounds. Being aware of these noises can help identify issues before they become dangerous. Here are some of the most common sounds that can indicate worn brake pads:
High-Pitched Squealing
As brake pads wear down, the metal wear indicator starts to rub against the rotor, producing a loud squealing or screeching noise when braking. This high-pitched sound usually means the brake pads are nearing the end of their service life and will need replacement soon.
Grinding When Braking
If the brake pad material wears away completely, you may hear a grinding noise when applying the brakes. This means the metal backing of the brake pad is grinding against the rotor. Continuing to drive with completely worn pads can damage the rotors. Have your brake pads replaced immediately if you hear this grinding sound.
Scraping Noise
New brake pads often produce a scraping or scratching noise as they wear in and mate to the rotor surface. This usually goes away after a few hundred miles once the pads form properly to the rotors. Persistent scraping noises could indicate issues with pad installation or rotors in need of resurfacing.
Dangers of Worn Brake Pads
Driving with worn brake pads can be extremely dangerous and lead to hazardous situations. Some of the main dangers include:
Longer stopping distance – As brake pads wear down, they become less effective at slowing and stopping your vehicle. You’ll need to push the brake pedal farther to get the same stopping power, resulting in longer braking distances. This makes it harder to stop in time to avoid obstacles or collisions.
Brake failure – If brake pads are worn too thin, they can overheat and fade. This means you’ll lose braking power completely for a period of time. Brake failure almost always leads to an accident if it happens when braking is required.
Damage to rotors – The longer you wait to replace worn brake pads, the more damage is caused to the brake rotors. Deep grooves can get worn into rotors by worn pads. This damage is expensive to repair and leads to pulsations and vibrations when braking.
When to Replace Brake Pads
Brake pads generally need to be replaced every 30,000-50,000 miles, but there are some signs that indicate when it’s time for new brake pads sooner:
Appearance: Brake pads should have some material thickness, typically at least 3-4mm. If the pad material is worn very thin or even gone in spots, it’s time to replace them (https://www.kbb.com/car-advice/brake-pad-replacement/).
Symptoms: Squealing, grinding noise, vibration, or pulling when braking all indicate worn brake pads. Replacing pads at the first sign of wear will prevent further damage to the rotors (https://www.bridgestonetire.com/learn/maintenance/when-to-replace-brake-pads/).
Brake inspection: During scheduled maintenance like oil changes, a mechanic can inspect the brake pads and measure the thickness. They will advise if replacement is needed based on their expert assessment.
With rotor replacement: The pads and rotors wear together, so it’s recommended to replace them at the same time. This ensures an optimal braking surface and pad fit.
How to Check Brake Pads
There are a few methods you can use to check your brake pads:
Visually Inspect the Pads and Rotors: Remove the wheels and visually inspect the brake pads and rotors. The pads should have adequate thickness remaining. There should be no cracks, damage or excessive wear on the pads or rotors. The rotors should not show heavy grooving or uneven wear.
Measure Pad Thickness: Using a ruler or caliper, measure the thickness of the brake pad material that remains. This should be at least 3mm or more for safe operation. Anything less indicates the pads are worn and need replacement. Refer to your vehicle specifications for the minimum pad thickness.
Check Wear Indicators: Many brake pads have built-in wear indicators that will make a squealing or scraping noise when the pad material wears down to a certain point. This alerts you that the pads need to be replaced soon. You can also look for wear indicator grooves or notches in the pad surface – if these are flush with the rotor, the pads are worn out.[1]
Cost to Replace Brake Pads
The cost of replacing brake pads varies depending on the make and model of vehicle, as well as the labor rates charged by different repair shops. However, the typical range is between $150-$250 per axle (AACAA). This cost includes the replacement brake pads themselves, as well as labor for the brake job.
Labor costs make up a significant portion of the total brake pad replacement cost. Labor rates can range from $75-$150 per hour, with most brake pad replacements taking 1-2 hours per axle (KBB). The labor time needed will depend on the vehicle’s make and model, with more complicated brake designs requiring additional time.
Besides the replacement brake pads and labor, some additional parts or services may be required during a brake pad replacement:
- Brake rotors may need to be resurfaced or replaced if they are worn down too far (CVT)
- Brake fluid flush to replace old brake fluid
- Brake caliper service if the calipers are sticking
- Wheel alignment to realign the wheels after brake service
These additional services can add $100-$300 or more to the total brake pad replacement cost, but are often necessary to ensure proper brake function. It’s a good idea to have a professional inspection done to identify any other brake parts that need attention.
Preventing Excess Brake Pad Wear
There are a few key driving habits that can help prevent excess brake pad wear:
Avoid overheating the brakes. Brakes can overheat from continuous hard braking, which causes the brake pads and rotors to wear out faster. Give your brakes time to cool down if you’ve been braking hard by avoiding using them for a bit (Sources: https://www.mydriversedge.com/6-mistakes-that-wear-out-brake-pads-prematurely/, https://www.delphiautoparts.com/en-gb/resource-center/article/be-aware-of-brake-pad-wear)
Avoid riding the brakes. Resting your foot on the brake pedal applies constant pressure and heat, even if you’re not slowing down. This can cause premature wear. (Sources: https://www.cbac.com/media-center/blog/2016/august/tips-to-help-your-brake-pads-last-longer/)
Inspect brake pads regularly. Checking brake pads during oil changes or tire rotations allows you to monitor thickness and replace them before they are completely worn down. (Sources: https://www.delphiautoparts.com/en-gb/resource-center/article/be-aware-of-brake-pad-wear)