How to Change Brake Pads
Changing your vehicle's brake pads is a fundamental maintenance task that can save you a significant amount of money and provide a great sense of accomplishment. While brakes are a critical safety system, the process of replacing the pads is a manageable DIY project for someone with basic mechanical aptitude, the right tools, and a methodical approach. This guide will provide a comprehensive, step-by-step walkthrough of the entire process, from gathering the necessary tools to properly bedding in the new pads, ensuring you can perform the job safely and effectively.
Safety First: The Non-Negotiable Priority
Before touching a single tool, your primary focus must be on safety. Working on your brakes means you are responsible for a system that is vital for the safety of you, your passengers, and others on the road. Never compromise on safety procedures. If you are unsure or uncomfortable with any step, stop and consult a professional mechanic.
The absolute essentials for safe brake work include:
- Jack Stands: Never rely solely on a car jack to support the vehicle while you are working under it. Always use sturdy, rated jack stands placed on solid, level ground. The jack should only be used for lifting the vehicle, not for holding it.
- Wheel Chocks: Always chock the wheels opposite to the end you are working on. For example, if you are lifting the front of the car, chock both rear wheels to prevent the vehicle from rolling.
- Safety Glasses: Brake components are often coated in fine, harmful dust. Wear safety glasses to protect your eyes from this debris and from any accidental sprays of brake cleaner.
- Gloves: Durable mechanics gloves protect your hands from sharp edges, hot components, and chemicals.
Gathering the Necessary Tools and Materials
Having the correct tools before you start will make the job smoother and safer. You do not need an expensive, professional-grade toolbox, but a specific set of tools is required.
Essential Tools:
- Lug Wrench/Wheel Nut Wrench: To remove the wheel.
- Floor Jack: For lifting the vehicle.
- Jack Stands (at least two): For supporting the vehicle.
- C-Clamp or Brake Caliper Piston Tool: This is crucial for compressing the caliper piston back into its housing to make room for the new, thicker brake pads. A large C-clamp is often sufficient, but a dedicated piston tool is better for certain caliper designs.
- Socket Set and Ratchet: A standard 3/8-inch drive socket set with various sizes is essential. You will need a socket that fits your lug nuts and typically a smaller socket or Allen key for the caliper bolts.
- Wrench Set: Combination wrenches (open-end on one side, box-end on the other) are useful for holding the pin on the caliper bolts while loosening the nut.
- Brake Cleaner: Aerosol brake cleaner is mandatory for thoroughly cleaning the caliper, bracket, and other components without leaving a residue.
- Torque Wrench: This is highly recommended. Properly torquing the lug nuts and caliper bolts is critical for safety. Overtightening can damage components, and undertightening can lead to catastrophic failure.
- Piston Retraction Tool (for rear brakes with integrated parking brakes): If you are working on rear brakes that also function as the parking brake, a simple C-clamp will not work. You will need a specific tool that screws the piston back in as it compresses it.
- Brake Grease/Lubricant: Special high-temperature brake grease is used on the back of the brake pads, on shims, and on contact points between the pads and caliper to prevent squealing.
Materials:
- New Brake Pads: Ensure you purchase the correct brake pads for your specific vehicle's make, model, and year.
- Optional - New Rotors: If your brake rotors are worn, warped, or scored beyond specification, you should replace them at the same time. It is often recommended to install new rotors with new pads.
- Optional - New Brake Hardware: Many brake pad kits include new clips, shims, and anti-rattle springs. It is good practice to replace these to ensure optimal performance and quiet operation.
Understanding Your Brake System: The Disc Brake Assembly
Most modern vehicles use disc brakes on the front wheels, and many on all four wheels. The key components you will interact with are:
- Brake Rotor (Disc): The large, flat, metal disc that spins with the wheel.
- Brake Caliper: The assembly that straddles the rotor. It contains the pistons.
- Brake Pads: The friction material that is pressed against the rotor by the caliper to create stopping power. They are mounted inside the caliper.
Step-by-Step Guide to Changing Brake Pads
Follow these steps carefully. It is often best to work on one side at a time, using the other side as a reference if you get confused during reassembly.
Step 1: Preparation
Park your car on a flat, solid surface like a driveway or garage floor. Engage the parking brake. Put on your safety glasses and gloves. Loosen the lug nuts on the wheel you plan to work on first by about a quarter-turn while the car is still on the ground. Do not remove them completely.
Step 2: Lifting and Securing the Vehicle
Place the wheel chocks securely against the tires on the opposite end of the car. Position the floor jack under the vehicle's designated lift point (consult your owner's manual for the exact location, usually a reinforced seam behind the front wheel or ahead of the rear wheel). Lift the vehicle until the tire is clear of the ground. Slide the jack stand under a solid chassis point, such as a frame rail or designated jack point, and lower the vehicle onto the jack stand. Double-check that the vehicle is stable on the jack stand before proceeding. You can leave the floor jack lightly touching as a secondary safety measure.
