How to Guides

Disc Brake Pad

Zaki Moulvi posted this on Jun 16, 2014

Disc brake pads are arguably the most often replaced part on a motor vehicle.  Their constant exposure to high heat and pressure causes them to wear down quickly, necessitating new ones often.

Disc Brake Pad History

Although disc brake systems were first developed in the 1890’s, there use was not commonly seen until the mid 1960’s.  Before then, drum brakes were the choice for most manufacturers in braking systems.  Once it became clear that disc brakes were more efficient then drum brakes and had better stopping capabilities they became more commonly used.

How Disc Brake Pads Work

At the heart of the disc brake system is the disc brake rotor and pads assembly.  The rotor is a flat metal plate that is spinning along with the cars tires.  On top of that plate is a caliper which houses the disc brake pads.  As the brake fluid applies pressure to the caliper, it is forced to clamp down onto the disc brake rotor, pressing the disc brake pads onto the surface.  In doing so, a tremendous amount of friction is created, forcing the disc brake rotor to come to a stop.  When it does, the spinning tire will stop along with it.

Disc Brake Pad Materials

The disc brake pad by itself is quite simple.  A formed pad composed of friction material is mounted onto a steel backing plate.  When first created, asbestos was the compound most often used in the construction of the pad.  When the dangers of asbestos in the ‘90’s, car manufacturers needed to find a new material to work with.

  • Organic disc brake pads are composed of materials such as cork, combined with a 20% metal content.  They offer quiet operation and will help extend the life of your disc brake rotor thanks to the lighter material being used.  They are inefficient as performance pads however and do not perform well when exposed to great amounts of heat.
  • The most common disc brake pads in use are semi-metallic pads.  These are comprised of a hard resin matrix with added steel fibers to give them more strength.  Other types of metal may also be combined to give optimal performance.  The biggest advantage to the semi-metallic disc brake pads is their performance when exposed to heat.  These actually work better under those conditions.  Their flaw is the roughness, which causes cuts in the surface of the disc brake rotor.  They are also noisier than organic disc brake pads.
  • Ceramic pads is the most recent type of material introduced.  Along with metal shavings, these contain particles of ceramic as a main component of the binder.  This type of pad offers superior performance under heat and cold.  The friction provided is stable and consistent, giving the vehicle outstanding braking capabilities.  They are also quieter and produce a minimal amount of brake dust.  Their only downside, and the reason why ceramic disc brake pads are not in common use is their high price.

Choosing the Right Disc Brake Pads for Your Vehicle

For normal use, it is recommended that you follow manufacturer suggestions and keep the disc brake pads that came with your car.  Most likely this is a semi-metallic disc brake pad.  If you prefer a better stopping capability then upgrade to ceramic brake pads.  With these you get an improved brake pedal feel and decreased stopping distances.  Semi metallic brake pads are best used with:

  • Street cars with a high horsepower
  • Tow vehicles or other vehicles that do a lot of heavy hauling
  • Road racing or circle track racing
  • Vehicles that are often in extreme driving conditions, such as in mountainous terrain, or heavy stop and go traveling.

If price is not an issue, then ceramic brake pads are best for cars that:

  • Are driven daily
  • Are built for high performance street driving

You want ceramic brake pads in your car if an improved pedal feel, low dust and a longer rotor life are important to you.

Disc Brake Pad Maintenance

Part of the design of a disc brake pad is a metal wear indicator that will contact with the disc brake rotor if the disc brake pad material becomes dangerously low.  It will produce a loud screech from your brake assembly, alerting you that it is time to change the disc brake pads.  Due to different driving styles and usage, it is impossible to predict how long a disc brake pad will last, making that wear indicator an important component in the maintenance of the brake pads.

Changing Disc Brake Pads

When it is time to change your disc brake pads, it should be done as soon as possible.  The metal wear indicator is digging grooves into the disc brake rotor which will affect that parts performance as well. 

Changing the disc brake pads is fairly easy to do.  Once you have the tire removed you should be able to pull the caliper away from the rotor, slide out the worn pads and replace them with new.  The hardest part of dealing with any disc brake assembly repair is the need to bleed the system afterwards of any air that may have entered.

As car technology has evolved, so have the options for your disc brake pads.  Now a days you can choose the type that is best suited to your vehicle and the way that you drive it.

Categories: Autowiki Car Systems