What is Brake Pad?
Brake pads are a component of disc brakes used in automotive and other applications. Brake pads are composed of steel backing plates with friction material bound to the surface that faces the disc brake rotors.
Brake pads convert the kinetic energy of a vehicle to thermal energy through friction. Two brake pads are contained in the brake with their friction surfaces facing the rotor. When the brakes are hydraulically applied, the caliper clamps or squeezes the two pads together onto the spinning rotor to slow and stop the vehicle.
When a brake pad heats up due to contact with the rotor, it transfers small amounts of its friction material onto the disc, leaving a dull grey coating on it. The brake pad and disc (both now having the friction material), then “stick” to each other, providing the friction that stops the vehicle.
In disc brakes, there are usually two brake pads per disc rotor. These are held in place and actuated by a caliper affixed to the wheel hub or suspension upright. Racing calipers, however, can utilize up to six pads, with varying frictional properties in a staggered pattern for optimum performance.
Types of Brake Pads
There are four types of brake pads:
- Non-asbestos organic (NAO),
- Low-metallic NAO,
1. Non-Asbestos Organic or Organic brake pads
Organic brake pads are made of a mixture of common materials like rubber, carbon, glass/fiberglass, and others, secured together by resin. These brake pads are suitable for everyday driving of non-performance vehicles and don’t produce much heat with stopping. These pads are often known as Non-Asbestos Organic (NAO).
These types of brake pads in disc brakes were initially made from asbestos, a heat-absorbing material well-suited for the wear and tear that brake pads take on. However, asbestos was discovered to be a highly-potent carcinogen, causing cancer in those with prolonged exposure.
When these asbestos-based brake pads had worn down, they would release asbestos into the air for drivers to unknowingly inhale. Manufacturers realized asbestos wasn’t a safe compound to use in braking systems. As a result, organic brake pads — or non-asbestos organic (NAO) brake pads — were created to fill the gap.
Organic brake pads, which come standard on about 67% of new vehicles sold within the United States, are made of a mixture of fibers and materials such as rubber, carbon compounds, glass or fiberglass, Kevlar, and are bound together with resin. They tend to produce less dust than some other types of brake pads, such as metallic pads and are available at a lower price point.
The benefits are many:
- Organic Pads are quiet. They do not contain any metal to scrape against the brake rotors.
- Organic Pads provide a comfortable braking experience. The pads are made from highly compacted carbon, Kevlar fibers, fiberglass, and other material. These materials are bound with resin making their operation smoother.
- Organic pads do not create the brake dust which coats the wheels as other brake pads do.
- They are easy on the brake rotors. With no metal parts, they don’t grind down the brake rotor surface.
But there are drawbacks:
- It’s common for drivers to replace the original brake pads sooner than expected. Because of the softer materials, the pads have a shorter life and must be replaced more often.
- They also tend to function best within a smaller range of temperatures. They don’t perform as well as semi-metallic brake pads in extreme weather or when they are being pushed too hard and overheat.
- Organic brake pads also have a higher compressibility level, which means the driver has to press on the brake pedal with more force to engage them.
2. Low-Metallic Nao
These types of brake pads are known to be noisy and to let off a lot of brake dust. Better braking is realized with the Low-Metallic NAO option, the result of an organic formula mixed with between 10% and 30% copper or steel. This recipe certainly helps with the transfer of heat.
3. Ceramic Brake Pads
Ceramic brake pads are made from a durable ceramic compound, often reinforced with other materials to aid in friction and heat management. Ceramic brake pad material, on the other hand, is denser and much more durable. Ceramic brake pads also have fine copper fibers embedded in them to increase their friction and heat conductivity.
While ceramic brakes are typically priced higher, they are very quiet, generate less dust as they wear, and provide consistent performance over a wider range of temperatures and driving conditions.
Since their development in the mid-1980s, ceramic brake pads have enjoyed increasing popularity for a number of reasons:
- Noise-Level: Ceramic brake pads are very quiet, creating little-to-no extra sound when the brakes are applied.
- Wear & Tear Residue: Compared to organic brake pads, ceramic brake pads tend to produce less dust and other particles as they wear down.
- Temperature & Driving Conditions: Compared to organic brake pads, ceramic brake pads can be more reliable in a broader range of temperatures and driving conditions.
However, ceramic brake pads have some limitations. First and foremost is their cost: Due to the higher manufacturing costs, ceramic brake pads tend to be the most expensive of all brake pad types.
