While many novice vehicle owners assume that disc brake systems are fully integrated, and only represent themselves as a single component, this is an erroneous assumption. As a matter of fact there are typically five sub-units involved with a singular disc system package; the disc rotor; a caliper assembly; brake pads of varying size and material types fitted within the caliper housing; and finally a wheel hub, in addition to a congruent cluster of wheel studs, that provide a way for the customer to attach a wheel and tire combination to the car’s overall axle/ suspension system.
In this particular disc brake system primer we will focus on the brake pads themselves, since in effect this sub-component is where the ‘caliper hits the rotor’ as it were.
What are brake pads anyway?
As a contiguous component within a typical disc brake system, brake pads serve as the primary friction contact point between the brake system’s hydraulic caliper, and the brake rotor as it spins on the wheel hub. As a dynamic process, pads create direct friction that, in turn, marginalizes, and ultimately eliminates the rotor’s system’s kinetic energy, while translating that force into thermal energy as a final result.
Today’s systems typically employ two pads per caliper in the case of consumer cars, although in some specialized cases additional brake pads are involved. These alternative approaches include certain kinds of heavy duty brake systems for industrial use, in addition to highly specialized aviation applications.
Typical brake pad materials
Depending on their purpose, there are four common types of materials involved in the use of today’s brake pads. These types include:
Non-metallic – These products are designed to combine various composite sub-materials including cellulose (a green plant derivative) Aramid (synthetic fibers exhibiting significant linear strength when grouped together), and varying degrees of fritted glass (glass particles that allow gas derivatives to pass without abatement).
Semi-metallic – These products are typically compromised of hybridized copper, iron and/or steel equaling from 30% to 65% of an entire pad’s surface. The rest of the pad structure involves a range of sub-materials necessary to establish reliability.
Fully-metallic – These products are typically considered to be race-only variants, and only useful in the case of high-dependability, high-heat applications. These products are constructed using metal-only processes, leveraging a fritted design similar to gas-out processes that relate to non-metallic pads.
Ceramic – These products are considered to be the most sophisticated of today’s brake pad variants. They are comprised of porcelain and clay derivatives in combination. While they are typically considered to be the quietest of all pad types, they are particularly expensive. Consequently, they are rarely found on consumer vehicles, and only show up on the most expensive vehicle brands.
What types of brake pad brands are available?
Signs relating to a requirement for brake pad maintenance
Now that you know a little about what, and how pads apply to your consumer or performance road car, let’s take a look at various characteristics that presage the need for brake pad servicing. These include:
Squealing during braking – This occurs when pad depth becomes so thin that contact between the caliper housing and the rotor itself can occur.
Uneven braking – This warning sign occurs as a consequence of uneven pad wear. This occurs when one brake is reaching optimum contact pad pressure on the rotor, while another doesn’t.
Pedal play – Another way to announce that your brake pads need tending relates to pedal length. The longer the pedal, the thinner the pad depth. While there are other consequences implied here maintenance should be conducted without fail.
Grinding sounds during braking – This represents one of the most common of all tale-tells, and occurs when the disc caliper comes in direct contact with the rotor. If you hear this sound, you should respond immediately.
Brake pedal vibration – Similar to the issue of pedal play, vibration during the braking evolution suggests a requirement to replace your brake pads. You can read more about how to replace brake pads on our blog. Brake pad wear alarm on the dashboard.
Some premier brands install pad sensors at each brake system. When the pad depth reached minimum depth, the sensor triggers a dash alarm. If this particular dash annunciation appears brake pad maintenance is necessary.
Of course, if you feel your brake pads are beyond repair, we’d strongly recommend that you purchase a new set of brake pads. You can read more about the cost of replacing brake pads, as well as a number of other helpful tips; within our blog section.