How To Replace Brake Discs And Pads?

Replacing your brake discs and pads is a crucial maintenance task that ensures your vehicle's safety and performance. While it's often entrusted to professional mechanics, with the right tools, knowledge, and patience, it's a job you can tackle yourself, saving money and gaining a valuable understanding of your car's braking system. This guide provides a detailed, step-by-step approach to safely and effectively replace your brake discs and pads.

Essential Information at a Glance

Detailed Explanations

Tools Required

Having the right tools is crucial for a successful and safe brake replacement. Here's a comprehensive list:

• Jack and Jack Stands: A sturdy jack is essential to lift the vehicle, and jack stands are absolutely necessary to safely support it while you work. Never work under a vehicle supported only by a jack.
• Wheel Chocks: Place these behind the wheels opposite the ones you're working on to prevent the vehicle from rolling.
• Lug Wrench: To loosen and remove the wheel nuts.
• Socket Set: Including sockets that fit your caliper bolts and brake bleed screws. Metric sizes are most common.
• Wrench Set: For various fasteners in the brake system.
• Brake Caliper Piston Compressor Tool: This tool is essential for pushing the caliper piston back into the caliper body to accommodate the new, thicker brake pads. There are various types, including screw-type and lever-type compressors.
• Brake Cleaner: To clean brake components before and after installation.
• Wire Brush: To clean rust and debris from the hub surface where the brake disc sits.
• Torque Wrench: To tighten lug nuts and caliper bolts to the manufacturer's specified torque. Overtightening can damage components, while undertightening can be dangerous.
• Gloves: To protect your hands from dirt, grease, and brake dust.
• Safety Glasses: To protect your eyes from debris.
• Penetrating Oil: To loosen stubborn bolts.
• Brake Fluid: Use the correct type for your vehicle (DOT 3, DOT 4, or DOT 5.1). Refer to your owner's manual.
• Brake Bleeder Kit (Optional): While not always necessary, a brake bleeder kit can make bleeding the brakes easier.
• Hammer (Optional): For gently tapping the brake disc to loosen it from the hub if it's stuck.
• Rags or Paper Towels: For cleaning up spills and wiping down components.
• Service Manual (Recommended): Your vehicle's service manual provides specific instructions and torque specifications for your make and model.

Safety Precautions

Safety is paramount when working on your vehicle's brakes. Adhering to these precautions can prevent serious injury:

• Always work on a level surface.
• Engage the parking brake.
• Use wheel chocks behind the wheels opposite the ones you're working on.
• Never work under a vehicle supported only by a jack. Use jack stands. Ensure the jack stands are placed on designated jacking points on the vehicle's frame.
• Wear safety glasses to protect your eyes from brake dust and debris.
• Wear gloves to protect your hands from brake fluid and dirt.
• Work in a well-ventilated area. Brake dust can be harmful if inhaled.
• Dispose of old brake pads and fluid properly. Brake fluid is corrosive and harmful to the environment.
• If you are unsure about any step of the process, consult a qualified mechanic.

Step-by-Step Procedure

This is a general guide; always refer to your vehicle's service manual for specific instructions.

1. Preparation:

   • Gather all the necessary tools and parts.
   • Park the vehicle on a level surface, engage the parking brake, and chock the rear wheels.
   • Loosen the lug nuts on the wheel you'll be removing, but don't remove them completely yet.

2. Lifting the Vehicle:

   • Place the jack under the designated jacking point for that wheel.
   • Raise the vehicle until the tire is off the ground.
   • Immediately place a jack stand under the frame near the jacking point.
   • Slowly lower the vehicle onto the jack stand.
   • Remove the wheel.

3. Removing the Old Brake Pads and Caliper:

   • Locate the caliper bolts (usually two bolts on the back of the caliper).
   • Use a wrench or socket to remove the caliper bolts. You may need penetrating oil if they are seized.
   • Carefully slide the caliper off the brake disc. Be careful not to damage the brake hose. If necessary, suspend the caliper with a bungee cord or wire to prevent strain on the hose.
   • Remove the old brake pads from the caliper bracket. Note their orientation for reassembly.

4. Removing the Caliper Bracket (If Necessary):

   • In some cases, you may need to remove the caliper bracket to access the brake disc.
   • Locate the bracket bolts (usually larger than the caliper bolts).
   • Remove the bracket bolts.

5. Removing the Old Brake Disc:

   • If the brake disc is stuck, use a hammer to gently tap the back of the disc near the hub. Avoid hitting the disc face.
   • You may need to use penetrating oil on the hub to loosen the disc.
   • Once loose, carefully pull the brake disc off the hub.

6. Cleaning and Inspection:

   • Use a wire brush to clean any rust or debris from the hub surface where the new brake disc will sit. A clean surface is crucial for proper disc seating.
   • Inspect the brake caliper and brake hose for any signs of damage or leaks. Replace them if necessary.

7. Installing the New Brake Disc:

   • Carefully slide the new brake disc onto the hub.
   • Ensure the disc sits flush against the hub surface.

8. Installing the Caliper Bracket (If Removed):

   • Reinstall the caliper bracket and tighten the bolts to the manufacturer's specified torque using a torque wrench.

9. Installing the New Brake Pads:

   • Install the new brake pads into the caliper bracket, ensuring they are in the correct orientation. Refer to the notes you made when removing the old pads.
   • Apply a thin layer of brake lubricant to the back of the brake pads where they contact the caliper piston and bracket. This helps prevent squealing.

