How To Change Brakes In A Car?

Changing your car's brakes is a crucial maintenance task that ensures your safety on the road. While it might seem daunting, with the right tools, knowledge, and a bit of patience, you can save money by doing it yourself. This guide will provide a comprehensive walkthrough of the process, covering everything from preparation to troubleshooting.

Table of Contents

Detailed Explanations

Preparation

Before you even think about touching your car, safety is paramount. Park your car on a level surface, engage the parking brake, and use wheel chocks behind the rear wheels (if working on the front) or in front of the front wheels (if working on the rear). Gather all the necessary tools: a jack, jack stands (never work under a car supported only by a jack), a lug wrench, a socket set (metric or SAE depending on your car), brake cleaner, gloves, and safety glasses. A repair manual specific to your car model is invaluable for torque specifications and specific instructions. Understanding your car's specific brake system is crucial; different models may have slightly different procedures.

Diagnosis

Knowing when to replace your brakes is critical. Common symptoms of worn-out brakes include:

• Squealing or grinding noises: This often indicates worn-down brake pads.
• Pulsating brake pedal: This can be a sign of warped rotors.
• Reduced braking performance: If your car takes longer to stop, your brakes may need replacement.
• Visual inspection: Check the thickness of your brake pads. If they are less than 1/4 inch thick, they need replacing. Examine the rotors for deep grooves or excessive rust.

Disassembly

1. Loosen the lug nuts: Before jacking up the car, use the lug wrench to loosen the lug nuts on the wheel you're working on. Don't remove them completely, just break them free.
2. Jack up the car: Consult your car's owner's manual for the correct jacking points. Place the jack under the designated point and raise the car until the tire is off the ground.
3. Secure with jack stands: Immediately place jack stands under the car's frame near the jacking point. Never work under a car supported only by a jack.
4. Remove the wheel: Fully unscrew the lug nuts and remove the wheel.
5. Locate the caliper bolts: These bolts hold the brake caliper to the caliper bracket. They are usually located on the back of the caliper.
6. Remove the caliper bolts: Use a socket wrench to remove the caliper bolts. You may need to use penetrating oil if they are seized.
7. Remove the caliper: Carefully slide the caliper off the rotor. Be careful not to damage the brake hose. Never let the caliper hang by the brake hose. Use a caliper hanger (or a piece of wire) to support the caliper.
8. Remove the brake pads: The brake pads are usually held in place by clips or pins. Remove these clips or pins and slide the brake pads out of the caliper bracket.
9. Remove the caliper bracket (if necessary): If you are replacing the rotors, you will need to remove the caliper bracket. This is usually held in place by two bolts on the back of the steering knuckle. Use a socket wrench to remove these bolts.

Inspection

Once the brake components are disassembled, thoroughly inspect each part:

• Brake pads: Measure the thickness of the brake pads. If they are less than 1/4 inch thick, they need replacing. Also, check for uneven wear.
• Rotors: Check the rotors for deep grooves, cracks, or excessive rust. Measure the rotor thickness with a micrometer. If the rotor is below the minimum thickness specified in your repair manual, it needs replacing. Also, check for rotor runout (warping) using a dial indicator.
• Caliper: Inspect the caliper for leaks or damage. Check the caliper pistons to make sure they move freely. If the caliper is leaking or the pistons are seized, it needs replacing or rebuilding.
• Brake lines and hoses: Inspect the brake lines and hoses for leaks, cracks, or bulges. If any damage is found, replace the affected component.

Component Replacement

• Brake Pads: Install the new brake pads into the caliper bracket. Ensure they are seated correctly and secured with the clips or pins. Apply a small amount of brake grease to the back of the brake pads where they contact the caliper pistons and the caliper bracket. This helps prevent squealing.
• Rotors (if necessary): Clean the new rotors with brake cleaner to remove any manufacturing oils. Slide the rotor onto the wheel studs. Secure it temporarily with a lug nut.
• Caliper: If necessary, compress the caliper piston back into the caliper. This may require a special caliper piston compression tool. Be careful not to damage the piston. Slide the caliper over the new brake pads and rotor. Align the caliper with the caliper bracket and install the caliper bolts. Tighten the caliper bolts to the torque specifications in your repair manual. Use a torque wrench to ensure proper tightening.
• Caliper Hardware (if necessary): Replace any worn or damaged caliper hardware, such as slide pins or bushings. Lubricate the slide pins with brake grease before installation.

