1. Safety First!
* Wear safety glasses: Brake fluid is corrosive.
* Use gloves: Brake fluid can irritate skin.
* Work in a well-ventilated area: Brake cleaner fumes are harmful.
2. Necessary Tools:
* C-clamp or brake caliper piston compression tool: This is the most important tool. A C-clamp works in a pinch, but a purpose-built tool is safer and better designed.
* Socket wrench and socket that fits the caliper's bleeder valve.
* Wrench to remove caliper bolts.
* Brake cleaner: To clean the caliper piston and bore.
* Rags or shop towels: To clean up brake fluid spills.
* Optional: A helper to assist with applying pressure.
3. Steps:
* Open the bleeder valve: This allows air to escape as you compress the piston, preventing damage to the caliper and making it easier to push the piston back in. Loosen it slightly, don't remove it completely. You'll need to use a wrench and an appropriate sized socket that fits the bleed screw.
* Clean the piston and bore: Spray the piston and the inside of the caliper bore thoroughly with brake cleaner. Let it dry completely. This will remove any dirt or debris that might scratch the piston or prevent it from seating properly.
* Compress the piston: Using your C-clamp or compression tool, carefully and slowly push the piston back into the bore. Apply even pressure to avoid bending or damaging the piston. Do not force it. If it's difficult, double-check that the bleeder valve is slightly open and that the piston is clean.
* Check for smooth travel: As you compress the piston, periodically check for smooth, even travel. It should slide in evenly without sticking. If it binds, stop and investigate. There might be corrosion or debris you missed.
* Close the bleeder valve: Once the piston is fully seated, tighten the bleeder valve securely.
* Reinstall the caliper: Once the piston is fully seated and the bleeder valve is closed, reinstall the caliper onto the brake bracket, tightening the bolts to the manufacturer's specified torque.
Important Considerations:
* Hydraulic System: Remember, the brake system is hydraulic. Pushing the piston back in will force brake fluid back through the lines. That's why opening the bleeder valve is crucial. If you don't open the bleeder valve, you risk damaging the caliper or ABS system.
* Damaged Piston: If the piston is damaged (scored, bent, or seized), it will need to be replaced. Forcing a damaged piston could further damage the caliper.
* Type of Caliper: Some calipers might have more than one piston. Make sure you understand how the caliper works and push both pistons back evenly.
* Torque Specifications: Always refer to your car's repair manual for the correct torque specifications for the caliper bolts. Over-tightening can damage the caliper.
If you're not comfortable performing this repair, it's best to take your vehicle to a qualified mechanic. Incorrectly installing a brake caliper can lead to brake failure, which is extremely dangerous.
