Finding the Best Brake Pads: Factors to Consider

How to Choose the Best Brake Pads For Your Vehicle

Selecting the appropriate brake pads for your particular vehicle can make a significant difference in stopping power, noise levels, and overall driving experience. Here’s a comprehensive guide to help you choose the best brake pads for your vehicle.

There are four types of brake pad friction materials, and they each have pros and cons. I’ll help you figure out which are the best brake pads for your car or truck

Understand the Types of Brake Pads

• Ceramic Brake Pads— More than 70% of all new vehicles come equipped with ceramic brake pads. They’re known for their longevity, low noise, and minimal dust production. They provide excellent stopping power and are gentle on the brake rotors. However, they are generally more expensive and may not be the best choice for high-performance or truck applications.

• Semi-Metallic Brake Pads— These pads are a mix of metal fibers and other materials. They offer good performance, durability, and heat dissipation, making them suitable for a wide range of driving conditions, including light trucks and performance vehicles. However, they can be noisier and produce more dust than ceramic pads.

• Organic Brake Pads— Made from materials like rubber, glass, and resins, organic pads are softer and quieter than metallic pads. They are also less expensive but tend to wear out faster and produce more dust. They are suitable for light-duty use and everyday driving.

• Low-Metallic NAO (Non-Asbestos Organic) Pads— These pads contain small amounts of metal, such as copper or steel, to improve braking performance. They offer a balance between the quiet operation of organic pads and the durability of semi-metallic pads. However, they may produce more dust and noise than ceramic pads.

Each type of friction material is made from 10-20 different raw materials and in different percentages to match the requirements of each year, make, and model vehicle. Even though brake manufacturers label their friction material according to the type, no friction material is completely non-asbestos organic, semi-metallic or ceramic.

The pros and cons of each brake pad type

Non-asbestos Organic (NAO) friction material pros and cons

NAO friction material stops your vehicle using adherent friction. They’re the least expensive of all types. NAO friction material usually contains some metallic strands (typically less than 20%) as well as organic fibers like fiberglass and aramid to maintain structural stability. The pad also contains fillers like potassium, fiber wool, silica, zirconia, alumina and silicon carbide, friction powder or friction dust, lubricant (usually graphite) and a binding agent (glue).

NAO pads are quiet and provide smooth braking with little vibration. They’re the softest and most compressible of the three types, so they wear faster than the rotor. They require added braking pressure as they heat up due to their compressibility and their tendency to “outgas” and fade at high temperatures. Depending on the formulation, they have excellent braking performance below 400°F but provide poorer braking and wear faster at higher temperatures found during hard braking. Some NAO pads tend to squeal during the first application on cold mornings. Fewer car makers are installing NAO pads at the factory. Most have switched to ceramic friction materials.

Pros: It is the least expensive of the three types. It is quiet, except during initial braking in the morning, and it is easy on the rotors.

Cons: They wear quickly and create lots of brake dust. They require more brake pedal effort as they heat up. Most fade of all three types with longest recovery (cooling) time between brake applications.

Semi-Metallic friction material pros and cons

Semi-metallic friction materials stop your vehicle using abrasive friction. They contain 30%-65% chopped steel, iron, and brass metal fibers and flakes to create friction and dissipate heat. They also include fillers, which can include everything from rubber dust, cashew dust, mica, and vermiculite to calcium carbonate and potassium titanate, as well as lubricants and binding agents. Semi-metallic pads provide aggressive braking even at high heat and have excellent fade resistance. They provide poorer braking at temperatures below 212°F but offer the best braking and excellent wear at temps above 400°F. Semi-metallic pads provide excellent stopping properties for heavy vehicles and loads, but they make more noise and create more vibration, harshness, and dust than the other types. They also wear rotors faster than either of the other two types.

Pros: Most aggressive of all three types. Excellent high heat braking with less fade.

Cons: They are more costly than NAO. They create the most noise, vibration, and harshness. Poor cold braking. Brake dust contains metallic particles that rust and discolor wheels. Most rotor wear.

Ceramic friction material pros and cons

Ceramic friction materials stop your vehicle using adherent friction. They’re made with porcelain bonded to metal flakes or filaments to provide excellent structural stability and heat dissipation when exposed to tremendous heat. Ceramic fillers such as ceramic powder and potassium titanate, as well as abrasives like zirconia or alumina, lubricants, and binding agents, are also used.

Pros: They provide better braking and last longer than NAO material. Ceramic friction materials produce less noise and dust than NAO or semi-metallic.