10. Compressing the Caliper Piston:

    • Use a brake caliper piston compressor tool to push the caliper piston back into the caliper body. This creates enough space for the new, thicker brake pads.
    • Some calipers require a special tool to rotate the piston while compressing it. Consult your vehicle's service manual.

11. Reinstalling the Caliper:

    • Carefully slide the caliper over the new brake pads and onto the brake disc.
    • Reinstall the caliper bolts and tighten them to the manufacturer's specified torque using a torque wrench.

12. Repeat on the Other Side:

    • Repeat steps 2-11 on the other wheel on the same axle. Always replace brake discs and pads in pairs (both sides of the axle) to ensure even braking.

13. Bleeding the Brakes (If Necessary):

    • If you disconnected the brake hose or suspect air has entered the system, you will need to bleed the brakes.
    • Open the brake bleed screw on the caliper.
    • Have an assistant slowly pump the brake pedal several times, then hold it down.
    • With the pedal held down, close the bleed screw.
    • Repeat this process until clear, bubble-free brake fluid comes out of the bleed screw.
    • Important: Keep the brake fluid reservoir topped up throughout the bleeding process to prevent air from entering the system.
    • Tighten the bleed screw to the manufacturer's specified torque.

14. Reinstalling the Wheel:

    • Reinstall the wheel.
    • Hand-tighten the lug nuts.
    • Lower the vehicle back to the ground.
    • Use a torque wrench to tighten the lug nuts to the manufacturer's specified torque. Tighten them in a star pattern to ensure even pressure.

15. Bedding In the New Brakes:

    • Bedding in is crucial for optimal brake performance.
    • Find a safe, open area with no traffic.
    • Perform several moderate stops from 30 mph to 10 mph.
    • Then, perform several harder stops from 50 mph to 10 mph.
    • Allow the brakes to cool down completely between each set of stops.
    • Avoid hard braking for the first few hundred miles.

Choosing the Right Parts

Selecting the right brake discs and pads is essential for safety and performance. Consider these factors:

• Vehicle Compatibility: Ensure the parts are specifically designed for your make, model, and year of vehicle.
• Driving Style: If you drive aggressively or tow frequently, consider performance-oriented brake pads and discs.
• Material: Brake pads are available in various materials, including organic, semi-metallic, and ceramic. Each material has its own advantages and disadvantages in terms of braking performance, noise, and dust.
• Brand Reputation: Choose reputable brands known for quality and reliability.
• Reviews: Read online reviews to get feedback from other users.

Bedding In New Brakes

Bedding in new brakes is the process of transferring a thin layer of brake pad material onto the brake disc surface. This creates a more uniform contact area and improves braking performance. Follow the procedure outlined in step 15 of the "Step-by-Step Procedure" section.

Troubleshooting

Here are some common problems encountered during brake replacement and their solutions:

• Stuck Caliper Bolts: Use penetrating oil and a breaker bar to loosen stubborn bolts. If necessary, apply heat with a torch (use caution).
• Stuck Brake Disc: Use a hammer to gently tap the back of the disc near the hub. Use penetrating oil. A brake disc puller can also be used.
• Difficulty Compressing the Caliper Piston: Ensure you are using the correct type of caliper piston compressor tool. Some calipers require a special tool to rotate the piston while compressing it.
• Brake Squeal: Apply brake lubricant to the back of the brake pads where they contact the caliper piston and bracket. Ensure the brake discs are clean and free of rust.
• Soft Brake Pedal: Bleed the brakes to remove any air from the system. Check for leaks in the brake lines.

Cost Considerations

DIY brake replacement can save you money compared to professional service. Here's a breakdown of estimated costs:

• Brake Discs: $50 - $200 per disc (depending on quality and brand)
• Brake Pads: $20 - $100 per set (depending on material and brand)
• Brake Fluid: $10 - $20
• Tools (if needed): $50 - $200 (initial investment, but reusable for future jobs)

Professional brake replacement can cost $300 - $800 or more per axle, including parts and labor.

Frequently Asked Questions

• How often should I replace my brake discs and pads? Brake disc and pad replacement intervals vary depending on driving habits and vehicle type, but typically every 30,000 to 70,000 miles. Regular inspections are crucial.

• How do I know if my brake discs need replacing? Signs include squealing or grinding noises, vibrations during braking, reduced braking performance, and visible scoring or damage on the disc surface.

• Can I just replace the brake pads and not the discs? If the brake discs are within the manufacturer's specified thickness and are not warped or damaged, you may be able to replace only the pads. However, it's generally recommended to replace both at the same time for optimal performance.

• What type of brake fluid should I use? Use the type of brake fluid specified in your vehicle's owner's manual (DOT 3, DOT 4, or DOT 5.1). Mixing different types of brake fluid can damage your braking system.

• Is it safe to drive with worn brakes? Driving with worn brakes is extremely dangerous and can significantly increase your stopping distance. Replace your brakes as soon as you notice any signs of wear.

• Do I need to bleed the brakes after replacing pads? Bleeding is usually not necessary if you only replace the pads and do not open the brake lines. However, if the brake pedal feels spongy after the replacement, bleeding is recommended.

Conclusion

Replacing your brake discs and pads is a manageable DIY project with the right tools and knowledge. Remember to prioritize safety, follow the steps carefully, and consult your vehicle's service manual for specific instructions.