Here's a general outline of the process. Remember this is a *simplified overview* and might not cover all variations or potential complications:
1. Preparation:
* Safety First: Jack up the truck securely using jack stands. Never work under a vehicle supported only by a jack. Disconnect the negative battery terminal.
* Gather Tools: You'll need jack stands, a wheel chock, a socket set (metric), a torque wrench, a ball joint separator (or pickle fork – use caution!), a hammer, a press (or a sturdy vice and sockets/suitable driving surface), penetrating oil, grease, and possibly a wheel bearing race installer/remover tool. Consult your repair manual for the exact tools needed.
* Parts: Obtain the correct replacement wheel bearing assembly (often comes pre-packed with seals and races). Don't reuse old parts.
2. Removing the Wheel and Hub Assembly:
* Remove the wheel: Loosen lug nuts before jacking up the truck.
* Remove the caliper: Support the caliper with a wire or bungee cord to prevent it from dangling and damaging the brake line. Remove the caliper mounting bolts and carefully remove the caliper.
* Remove the rotor: Depending on your truck, the rotor might need to be removed next. Often it's held in place by a few bolts or can simply be pulled off after removing the caliper.
* Disconnect the ABS sensor: If equipped, carefully disconnect the ABS sensor wire from the hub assembly.
* Remove the cotter pin and castle nut: Use a socket wrench to remove the nut securing the wheel bearing to the spindle. Note the position of the cotter pin before removal to reinstall it correctly.
* Remove the hub assembly: This often requires a ball joint separator or pickle fork. Use caution to avoid damaging the ball joint. Some designs require separating the spindle from the knuckle.
3. Removing the Old Bearing:
* This is the trickiest part. You'll likely need a press to remove the old bearing from the hub assembly. Improper removal can damage the hub or bearing. A repair manual will guide you on the correct technique for your specific vehicle.
4. Installing the New Bearing:
* Install the new bearing: Use a press to carefully press the new bearing onto the hub assembly. Again, your repair manual will show the correct method to avoid damage.
* Reassemble the hub assembly: Install the hub assembly onto the spindle. Ensure it seats correctly.
5. Reassembly:
* Tighten the castle nut: Torque the castle nut to the specification stated in your repair manual. This is crucial for proper bearing operation and safety.
* Install the cotter pin: Insert the cotter pin through the castle nut and the hole in the spindle.
* Reinstall the rotor and caliper: Make sure everything is properly aligned.
* Reconnect the ABS sensor (if applicable).
* Reinstall the wheel and tighten the lug nuts: Torque the lug nuts to the specification found in your repair manual.
6. Final Steps:
* Lower the vehicle: Carefully lower the vehicle to the ground.
* Test drive: After everything is reassembled, test drive the vehicle to ensure the bearing is functioning correctly. Listen for any unusual noises.
Again, this is a simplified overview. A repair manual specific to your 2003 GMC 1500 is absolutely essential for this repair. If you're not comfortable performing this repair yourself, take your truck to a qualified mechanic. Incorrect installation can lead to serious damage or injury.
