Tools and materials:
- Replacement brake pads and any hardware that comes with them
- Jack and jack stands
- Lug nut tire tool
- Socket set with ratchet (open-end wrenches also work)
- Stout, straight-edged screwdriver
- Hammer and punch
- Pliers
- Pry bar (tire tools also work)
- Wire brush
- Aerosol brake cleaner
- Brake fluid (just in case)
- Thread-locking compound
- Five-gallon pail or other waterproof container of similar size
- Rags to catch fluid spills under master cylinder
- Inexpensive turkey baster
Unfortunately, all disc brake systems are not the same. But they are similar enough that we can generalize quite a bit here. The two main types are fixed calipers and moving calipers ("floating" or "sliding"). Fixed calipers are the easiest, as you do not have to remove the caliper to get to the pads. After disconnecting any electrical wear sensors, remove a small pin or spring clip and pull out the pads with a pair of pliers. Some of these systems have the pads secured by a pin that must be driven out with a hammer and punch; most systems are no longer of this simpler type. With moving calipers, the caliper is either removed or flipped up, rotating on the top pin, which is left in place.
How-to tips
If the brake fluid was topped off when the pads were worn, there may be too much fluid in the system to support the new, thicker pads. Leaks can occur under the hood. Some fluid can be drained from the reservoir with a vacuum pump or simply with a turkey baster. Or you can use rags under the master cylinder to catch minor spills. Loosen the reservoir's cap and proceed to the first wheel.
Whether you are servicing the front or rear of the vehicle, you should do both sides, never just one. But do them from start to finish – one at a time. The first reason for doing one at a time is so you can more effectively monitor the fluid level as you work. You’ll find out the second reason soon. Make sure to secure the vehicle in position and remove the lug nuts (both wheels). After the vehicle is jacked up and stable on the jack stands, finish loosening the lug nuts and remove the first rim. Now you can really get started. For vehicle-specific brake pad replacement procedures, always consult a service manual.
The general procedures for most systems are as follows:
1. Disconnect any electrical wear sensors.
2. Using a socket wrench, remove the two long guide pins ("slider bolts"), usually accessed on the back of the caliper. On front wheels, they are easier to see if you turn the steering wheel toward the other side of the vehicle. To loosen the caliper, you may need to pry it slightly with a sturdy screwdriver. Again, with some systems, you may be able to remove only the bottom pin and flip the caliper up over the top pin. But whether you flip it up or remove the caliper, take care not to stress the brake hose. If removing the caliper, use the five-gallon pail, inverted, to support the weight of the caliper.
3. The pads are now exposed. If present, remove any clips, anti-rattle springs and anti-squeal shims. Some pads have tabs that are bent over. You may need to straighten them with pliers before removal. And now the second reason for doing the brakes one side at a time: You have the other side to refer to if you lose track of where any of the hardware came from.
4. Remove the old pads with pliers or a light hammer tap.
5. Dust the caliper sliding area with a wire brush and spray brake cleaner. Note: Never use high-pressure, compressed air on brake dust, as it contains asbestos and should not be inhaled.
6. Lightly lubricate the same area with heat-resistant brake grease. Be careful with the lubricant, not allowing any of it to come into contact with the swept area of the rotor, or getting any on the new brake pads.
7. If your system is equipped with hardware such as clips, they should be included with your new pads, especially if you get Original Equipment Manufacturer (OEM) parts. There may also be a packet of grease.
8. With the old pads out, the internal pistons are exposed. They need to be retracted back into the caliper. Your vehicle may have two pistons. If so, be sure to compress them both at the same time. Pressing one could pop the other all the way out, which is a bad thing. Reposition one old pad back into place and tighten the large C-clamp on it to retract the pistons. You can also use a piece of two-by-four and a pry bar to push them back. Or, if you only have one piston, just use a pry bar with a rag around the end. The piston(s) need to be fully retracted to fit over the rotor, but take care not to damage their rubber seals.
9. Compression of the piston into its bore forces fluid back into the master cylinder's reservoir. This is when leakage may occur if too much is in the system for the new, thicker pads. Check the reservoir, particularly after you finish the first wheel. You should be able to tell if the second wheel is likely to force too much fluid into the reservoir, so you can remove some fluid ahead of time.
10. Insert the new pads, replacing any hardware you removed with new parts, if available. If yours are the bent-tab style of pads, you have to ensure a snug fit. If it is not snug, adjust the tab lightly with a hammer until you have a tight fit.
11. Reposition the caliper over the rotor and secure it with the long guide pins. Use a thread-locking compound on the pins' threaded area to ensure a secure fit.
12. Reconnect any electrical wear sensors. Now refer back to step one on this list to start work on the second wheel. Once the second wheel also has new pads, please proceed to step 13.
13. When finished, pump the brake pedal several times to seat the new pads. The brakes won't stop the vehicle until the pads are properly seated. Recheck the reservoir for proper fluid level and adjust.
14. Install wheels and tighten the lug nuts to just snug.
15. Lower the vehicle and fully tighten the lug nuts. Note: You must use a torque wrench to properly tighten your lug nuts. The ft-lbs specification necessary for your vehicle will be located in the owner’s manual.
16. It’s time for a road test. Remember, don’t forget to seat your new pads or to properly tighten lug nuts before driving off.
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