1. Safety Precautions: Engage the parking brake, chock the rear wheels, and properly lift and support the car with a jack or car ramps to ensure it's stable during the repair process.
2. Remove the Wheel: Use a lug wrench to loosen and remove the bolts holding the wheel in place. Then, carefully remove the wheel.
3. Disconnect the Brake Caliper: Remove the bolts securing the brake caliper to the steering knuckle. Be cautious not to damage the brake line. Use a piece of wire or string to hang the caliper out of the way without straining the brake line.
4. Remove the Brake Rotor: In most cases, the brake rotor is attached to the wheel hub. Use a wrench or socket to remove the bolts holding the rotor in place, and carefully remove the rotor.
5. Remove the Steering Knuckle: Remove the bolts securing the steering knuckle to the control arm and any other components that may hold it in place. Carefully remove the steering knuckle assembly, taking care not to lose any small parts such as washers or shims.
6. Remove the Old Bearing: Use a specialized bearing removal tool or a slide hammer to extract the old bearing from the steering knuckle. Be careful not to damage the surrounding components.
7. Install the New Bearing: Press the new bearing into the steering knuckle using the appropriate tool or by tapping it in evenly with a mallet and a suitable drift punch. Ensure the bearing is seated correctly and flush with the surface.
8. Reassemble the Steering Knuckle: Reinstall the steering knuckle onto the control arm and reconnect any previously removed components. Tighten the bolts securely.
9. Reconnect the Brake Caliper: Reinstall the brake caliper and reconnect it to the steering knuckle using the bolts removed earlier. Make sure the brake caliper is securely attached.
10. Install the Brake Rotor: Place the brake rotor back onto the wheel hub and secure it with the bolts you removed earlier.
11. Install the Wheel: Reinstall the wheel onto the hub and tighten the lug bolts. Lower the vehicle carefully if it was raised with a jack or ramps.
12. Test the Brakes: Perform a test drive to ensure the brakes are functioning correctly and that there are no unusual noises or vibrations.
13. Final Check: Double-check all bolts and connections to ensure everything is secure.
It's important to note that the above steps are a general guideline and may vary depending on the specific model and year of your Astra. Always refer to the vehicle's repair manual for accurate and detailed instructions. If you're not comfortable performing this repair, it's advisable to seek assistance from a qualified mechanic.