Step 3: Removing the Wheel and Inspecting the Brakes
Now you can fully remove the loosened lug nuts and take the wheel off. Set it aside safely under the car for an extra layer of security. You now have a clear view of the brake caliper and rotor. Take a moment to inspect the assembly. Note how the caliper is mounted.
Step 4: Removing the Brake Caliper
There are typically two main bolts that hold the caliper in place. These may be located on the front or back of the caliper. Using your socket set or wrench, carefully remove these two bolts. Be careful not to strain the brake hose connected to the caliper. Once the bolts are out, the caliper assembly can be lifted off the rotor. Do not let it hang by the brake hose. Suspend it from a suspension component using a piece of wire or a bungee cord to avoid damaging the flexible hose.
Step 5: Removing the Old Brake Pads and Hardware
With the caliper out of the way, the old brake pads will be visible, sitting in the caliper bracket. They may be held in by clips, pins, or springs. Carefully note how they are positioned and how the hardware fits together. Taking a picture with your phone at this stage is highly recommended. Remove the old pads and the old hardware clips from the caliper bracket.
Step 6: Compressing the Caliper Piston
Before you can install the new, thicker brake pads, you must push the caliper piston back into its bore to create clearance. Place the old brake pad against the piston. Then, use your C-clamp or piston tool, with one end on the back of the piston (through the pad) and the other on the back of the caliper body. Slowly and steadily tighten the clamp until the piston is fully retracted. If you are working on a rear caliper with an integrated parking brake, you will need the special tool that screws the piston in as it retracts. As you compress the piston, you will see the brake fluid level in the master cylinder reservoir (under the hood) rise slightly. It is a good idea to check the reservoir and, if necessary, use a turkey baster to remove some fluid to prevent it from overflowing. Do not let the reservoir run dry, as this will introduce air into the brake lines.
Step 7: Preparing the New Brake Pads and Hardware
Thoroughly clean the caliper bracket and the areas where the new pads will sit using brake cleaner and a wire brush. Any built-up rust or debris can cause the pads to stick or make noise. Apply a thin layer of high-temperature brake grease to the back plates of the new brake pads (where they contact the caliper piston and bracket), on the shims, and on the metal tabs that slide into the bracket. Avoid getting any grease or oil on the friction surface of the brake pads or the rotor.
Step 8: Installing the New Brake Pads and Hardware
Install the new hardware clips into the caliper bracket. Then, slide the new brake pads into their correct positions within the bracket. They should slide in smoothly but fit snugly.
Step 9: Reinstalling the Brake Caliper
Carefully lift the caliper back over the rotor and align it with the mounting points. Slide the caliper bolts back through and hand-tighten them. Once they are started, use your socket wrench to tighten them securely. For final safety, you must use a torque wrench to tighten these bolts to your vehicle's manufacturer specification, which can be found in a service manual or online database.
Step 10: Repeating the Process and Reassembling
If you are replacing pads on both sides at the same axle, repeat Steps 3 through 9 on the other side of the vehicle. Once both sides are complete, remount the wheel and hand-tighten the lug nuts. Carefully lift the vehicle off the jack stands, lower it completely to the ground, and then use a torque wrench to tighten the lug nuts in a star pattern to the manufacturer's specified torque. This ensures the wheel is seated evenly.
Step 11: The Critical Bedding-In Process
Your new brake pads will not perform optimally until they are properly bedded-in. This process transfers a thin, even layer of pad material onto the rotor surface. Drive to a safe, open area with little traffic. Accelerate to about 45 mph and then gently brake down to about 10 mph. Do not come to a complete stop. Repeat this process 5 to 10 times, allowing about 30 seconds of driving between cycles for the brakes to cool slightly. This generates the necessary heat to condition the pads and rotors. Avoid hard, aggressive braking for the first few hundred miles.
When to Seek Professional Help
While this is a DIY-friendly project, there are situations where professional assistance is warranted:
- If you notice any significant brake fluid leaks from the caliper or brake lines.
- If the brake pedal feels spongy or sinks to the floor after the job, indicating air may be in the brake lines, requiring a brake system bleed.
- If you encounter severely rusted or seized components that you cannot safely remove.
- If you are not confident in any part of the process.
Conclusion
Learning how to change brake pads is an empowering skill that combines savings with practical knowledge. By following this detailed guide, prioritizing safety at every step, and using the correct tools and procedures, you can successfully maintain this vital system. The confidence gained from performing this task correctly will extend to other areas of vehicle maintenance, making you a more informed and capable car owner. Remember that a well-maintained brake system is not just about performance; it is the foundation of your safety on the road.