how to bleed back drum brakes

How to Bleed Back Drum Brakes A Step-by-Step Guide

Maintaining your vehicle's braking system is crucial for safety and performance. One component that may need attention is the drum brakes, particularly when air gets trapped in the brake lines during servicing or repairs. Bleeding back drum brakes is an essential process that helps ensure optimal brake function by removing air bubbles from the brake lines. This guide will walk you through the steps to successfully bleed back drum brakes.

Understanding Drum Brakes

Before delving into the bleeding process, it's essential to understand the basics of drum brakes. Unlike disc brakes, which use a caliper and rotor system, drum brakes consist of brake shoes that press against the inside surface of a spinning drum to create friction and halt the vehicle. This system is commonly found in rear brakes, and air trapped within the brake lines can lead to a spongy pedal feel and decreased braking performance.

Tools and Materials Needed

To effectively bleed back your drum brakes, you'll need the following tools and materials

1. Brake Bleeder Kit or Clear Hose A brake bleeder kit simplifies the process and often contains a one-way valve to prevent air from re-entering the lines. 2. Brake Fluid Use the manufacturer-recommended brake fluid to ensure compatibility. 3. Wrench A wrench, usually 8mm or 10mm, is necessary to open the bleeder valve. 4. Container A small container to catch the old brake fluid. 5. Rag or Towels To clean up any spills.

Step-by-Step Bleeding Process

Step 1 Prepare the Vehicle

Ensure the vehicle is parked on a level surface with the engine off. Engage the parking brake for extra safety, and if necessary, remove the wheels to gain access to the drum brakes.

Step 2 Locate the Bleeder Valve

The bleeder valve is typically located on the brake cylinder near the top of the brake assembly. Identify the driver's side and passenger's side valves.

Step 3 Fill the Master Cylinder

Open the hood and locate the brake fluid reservoir (master cylinder). Remove the cap and check the fluid level. Top it off with new brake fluid to prevent air from entering the system during the bleeding process.

If using a brake bleeder kit, attach it to the bleeding valve. If using a clear hose, insert one end onto the valve and place the other end into the container.

Step 5 Open the Bleeder Valve

Using the wrench, carefully turn the bleeder valve counterclockwise to open it. Be ready to catch the fluid as it starts to flow out. Make sure someone is in the driver’s seat to assist with the next step.

Step 6 Pump the Brake Pedal

Have an assistant pump the brake pedal several times until they feel resistance, then hold the pedal down. This action helps to push fluid and any trapped air out of the system.

Step 7 Close the Bleeder Valve

While the pedal is held down, close the bleeder valve securely to prevent air from being sucked back into the brake line. Instruct your assistant to release the brake pedal slowly.

Step 8 Repeat the Process

Repeat the pumping and bleeding process until you see a steady stream of clear brake fluid without bubbles emerging from the bleeder hose. It’s typically a good idea to start bleeding from the wheel farthest from the master cylinder (usually the passenger rear) and work your way to the closest (driver front).

Step 9 Top Off Brake Fluid

Throughout the process, continually check the master cylinder’s fluid level and top it off as necessary, as low fluid levels can introduce air back into the system.

Step 10 Test the Brakes

Once all wheels have been bled, recheck the fluid level, and replace the cap on the master cylinder. Spin the wheels and press the brake pedal to ensure it feels firm and responsive. Take the vehicle for a slow test drive in a safe area to confirm that the brakes are functioning properly.

Conclusion

Bleeding back drum brakes can seem challenging, but with the proper tools and a clear understanding of the steps involved, you can ensure your brakes perform at their best. Regular maintenance of your braking system not only enhances safety but also improves overall vehicle performance. Always remember, if you feel uncertain at any step, consulting a professional mechanic is the safest choice.