how do you bleed drum brakes

How to Bleed Drum Brakes A Comprehensive Guide

Bleeding drum brakes is a crucial maintenance task that ensures your vehicle’s braking system functions effectively and safely. Like any hydraulic brake system, drum brakes can develop air bubbles in the brake lines over time, which can lead to a spongy brake feel and reduced stopping power. In this article, we will discuss the step-by-step process of bleeding drum brakes and highlight the tools and precautions necessary for a successful job.

Understanding the Basics

Drum brakes operate using a different mechanism compared to disc brakes. When you press the brake pedal, hydraulic fluid is forced into the wheel cylinder, pushing the brake shoes against the inside of the drum and creating friction to stop the vehicle. If air enters this hydraulic system, it can compress under pressure, leading to ineffective braking.

Tools You Will Need

Before you start bleeding your drum brakes, gather the following tools

1. Brake fluid Ensure you have the correct type (consult your vehicle’s manual). 2. Wrench To loosen the bleed screw. 3. Clear plastic tubing This will be attached to the bleed screw and will allow you to see the fluid. 4. Catch container To collect brake fluid. 5. Helper Although you can do this alone, having someone assist you will make the process easier.

Step-by-Step Process

1. Locate the Bleed Valve Begin by identifying the brake bleed valve on the drum brake assembly. It is typically located on the rear brake wheel cylinder, near the top.

2. Prepare the Vehicle Ensure the vehicle is on a flat surface. Engage the parking brake and, if necessary, use wheel chocks to prevent movement. It is also beneficial to remove the wheel to improve accessibility.

3. Check Brake Fluid Level Before bleeding, check the master cylinder’s brake fluid level. If it’s low, top it off to prevent introducing more air into the system.

4. Attach the Tubing Place the clear plastic tubing over the bleed valve and place the other end into the catch container. This will allow you to see the brake fluid and any air bubbles that may escape.

5. Bleed the Brakes With your helper in the driver’s seat, instruct them to pump the brake pedal several times and then hold it down. While they are holding the pedal, use your wrench to loosen the bleed valve. You will notice fluid and air bubbles escaping through the tubing. Tighten the valve while your helper keeps the pedal pressed down.

6. Repeat Have your helper release the brake pedal. Check the fluid level in the master cylinder again and top it off if necessary. Repeat the pumping and bleeding process several times until you get a steady stream of clear brake fluid without air bubbles.

7. Move to Other Wheels Follow the same process for the other drum brakes. Typically, you’ll want to start with the wheel farthest from the master cylinder (usually the rear passenger side), then move to the rear driver side, front passenger side, and finish with the front driver side.

8. Final Check Once all the brakes have been bled, ensure the brake fluid level in the master cylinder is at the proper level and securely fasten the cap. Test the brakes by pressing the pedal to ensure it feels firm.

Final Thoughts

Properly bleeding your drum brakes is an essential part of brake maintenance that can significantly improve your vehicle's safety. If during the process you feel unsure or encounter problems, it is advisable to seek assistance from a professional mechanic. Regular maintenance will not only extend the life of your brakes but also ensure that you can stop safely when it matters most. Always remember to dispose of used brake fluid responsibly, as it is hazardous to the environment.