Because both ceramic and copper cannot absorb as much heat as other materials, more of the heat generated during braking is conducted through the brake pads and into the rest of the braking system. This can lead to increased wear on other brake components.
Finally, ceramic brake pads are not considered the best choice for extreme driving conditions. If you are choosing between ceramic and semi-metallic pads in very cold weather or with a race coming up, go for metallic.
4. Semi-Metallic Brake Pads
The final type of brake pad is the semi-metallic brake pad. Semi-metallic pads differ from full-metal pads in that they use fillers to make the pad compound, rather than using 100% metal. Full metal brake pads are usually reserved for really extreme braking requirements
Semi-metallic (or often just referred to as “metallic”) brake pads contain between 30-70% metals such as copper, iron, steel or other composites and often a graphite lubricant and other durable filler materials to complete the manufacture. Semi-metallic brake pads can serve a variety of functions, from everyday driving to track performance.
For many drivers, especially those who value high performance, the choice between ceramic and semi-metal brake pads is an easy one. Performance-oriented riders tend to prefer the metallic brake pads as they offer improved braking performance over a much wider range of temperatures and conditions.
Because metal is such a good conductor of heat, metallic brake pads tend to withstand more heat while also helping brake systems cool down more quickly. They also don’t compress as much as organic brakes, meaning less pressure has to be applied to the brake pedal to affect braking ability.
However, there are some disadvantages when it comes to metallic versus ceramic and organic brake pads. Metallic brake pads tend to be noisier than their ceramic or organic counterparts, resulting in a noisier ride.
Metal pads also put more stress on the braking system, increasing the stress and wear on the brake discs. Metallic brake pads are priced between organic and ceramic pads. They also tend to produce more brake dust than the other two varieties.
What are the differences between semi-metallic and ceramic brake pads?
The difference between ceramic and semi-metallic brake pads is simple – it all comes down to the materials used to manufacture each brake pad.
When choosing a ceramic or semi-metallic brake pad for a vehicle, there are certain applications where both ceramic and semi-metallic pads offer different advantages.
For performance vehicles, track driving, or towing, most drivers prefer semi-metallic brakes because they provide better stopping power over a wider range of temperatures and conditions. They are made of a material that conducts heat well, making them better able to withstand higher temperatures during braking while also helping to cool the system.
Semi-metallic pads can be noisier than ceramic pads and are typically priced between organic and ceramic pads.
Ceramic brake pads, while quieter, can also handle extremely high temperatures with quick recovery, resulting in less damage to the rotors. Ceramic pads produce finer dust as they wear than semi-metallic pads, leaving less dirt on the vehicle’s wheels.
Ceramic pads typically last longer than semi-metallic pads and offer better noise control and less rotor wear throughout their life without sacrificing braking performance. When deciding between ceramic and semi-metallic brake pads, remember that not all vehicle makes and models are compatible with ceramic brake pads, so research is advisable.
When To Replace Your Brake Pads or What Happens When Brake Pads/Shoes Wear Out?
Every time you engage your vehicle’s brakes, a small amount of friction material is worn off the pads and/or shoes. Over time, the friction material will become thinner. If the pads or shoes are not replaced, the friction material will be worn off entirely, exposing the steel pieces that held the material.
When these steel pieces come into contact with the discs or drums, excessively long braking distances and damage to the discs and drums will result. Look for these signs to know when to replace brake pads or shoes:
1. Squealing or Screeching Noises
If a vehicle’s brake pads have wear indicators, a driver may notice a squealing, screeching or whining noise when the brakes are engaged. This sound is caused by a small metal attachment on the brake pad backing plate for just this purpose.
Wear indicators work on the same principle as dragging fingernails across a chalkboard. When you hear it regularly while braking, it’s time to bring your car to a brake specialist for an inspection. Note that not all brake pads come with this feature, so don’t rely on sound alone to assess your brakes’ condition.
When brakes are exposed to wet, damp conditions, such as after a rainstorm, pads may exhibit a very similar screeching sound while braking. If a sound disappears after the first few times you use your brakes, that’s a good indicator that it was just a bit of moisture on the brake pads or shoes and not a sign they need to be replaced.
2. Less Than a Quarter Inch of Brake Pad
On disc brakes, you can also visually inspect your brake pads to know if it’s time to have them replaced, though it may require you to remove the wheels to do this. Looking down on the brake assembly or “caliper” holding the brake pads, you should see your brake pads compressed against your brake rotor.
