Brake pads are a normal wear item on your vehicle. That means they are designed to wear down and be replaced. If you have disc brakes on your vehicle, this is a very manageable task and only requires a few tools.
I've included an image from howstuffworks.com to illustrate how disc brakes work. Essentially, hydraulic pressure forces a piston against the brake pads set inside the brake caliper. The caliper is free floating so that the pressure from the pads is evenly applied to each side of the brake rotor to slow or stop the wheel. The rotor is connected to and spins with the wheel and hub. The friction of repeated stopping will wear down the brake pads. The rotor wears as well, but the pads wear much faster.
If you notice any squealing or scraping noises while driving your vehicle and applying your brakes, that is a good sign that your pads are worn and in need of replacement. You might also hear squealing or scraping sounds while NOT applying the brakes and when you apply the brake, the noises stop. That is also an indicator of worn or misaligned pads.
Tire iron or breaker bar that fits lug nuts
wrench (to fit caliper bolt)
Replacement brake pads (for your specific vehicle)
Step 1: Removing the Wheel
Before starting, make sure your vehicle is parked on a flat level surface and you have your parking brake set. This is to make sure your vehicle doesn't roll off the jack which could be quite dangerous. If you do not have a floor jack or a breaker bar that fits your wheel's lug nuts, you can use the scissor jack and tire iron that came with your vehicle...they will work just fine for this. If you do use a breaker bar with a socket, make sure it is the correct size for the lug nuts otherwise you could round off the corners and make removal difficult. I do recommend buying a set of jack stands in either case because they are pretty cheap and provide much more safety for you when your vehicle is elevated off of the ground.
Before jacking up the vehicle, you can use your tire iron or breaker bar to break loose the lug nuts on the wheel. This is much easier and safer while the car is firmly on the ground because it might require a decent amount of force to loosen them. If you have difficulty, try to position yourself to use your own body weight to help loosen the lug nuts.
Using your floor jack or scissor jack, elevate the vehicle using the jack points defined in your vehicle manual. Once the wheel is clear of the ground, place your jack stand in position to support the vehicle. If you are using a hydraulic floor jack, you MUST use a jack stand as the floor jack will tend to "sink" over time. A scissor jack is less likely to move, but I still recommend jack stands...better safe than sorry.
With the wheel safely off the ground, go ahead and remove the lug nuts. After they are removed, you can slide the wheel off of the hub and set it aside. You now have access to the rotor and brake caliper.
Step 2: Remove Old Brake Pads and Open Piston
Remove the bolt and the caliper should rotate up. You may need to use a second wrench on the caliper bolt bushing to keep it from spinning. If it rotates with the bolt, then you are not loosening the bolt yet. Some brake pads have small rivets on the back that might catch on the edge of the piston. If this happens and you can not rotate the caliper, you may need to use a wrench, screw driver, c-clamp, etc. to try to compress the piston enough to clear the rivets. To avoid risk of damaging hydraulic components, open the bleeder screw on the back of the caliper before compressing the piston.
With the caliper open, you can pull the old pads away from the rotor and remove them from the brake assembly. Pay attention to any differences between the inside and outside brake pads to facilitate the installation of the new pads later. As the pads wear, the piston continues to rest in a more "closed" position. In fact, it would not fit over the larger thickness of your new pads. I use a C-clamp to compress the piston back to the fully open position. This process forces some of the brake fluid in the hydraulic system back into the master cylinder. You can use alternative tools to compress the piston, but I found the c-clamp works well for me.
This is also a good time to inspect the rotors for any excessive or uneven wear. Rotors will thin over time and excessive braking can warp them. This will cause a throbbing feel when applying brakes. Rotors can be machined to repair them or simply replaced. If you do find any concerning problems with your rotors, you may want to postpone your brake pad replacement until you can address the rotors.
Step 3: Installing New Brake Pads
Now we are ready to put the new pads in place. There is typically a pair of notches, top and bottom, that small tabs on each end of the pads will seat into. As shown in the photos, seat one tab in the bottom notch, the rotate the pad into place and press into the upper tab into it's notch. Repeat on the inside brake pad. Sometimes the inside and outside pads are different and might have different shapes or metal tabs on them. Just make sure you are installing the pads in the same way you saw them before you started. On this specific vehicle, the inside and outside pads were identical.
You can apply some brake lubricant to the piston, bushings, bolts, etc. to improve the life of the system. Do not apply lubricant on the friction surface of the pads or rotors. The caliper bolt we removed could just some lubricant as well.
Step 4: Close Up the Caliper
With the new pads in place, you are ready to close the caliper. Rotate it back down into position. You might need to press in caliper bolt bushing and/or jostle the caliper in or out to fit over the new thick brake pads. Once you have the caliper lined up, reinsert the bolt and tighten it back in place. You might need to use a second wrench again to hold the bushing in place while tightening the bolt.
Step 5: Reattach the Wheel
Place the wheel back on the hub by lining up the hub bolts with the wheel openings. You may need to re-elevate the vehicle with the jack if you no longer have proper clearance to get the wheel on. Twist on the lug nuts by hand to get the wheel snug against the hub. You can use your tire iron or breaker bar to tighten them down a bit here if you like. Tighten the bolts by switching back and forth to opposing lug nuts (pattern indicated in photo). This helps to make sure the wheel is seated flat against the hub. Otherwise, it could wobble and damage your vehicle while driving.
Once the wheel is bolted on, remove the jack stand and lower the jack all the way down. Now tighten all of the lug nuts again to the proper torque as suggested by the manufacturer. Clean up and put away all the tools.
Step 6: Test Brakes
The job is almost done, but there is one last step. You need to test and make sure the brake system is functioning as expected. Enter your vehicle and crank the engine, but leave the parking brake set and do not put the vehicle in gear yet. Press the brake pedal and it should go all the way to the floor with very little resistance. This is normal and happens because we forced the hydraulic fluid back to the master cylinder when we compressed the piston to a more open position. You will need to pump your brake pedal six to ten times to rebuild pressure on your brakes.
After you feel pressure in your brake pedal again, release your parking brake, put your vehicle in gear and move forward slowly. Press your brakes to ensure stopping works. Now continue driving nearby with several tests of your brakes to make sure all is well. Test the brakes in both forward and reverse. It will take a few drives to seat the pads on the rotors so try to avoid excessively hard braking for the first 10 to 20 miles.
Congratulations! You have just replaced your brake pads. Simply repeat this process for your other wheels. Once you have all of your tools and equipment ready, this should only take between 15 and 30 minutes.