Cons: Highest cost. Easy on rotors. However, since ceramic materials don’t dissipate heat as effectively as semi-metallic brake pads, they can overheat brake rotors on heavy brake applications or during extended use. Ceramic pads are most likely to cause brake pedal pulsation due to disc thickness variation brought on by lateral run-out. Extreme care is required when installing ceramic brake pads to ensure the wheel hub is within specification and clean and lug nuts are torqued evenly with a torque wrench to avoid lateral run-out.

Understanding the two types of friction and how they stop your vehicle in different ways

Brake pads stop your vehicle by converting kinetic energy (motion) into heat using either an abrasive or an adherent type of friction material. Although, even here, no brake pad formula is completely abrasive or completely adherent. Here’s how the two friction methods work.

How abrasive friction works

Most semi-metallic brake pads use abrasive friction. Abrasive friction transforms motion into thermal energy by breaking the chemical bonds of the brake pad‘s friction material and the metal in the rotor. Abrasive brake pad friction material contains abrasive crystals, metallic fibers and metal powders, lubricants, and a binding agent to form a brake pad that’s harder than the rotor. As the name implies, abrasive friction works by “abrading” the rotor. It’s really that simple.

Need a real-world analogy? Chuck a round piece of hardwood into a lathe and hold a sanding block against it while it’s spinning. The wood represents the rotor, and the sandpaper is the brake pad friction material. The abrasive particles in the sandpaper dig into the spinning wood, creating heat. If you press hard enough, the abrasive particles can dig in enough to stop the lathe from turning. The same applies to abrasive brake pad friction material; it digs into the softer rotor to stop the vehicle. Since the brake pad is harder than the rotor, it wears out the rotor faster than the pad.

Abrasive friction Pros:

Abrasive brake pads provide maximum stopping power. They handle high heat loads and are more resistant to brake fade. They’re used in some light trucks and full-size SUVs. They’re also used in racing to provide maximum braking at high speeds.

Abrasive friction Cons:

They wear out the brake rotor faster. They make more noise. They give off metallic brake dust that rusts and deposits on your alloy wheels. They vibrate more and that generates brake harshness. Abrasive brake pads cost more than adherent NAO style pads (described below).

Adherent friction works with by rubbing the brake pad against a transfer layer

NAO and Ceramic brake pads stop your vehicle using adherent friction that transforms motion into thermal energy but does so by rubbing a sticky film of brake pad’ material onto the rotor during the break-in/bedding process. That film is referred to as a “transfer layer.”

The bedding process deposits a transfer layer onto the rotor face and smooths any roughness or irregularities on the pad and rotor contact areas while physically and thermally converting the pad and rotor surfaces. From that point on, every time you brake, you’re rubbing two sticky surfaces together: the sticky surface of the brake pad’s friction material against the sticky transfer layer.

Need a real-world example? Get a kid’s lollipop. Wet it and wipe the sugary liquid onto one hand. Let your hand and the lollipop dry. Your hand is now the rotor, and the dried, sugary coating is the transfer layer. Now rub the sucker back and forth against your hand until it warms up. As things heat up, you create heat and friction, and it will be harder to rub the two together. That’s adherent friction.

During braking, the transfer layer disintegrates, and a new layer is deposited onto the rotor

The high heat of braking disintegrates the transfer layer and the hot friction material continually wipe son a new layer. The dust you see from adherent brake pads is mostly burned up friction material. In an adherent system, the brake pad wears faster than the rotor.

Adherent friction Pros

Adherent brake pads provide less rotor wear and make less noise. Adherent braking systems are used on most small- to medium-sized passenger cars, crossovers, light trucks, and small SUVs.

Adherent friction Cons

Adherent brake pads wear faster and make more brake dust (but that dust is less likely to discolor your allow wheels). Most adherent brake pads can’t handle the braking requirements of heavy vehicles or vehicles that carry large payloads because the high heat causes brake fade. Also, adherent friction efficiency depends on a uniform thickness of the transfer layer over the entire face of the rotor. To achieve that uniform transfer layer, you need near-perfect parallelism between the rotor and the wheel hub. If the rotor has more than .002” lateral run out, the rotor will develop disc thickness variation where the transfer layer is thicker on opposite sides of the rotor. Disc thickness variation causes brake pedal pulsation and “judder” that’s often misinterpreted as “rotor warp.” Even something as simple as uneven lug nut torque can cause lateral run out and disc thickness variation.

©, 2019 Rick Muscoplat