Here's a general outline. Specific steps might vary slightly depending on your Focus's trim level and options:
Tools You'll Need:
* Jack and Jack Stands: Absolutely essential for safety. Never work under a car supported only by a jack.
* Lug Wrench: To remove the wheels.
* Wheel Chocks: For added safety.
* Socket Wrench Set: Including metric sockets (sizes will vary, consult your owner's manual or a repair manual). You'll need sockets for caliper bolts, rotor retaining bolts (if any), and possibly lug nuts.
* Torque Wrench: Crucial for tightening bolts to the manufacturer's specified torque. Improper torque can damage components.
* C-Clamp or Caliper Compressor Tool: To compress the caliper piston.
* Wire or Zip Tie: To hold the caliper out of the way.
* Brake Cleaner: To clean the hub and rotor mating surfaces.
* Penetrating Oil (like PB Blaster): To help loosen rusted or stuck bolts.
* Gloves: To protect your hands.
* Safety Glasses: To protect your eyes.
* Repair Manual (highly recommended): A specific repair manual for your 2003 Ford Focus will provide detailed instructions and torque specifications.
Procedure:
1. Safety First: Park on a level surface, engage the parking brake, and use wheel chocks on the rear wheels.
2. Raise and Secure the Vehicle: Use the jack to lift the front of the car, then securely position jack stands under the frame near the jacking points (consult your owner's manual for location).
3. Remove the Wheel: Loosen the lug nuts slightly with the lug wrench before jacking up the car. Once lifted, remove the lug nuts completely and take off the wheel.
4. Remove the Caliper: Locate the caliper bolts (usually two) and use the socket wrench to remove them. You may need penetrating oil to loosen them. Carefully support the caliper as you remove it. Do not let the brake line hang. You can use a wire or zip tie to secure it to something nearby to keep it out of the way and prevent stressing the brake line.
5. Compress the Caliper Piston: Use a C-clamp or caliper compressor tool to slowly push the caliper piston back into the caliper. This creates space to remove the rotor. You may need to rotate the piston as you push to help it retract evenly.
6. Remove the Rotor: Some rotors have a retaining bolt or screw on the back; remove this if present. Carefully slide the rotor off the hub. It might be stuck on due to rust, so use gentle force and avoid damaging the wheel studs. If it's really stuck, use a rubber mallet to tap it gently.
7. Clean the Hub: Thoroughly clean the hub mounting surface with brake cleaner. Remove any rust or debris.
8. Install the New Rotor: Slide the new rotor onto the hub, ensuring it seats properly. Replace the retaining bolt (if applicable) and tighten it to the manufacturer's specified torque.
9. Reinstall the Caliper: Make sure the caliper slides freely. Install the caliper bolts and tighten them to the manufacturer's specified torque.
10. Reinstall the Wheel: Put the wheel back on and tighten the lug nuts.
11. Lower the Vehicle: Carefully lower the vehicle using the jack. Once on the ground, tighten the lug nuts firmly (but don't overtighten).
12. Final Tightening & Torque: Use the torque wrench to tighten the lug nuts to the manufacturer's specified torque.
13. Repeat for the Other Side: Follow the same steps for the other front wheel.
14. Pump the Brakes: Pump the brake pedal several times to restore brake pressure. You might need to press the pedal several times before it gets firm.
15. Test Drive: After making sure everything is secure, take a short test drive to check the brakes.
Important Considerations:
* Brake Pad Wear: Inspect your brake pads while the caliper is off. Replace them if they are worn below the minimum thickness.
* Torque Specifications: Always consult your owner's manual or a repair manual for the correct torque specifications for all bolts.
* ABS Sensors: Be careful not to damage the ABS sensor (if equipped) located near the hub.
Again, if you are not comfortable performing this repair yourself, it's best to have a qualified mechanic do it. Improperly installed brakes can be extremely dangerous.
