Brake Systems & Maintenance
This guide is intended to provide you with a basic understanding of how to replace disc brake pads on a common, modern vehicle; not to provide in-depth knowledge of brake systems. It will assume that you are familiar with the basic components of a disc brake system such as the brake pads, rotors, calipers, et cetera. It will be necessary to lift the front of the vehicle and remove the wheels in order to gain access to the disc brakes. Use extreme caution to ensure your car or truck is properly supported at all times. If you have any questions, please do not hesitate to contact us.
Disc Brake Problems
Replacing worn brake disc brake pads is probably the most common service performed on a vehicle's brake system. Fortunately, replacing disc brake pads is very simple and not beyond the scope of the home do-it-yourselfer. In fact, removing and reinstalling the wheels is often the most labor intensive aspect of changing disc brake pads. Furthermore, disc brakes often give plenty of warning when they need to be replaced. Many cars have a device known as a squealer that will touch the surface of the rotor and create a high pitched squeal (hence the nickname) when the brake pads have worn down sufficiently. Other noises coming from the front of the vehicle while in motion may also indicate a problem with the brake pads. Brake noises often change or disappear when the brakes are applied. Regardless, it is important to have your brakes inspected regularly to maintain the safe operating condition of your vehicle.
Removing The Brake Calipers
Once you have determined that you need to replace the brake pads, you can start by removing the brake calipers. Each caliper is held onto the hub or spindle by two slider pins. These pins can be loosened from behind each caliper. The slider pins do not need to be completely removed in order for the caliper to be removed. Some slider pins will require the use of either a large torx or hex socket. Since you have not (and should not have) removed the front brake hoses, the caliper will have to remain tethered to the vehicle. Do not let the caliper hang from the brake hose as this can easily damage the hose or its fittings. Fabricate a simple hook from an old coat hanger and hang the caliper from the top of the strut. Be sure that nobody touches the brake pedal or brake fluid reservoir while the brake calipers are off or the piston may be forced too far out and may rupture a seal. Next, you need to press the piston back into the caliper to make room for the new (thicker) brake pads. With the old brake pads still in place, use a large c-clamp or channel lock pliers to carefully press the piston in. If the piston will not retract smoothly, it may need to be rotated in with a special tool. Now remove the brake pads from the caliper.
Choosing Brake Pads
Your local auto parts store is likely to offer a variety of choices of brake pads available for your vehicle. Normally, it is best to choose the same type of brake pads as were originally used on your vehicle. However, consider that premium semi-metallic brake pads may provide a shorter stopping distance and longer brake pad life than standard organic pads. They are however, harder on your disc brake rotors and they tend to be noisier. For those vehicles that originally came equipped with organic compound brake pads, I often suggest upgrading to premium where the disc brake rotors are fairly inexpensive.
Resurfacing vs. Replacing Rotors
Having worked in the service industry for years, I have often been asked whether resurfacing or replacing brake rotors is really necessary. My answer is always that your brake pads and the surface of your brake rotors are life-mates; change one and you need to change the other. Fortunately, having your brake rotors resurfaced can be done relatively cheap. Some retailers may offer a reduced price on resurfacing the brake rotors if you purchase the brake pads from them. If the rotors are too thin to be machined or if their price is comparable to the price of new ones (which does happen) they should be replaced. Removing the rotors should be easy (in most cases they will just slide right off). Otherwise, check to see if there are any push-nut retainers on the wheel studs holding them in place. If not, tap lightly with a hammer on the center hub of the rotor to free up any corrosion. Some newer vehicles (mainly imports) have two small metric threaded holes in the brake rotor in which the correct sized bolts can be threaded in and used to press the rotor off the hub. Other rotors may need a special tool known as a slide hammer. The last common design is used mainly on older ford vehicles in which the rotor houses the wheel bearings. These will need to be removed before the rotor can come free. Be sure to clean the bearings and repack them with fresh wheel bearing grease before reinstalling.
Installing New Brake Pads
Compare the new brake pads to the old ones. They should be similar in size, shape, and have the same style of shim (if so equipped) attached to the back. In some cases, shims may need to be purchased separately and clipped in place. Snap the brake pads into place in the brake calipers. They should fit nicely into the caliper and clip into place. Permatex Lubricants offers a product called "Disc Brake Quiet" which can be spread on the back of the brake pads before they are installed in the caliper. This product can help reduce any chatter from the brakes and should be available at all major auto parts retailers.
Reinstalling The Brake Calipers
Inspect the old brake pads again for uniform thickness and appearance. If they have worn unevenly there is a good chance that the slider pins are seizing up in the caliper and preventing it from sliding back and forth properly. If necessary, replace or clean and lubricate the slider pins with disc brake caliper lubricant. Although not always necessary it may help extend the life of your new brake pads and rotors. Reposition the the brake caliper on the hub and tighten the slider pins.
After changing the brake pads, be sure to test out the brake pedal before driving the vehicle. Pump the pedal a few times to force the brake pads to squeeze the brake rotors. If the pedal is soft or fades you should consider bleeding the brake system before using the vehicle. Please view our How To Bleed A Brake System guide for more information.