Assembly

1. Reinstall the caliper bracket (if removed): If you removed the caliper bracket, reinstall it and tighten the bolts to the torque specifications in your repair manual.
2. Reinstall the caliper: Slide the caliper over the new brake pads and rotor. Align the caliper with the caliper bracket and install the caliper bolts.
3. Tighten the caliper bolts: Tighten the caliper bolts to the torque specifications in your repair manual. Use a torque wrench to ensure proper tightening.
4. Reinstall the wheel: Place the wheel back onto the hub and tighten the lug nuts by hand.
5. Lower the car: Carefully lower the car back to the ground.
6. Torque the lug nuts: Use a torque wrench to tighten the lug nuts to the torque specifications in your car's owner's manual. Tighten the lug nuts in a star pattern to ensure even pressure.

Brake Bleeding

Brake bleeding is essential after replacing brake components to remove air from the brake lines. Air in the lines can cause a spongy brake pedal and reduced braking performance.

1. Locate the bleeder screws: The bleeder screws are located on the brake calipers.
2. Attach the tubing: Attach one end of the clear tubing to the bleeder screw. Place the other end of the tubing into a jar or container filled with a small amount of brake fluid. This prevents air from being sucked back into the system.
3. Open the bleeder screw: Have an assistant slowly depress the brake pedal. While the pedal is depressed, open the bleeder screw.
4. Close the bleeder screw: Before the pedal reaches the floor, close the bleeder screw.
5. Release the brake pedal: Have your assistant slowly release the brake pedal.
6. Repeat the process: Repeat steps 3-5 until no more air bubbles come out of the tubing.
7. Tighten the bleeder screw: Tighten the bleeder screw to the torque specifications in your repair manual.
8. Repeat on all calipers: Repeat the bleeding process on all four calipers, starting with the caliper furthest from the master cylinder (usually the rear passenger side).
9. Check the brake fluid level: After bleeding all the calipers, check the brake fluid level in the master cylinder. Add brake fluid as needed to bring it up to the "MAX" line.

Important Note: Use the correct type of brake fluid as specified in your car's owner's manual (usually DOT 3 or DOT 4). Never mix different types of brake fluid.

Testing and Bedding

After replacing your brakes, it's crucial to test them in a safe area and properly bed in the new brake pads.

1. Test the brakes: Start the car and slowly drive forward. Gently apply the brakes to ensure they are working properly. Check for any unusual noises or vibrations.
2. Bed in the brake pads: The bedding-in process helps transfer brake pad material to the rotor, creating optimal braking performance. A common bedding-in procedure involves performing several moderate stops from 30 mph to 10 mph, followed by several harder stops from 50 mph to 20 mph. Allow the brakes to cool down between stops. Consult your brake pad manufacturer's instructions for specific bedding-in procedures.
3. Avoid hard braking: During the first few hundred miles after replacing your brakes, avoid hard braking unless absolutely necessary.

Troubleshooting

• Squealing brakes: This can be caused by a number of factors, including low-quality brake pads, dirty rotors, or improper installation. Try applying brake grease to the back of the brake pads. If the squealing persists, you may need to replace the brake pads with a higher-quality brand.
• Grinding brakes: This usually indicates that the brake pads are completely worn down and the metal backing plate is rubbing against the rotor. This can damage the rotors and should be addressed immediately.
• Spongy brake pedal: This is usually caused by air in the brake lines. Bleed the brakes to remove the air.
• Pulsating brake pedal: This can be a sign of warped rotors. Replace the rotors.
• Brake caliper won't compress: The caliper piston may be seized. Try using a caliper piston compression tool to compress the piston. If the piston is still seized, you may need to replace or rebuild the caliper.
• Bleeder screw is seized: Apply penetrating oil to the bleeder screw and let it soak for a few minutes. Then, try using a wrench to loosen the bleeder screw. If the bleeder screw is still seized, you may need to replace the caliper.

Frequently Asked Questions

• How often should I change my brakes? Brake life depends on driving habits, but typically, brake pads last 30,000-70,000 miles, and rotors last 50,000-100,000 miles. Listen for noises and inspect them regularly.

• Can I just replace the brake pads and not the rotors? Yes, if the rotors are still within the manufacturer's specifications for thickness and runout and are not severely damaged. However, it's often recommended to replace both together for optimal performance.

• What type of brake fluid should I use? Use the type of brake fluid specified in your car's owner's manual, usually DOT 3 or DOT 4. Never mix different types of brake fluid.

• Do I need to bleed the brakes after replacing brake pads? While not always strictly necessary if you only replaced the pads and didn't open the hydraulic system, it's generally recommended to bleed the brakes to ensure optimal performance and remove any potential air bubbles.

• How much does it cost to have a mechanic change my brakes? The cost varies depending on the car model and the mechanic's labor rates, but typically ranges from $300 to $800 per axle (front or rear).

Conclusion

Changing your car's brakes is a manageable task with the right preparation, tools, and knowledge. Remember to prioritize safety, follow the steps carefully, and consult your car's repair manual for specific instructions. Regular brake maintenance is vital for safe driving.