If you have drum brakes (most likely):
This is a more involved job than disc brakes, and it's strongly recommended you have the proper tools and some mechanical aptitude. If you're uncomfortable with this, take it to a mechanic.
Tools you'll likely need:
* Jack and jack stands: Crucial for safety. Never work under a vehicle supported only by a jack.
* Lug wrench: To remove the wheels.
* Wheel chocks: To prevent the truck from rolling.
* Hammer: For various tasks.
* Socket wrench set: Various sizes, including those for lug nuts.
* C-clamp (or similar): To compress the brake cylinder. This is essential to allow you to get the new shoes in.
* Screw driver (flathead and Phillips): Possibly needed to remove parts.
* Brake grease: To lubricate parts.
* New brake shoes: Make sure to get the correct ones for your specific truck.
* Wire brush: To clean up rusty parts.
* Safety Glasses and Gloves: Protect your eyes and hands.
Steps (Drum Brakes):
1. Safety First: Park on a level surface, engage the parking brake, and chock the front wheels. Jack up the rear of the truck and securely place it on jack stands.
2. Remove the Wheel: Remove the lug nuts and take off the wheel.
3. Remove the Drum: Sometimes the drum will just pull off. Other times it might be stuck due to rust. If it's stuck, gently tap around the edge with a hammer while working it back and forth. Do *not* use excessive force, as you can damage the drum.
4. Inspect the components: Carefully inspect the brake shoes, wheel cylinder, and other components for wear and tear. Replace any parts showing significant wear or damage.
5. Compress the Wheel Cylinder: Use the C-clamp to compress the wheel cylinder. This retracts the wheel cylinders and allows you to install the new shoes.
6. Remove the Old Brake Shoes: The old shoes should now be relatively easy to remove. Take note of how they are installed, as the new ones should go in the same way.
7. Install the New Brake Shoes: Install the new brake shoes, ensuring they are properly seated.
8. Reassemble: Reinstall the drum. If it’s difficult to put back on, gently tap it around the edges with a hammer.
9. Adjust the Brake Shoes: Most drum brakes have an automatic adjuster, but it's still good to check that the brake pedal feels firm after reassembly. If you need to adjust the shoes, there will be adjustment mechanisms inside the drum. Consult your repair manual for specifics.
10. Reinstall the Wheel: Replace the wheel and tighten the lug nuts. Lower the truck from the jack stands.
11. Test the Brakes: Test your brakes *carefully* and ensure they are working properly before driving.
If you have disc brakes: The process is different. You'll need to remove the caliper, and likely use a caliper piston compression tool to retract the caliper piston before installing the new pads. This is generally easier than drum brakes.
Important Note: This is a simplified guide. A detailed repair manual specific to your 1999 GMC Sierra 1500 is highly recommended for a comprehensive understanding of the procedure. Improper brake maintenance can be dangerous. If you are not comfortable performing this repair yourself, take your vehicle to a qualified mechanic.