If the friction material on the pad or shoe is less than ¼ inch thick (about seven millimeters), consider having your brakes inspected, especially if it’s been a long time since your last inspection.
3. Deep Metallic Grinding and Growling
If you hear a deep, low noise that sounds like metal grinding or a rumbling growl, that can be a sign that not only are your brake pads worn away but also your brake pads or shoes’ backing plates are making contact with the discs or drums.
Since this metal-on-metal contact can very quickly cause even further damage to your braking system, bring your vehicle into a service shop as soon as possible if you hear this type of noise.
4. Indicator Lights
Some vehicles have an indicator light on the dashboard that will signal when it’s time to replace the brake pads. Check your owner’s manual to see if your vehicle comes equipped with a low-pad warning system. Remember that if the light does come on, you’ll need to have your mechanic replace the warning sensors as well as the brake pads.
How Long Do Brake Pads and Shoes Last?
The real answer to how long brake pads and shoes can last will vary from vehicle to vehicle and from driver to driver. For example, if you tend to drive the most often in urban areas or in heavy commuter traffic, you’ll be engaging your brakes a lot more frequently than someone who drives in rural locations or on highways.
Some people also tend to “ride the brake,” meaning they press and depress their brakes more habitually than other drivers, causing the brake pads to wear away more quickly. Brake pads and shoes are generally thought to be good between 30,000-35,000 miles in urban use. In less demanding situations like highway driving in light traffic, brakes may last 80,000 miles or more.
What are the 4 types of brake pads?
There are four types of brake pads—semi-metallic, non-asbestos organic (NAO), low-metallic NAO, and ceramic—and it’s important to know which type is best for your vehicle.
What are the different types of brake pads?
These days, drivers typically have a choice between three types of brake pads: ceramic vs. semi metallic vs. organic brake pads.
Are ceramic or metallic brake pads better?
Ceramic brake pads typically last longer than semi-metallic brake pads, and throughout their lifespan, provide better noise control and less wear-and-tear to rotors, without sacrificing braking performance.
Are all brake pads the same?
No, almost every vehicle model has a different shape of the brake pad. The friction materials that are on the pad are different because almost every vehicle has different requirements and performance capabilities.
What kind of brake pads lasts the longest?
Made from ceramic materials mixed with copper fibers, ceramic pads were designed for driver comfort. They are the least noisy, produce very little messy brake dust, and are stable over a wide range of temperatures. And they last the longest.
What are sintered pads?
Sintered, or metallic, brake pads are made of a mixture of metallic particles pressed together. They are more durable than organic pads and should last longer because they can handle dirt and damp conditions a lot better.
How long should brake pads last?
Brake pads generally last between 30,000 and 70,000 miles, but some can last as long as 100,000 miles. There are many factors that account for this wide range. First, brake pads come in a variety of types and compositions and are attached to even more varying brake systems and rotors.
What’s the difference between semi-metallic and ceramic brake pads?
Additionally, ceramic pads have less cold bite than semi-metallic brake pads, making them less effective in very cold weather. They also tend to have a lower coefficient of friction than semi-metallic brake pads (a higher coefficient of friction means better braking ability).
How do you know if your brake pads are ceramic?
Don’t judge a brake pad on just the color of the friction material. Not all dark grey friction materials are semi-metallic brake friction materials, some brake pads with this color could be ceramic or NAO materials. To find out the friction type, use the box or the brake pad manufacturer’s catalog.
Why are ceramic brakes so expensive?
The reason they are so expensive is all down to the production process. It takes a long time and a lot of effort to build them, with each brake disc taking the best part of a month to make.
Are Copper-free brake pads better?
Many of this new reduced-copper and copper-free friction materials actually perform better than the last-generation friction materials they replace. Improvements include better-stopping power, improved wear resistance, and reduced dusting and noise.
Do You Need to Replace All 4 Brake Pads?
There are brake pads on each of your vehicle’s wheels. Most mechanics recommend replacing brake pads in the front or brake pads in the rear at the same time. If one brake pad on the front axle is replaced, then all brake pads on the front axle should be replaced.
How do you choose brake pads?
You need to consider how long the pads are designed to last as well as the rotor when engaging the brake pads. Noise and Vibration: You’ll want to consider how much noise, vibration, and even pedal feel pressing down on the brake pad will cause. Dust Levels: Brake pads may collect dust that then clings to your wheel.