Many people who are comfortable doing basic services on their cars, like oil changes and other regular maintenance, might think that replacing the front disc brakes is too difficult, or are afraid they might do something wrong and lose brakes while driving.
Replacing your disc brakes is among the easiest jobs the home mechanic can perform. Using a high-quality service manual when replacing your brakes will help show the step-by-step procedure and describe differences in your vehicles disc brakes.
When disc brakes need to be changed, you will likely hear scrapping, squealing and dragging sounds. your brakes may pulse or shake, and they won’t work as well as they used to. Inspecting disc brakes for wear is easy. You can tell it is time to replace brake rotors when you can see deep gouges on the surface. If possible, you can look at the pads and see how much thickness there is. Always replace both front, both rear, or all your brakes. Doing one at a time will lead to premature wear and improper brake function.
This walk-through will show you some of the basic steps to take and point out some pro tips for making sure your next brake replacement job is easy, fun and saves you a ton of money.
Before getting into the job, make sure you have a few simple tools handy. You will need a jack strong enough to raise your car and jack stands to support your car while working on it. Never work on a car that is supported by a jack. If it fails, and they do, you can be seriously injured or killed, and it’s almost guaranteed you will damage your car.
You will also need to have the correct lug nut wrench for your car and a set of sockets or wrenches. To do the job right, you will need a torque wrench. Have a medium c-clamp handy as well. A short piece of rope, an old metal coat hanger or something similar will be needed, too. Buy a can of Brake Parts Cleaner from an auto parts store, and have disc brake grease handy. Most auto parts stores sell single-use brake grease packets.
Have parts ready. You will need a good quality set of brake pads and brake pad grease. If you plan on replacing rotors, have them available. Otherwise, you will have to take the used rotors to a shop and have them inspected and resurfaced.
When ordering replacement brake parts for your car, buy the best parts you can find. There are lots of places were buying cheap parts is fine, but your brakes are not one of them. Read the section on Brakes in your workshop manual before beginning. This will get you familiarized with the names of parts and how they work together.
Unless you are using air tools, you should loosen the lug nuts before raising your car. Lug nuts can be tricky to remove once the car is in the air. You don’t need to remove them all the way, and you should not, just make sure they are loose enough to be removed later.
Jack up your car and support it on jack stands. Your service manual will tell you where the safest jacking points and places to put stands to make sure your car is well supported. Once you have the car on the stands, remove the lug nuts, wheels and tires.
Disc brakes are comprised of two elements- the rotor and the caliper. The caliper holds the brake pads and uses hydraulic pressure to apply pressure when you push down on the pedal.
Pro Tip: Disassemble and reassemble one side at a time. This way, you will have a reference if you forget how things go back together.
Unless you plan on replacing the caliper, do not remove the fluid lines from the caliper. On the back side, you will see at least one and usually less than three bolts holding the caliper to a bracket that is either part of the steering or is bolted on. Typical set-ups use two bolts. Remove these then carefully lift the caliper assembly off the rotor. You may have to use a screwdriver or a small bar to help remove the caliper. Do not hammer on calipers!
Use the piece of rope, hanger or whatever you have handy to support the caliper so that it is not hanging on the hose. Hanging the caliper on the hose can cause it to weaken, tear and burst. Usually, the caliper can be hung from the front suspension.
With most cars and trucks, the brake rotor will now be free to remove. On some cars and trucks, you will need to remove the wheel bearing nut. A repair manual will tell you if this is necessary. If you are replacing the rotor, you will not need to do anything with the old one. If you hope to reuse the rotor, take it to a machine shop and have it surfaced and measured. This is a cheap step and ensures that the new pads you install will have a good surface to work against.
Your repair manual will show you how your pads are held in place. Common caliper designs use pins that the pads slide on. Others use metal clips to support the pad inside the caliper. Once you have removed any components that hold the pads in place, simply press them away from the caliper until they are loose.
Compare your new pads and rotors to your old ones, making sure they are the same shape and size and have the correct holes and clips.
Clean the mounting surfaces of the caliper where the pads mount with brake parts cleaner. Once clean, avoid touching parts any more than is absolutely necessary. Any grease or oil that comes in contact with the rotor or the friction surfaces of the pads needs to be cleaned off completely.
With the pads removed, you will see the inside of the caliper has either one, two or more round pistons that move in and out to apply pressure to the pad. These will need to be compressed to install the caliper onto the rotor with new pads.
To compress the pistons, use the c-clamp with a dowel, an old socket, or any strong, straight object that will reach the pistons. It should not take much force to compress the pistons. If they do not move, it is likely you have a stuck piston and will need to rebuild the brake caliper.
Once the pistons are fully compressed, apply brake grease to the contact surfaces of the caliper according to the directions in your workshop manual.
If your new pads came with clips, brackets or other replacement components, install them on the new pads the same way the old pads are installed. Avoid using used clips and springs when possible, as they may have worn out and won’t work well, causing difficult to diagnose problems. If you are not sure about how the clips are installed, a service manual will show you where they go.
Load the pads into the calipers the same way they came out, making sure the friction surface is toward the rotor. You may have to wiggle and press a bit to get the pads to line up, but they will eventually slide into the caliper and fit flush against the greased mounting surfaces.
You can now gently remove the hanger from the caliper and slide the loaded caliper onto the rotor so that the mounting bolts line up. Install the bolts hand tight before tightening them down all the way.
If your pads are too close together to fit over the rotor, you will need to compress the pistons again. This is not uncommon, as they will slowly expand without pressure on them.
Your repair manual will tell you what the specified torque for the caliper retaining bolts is supposed to be. Make sure these bolts are good and tight. Loose caliper bolts will cause all kinds of problems from steering issues to ineffective brakes, and can even cause catastrophic loss of control.
Next, reinstall your wheels and tires. You can install the lug nuts as tight as possible with the car still in the air, but unless you are using air tools, the car will need to be on the ground before the lug nuts can be torqued. At this point, you just want to make sure the wheel is flush with the wheel hub before the car is taken off the stands.
Remove the car from the stands and finish torquing the lug nuts to the specification provided in your service manual. You will want to start the car and press the pedal several times to make sure it has pressure. Check the brake fluid level to make sure it is at the correct level. If you disconnected the brake hoses, a brake bleed will be needed in order to get brake pedal pressure.
That is it. Really. It really is that easy to replace disc brakes. The average person can do the job in less than two hours, and you could save hundreds of dollars doing it yourself.
At the end of the end of the day, you will have pride in the work you have done, and your car will stop like new. You can brag to your friends about how easy and fun the job was to do, and you won’t have to deal with high repair shop costs.