do you have to bleed drum brakes after replacing shoes

Do You Have to Bleed Drum Brakes After Replacing Shoes?

When it comes to maintaining your vehicle's braking system, it's crucial to understand the procedures that go into ensuring everything operates smoothly and safely. One common maintenance task is the replacement of brake shoes in drum brakes. However, many car owners, especially those who prefer DIY projects, have questions about whether they need to bleed the brakes after replacing drum brake shoes. In this article, we will delve into this topic to clarify when and why you might need to bleed your drum brakes.

Understanding Drum Brakes

Drum brakes consist of several components, primarily including the brake drum, brake shoes, and wheel cylinder. When you press the brake pedal, hydraulic fluid is pushed through the brake lines, causing the wheel cylinder to force the brake shoes against the inside of the drum, creating friction to slow down the vehicle.

When You Replace Brake Shoes

Replacing brake shoes can be a straightforward process, but it's essential to ensure that the system retains proper hydraulic function and safety. Typically, if you're only replacing the brake shoes and there hasn't been any leakage or issues within the brake lines or master cylinder, bleeding the brakes may not be necessary.

Situations That Require Bleeding

1. Fluid Contamination If you noticed any fluid leaks during the brake shoe replacement, it’s likely that air has entered the brake lines. In this case, bleeding the brakes is essential to remove any air bubbles which could lead to a spongy brake pedal and reduced braking effectiveness.

2. Brake Fluid Replacement If you choose to replace brake fluid during the shoe change, you will need to bleed the brakes to ensure that new fluid circulates through the system. Old fluid can accumulate moisture and debris, which can compromise braking performance. Replacing it with fresh fluid is often a good practice, but it must be followed by proper bleeding.

3. Brake System Disassembly If you had to disassemble the brake system beyond simply removing the shoes, such as removing the wheel cylinder, it is crucial to bleed the brakes. Disassembly can introduce air into the brake lines, necessitating a complete purge of air to restore full function.

How to Bleed Drum Brakes

If you determine that bleeding is necessary, here’s a simplified procedure to follow

1. Gather Your Tools You will need a brake bleeder kit, a wrench, and possibly a container to catch old brake fluid.

2. Locate the Brake Bleeder Valve Each wheel cylinder will have a bleeder screw. Start with the wheel furthest from the brake master cylinder, typically the passenger rear wheel.

3. Attach the Bleeder Kit Attach a rubber hose to the bleeder screw and place the other end in a container.

4. Open the Bleeder Valve Have an assistant pump the brake pedal several times and hold it down. Open the bleeder screw to allow fluid to escape, and observe for a stream of fluid without air bubbles. Close the screw before your assistant releases the brake pedal to avoid drawing air back into the system.

5. Repeat as Necessary Continue this process until you see clear fluid with no air bubbles at each wheel, moving from the furthest wheel to the closest.

6. Check Fluid Levels After bleeding, ensure that the brake fluid reservoir is filled to the recommended level.

Conclusion

In conclusion, whether or not to bleed your drum brakes after replacing brake shoes depends on the specific circumstances surrounding the replacement process. While it may not be necessary in all cases, certain situations—such as fluid contamination, full disassembly, or fluid replacement—can warrant a thorough bleeding. Properly bled brakes ensure safe and reliable stopping power, making this an important step in vehicle maintenance. Always remember, if you're unsure about the process, consulting a professional mechanic can provide peace of mind and assurance that your brakes are functioning safely.