How To Adjust Drum Brakes

How to Adjust Drum Brakes: A Comprehensive Guide for DIY Mechanics

Drum brakes, while less common in modern vehicles than disc brakes, are still found on many cars, trucks, and motorcycles. Understanding how to adjust drum brakes is a valuable skill for any DIY mechanic, allowing you to maintain your vehicle's braking system and ensure safe and efficient stopping power. This comprehensive guide will walk you through the process step-by-step, covering everything from identifying the components to troubleshooting common issues. We'll cover both manual and self-adjusting drum brakes, equipping you with the knowledge to tackle this essential maintenance task.

Introduction: Understanding Drum Brake Mechanics

Before diving into the adjustment process, it's crucial to understand how drum brakes function. Unlike disc brakes which use calipers to squeeze pads against a rotating disc, drum brakes utilize a system of shoes and cylinders within a rotating drum. The brake shoes, lined with friction material, are pushed outwards against the inside of the drum when the brake pedal is depressed. This friction converts kinetic energy into heat, slowing and stopping the vehicle. The effectiveness of this braking depends on the proper clearance between the shoes and the drum. If the clearance is too large, the brakes will feel spongy and ineffective. If it's too tight, the brakes will drag, causing overheating and reduced fuel efficiency. Therefore, proper adjustment is paramount.

The adjustment mechanism varies depending on the type of drum brake system:

• Manual Adjustment: These systems require periodic manual adjustment using a star wheel or similar mechanism located within the brake drum. They are simpler in design but require more regular maintenance.
• Self-Adjusting: These systems incorporate an automatic mechanism that adjusts the brake shoes as they wear down. While requiring less frequent manual intervention, they can still malfunction and require attention.

Tools and Materials You'll Need

Before you begin, gather the necessary tools and materials. This will save you time and frustration during the process. You'll likely need:

• Jack and jack stands: To safely lift and support your vehicle.
• Wheel chocks: To prevent the vehicle from rolling.
• Lug wrench: To remove the wheel.
• Socket wrench set: To access and adjust brake components.
• Screwdrivers (Phillips and flathead): For various tasks, depending on your vehicle's design.
• Pliers: For gripping and manipulating small parts.
• Brake cleaner: To remove grease and grime from brake components.
• Wire brush: To clean brake drum surfaces.
• Owner's manual: Consult this for vehicle-specific instructions and torque specifications.
• Gloves and safety glasses: To protect yourself from grease and debris.
• Torque wrench: Essential for tightening bolts to the manufacturer's specified torque.

Step-by-Step Guide to Adjusting Manual Drum Brakes

This process outlines the adjustment of manual drum brakes. Always consult your vehicle's owner's manual for specific instructions and diagrams relevant to your make and model.

1. Preparation:

• Park on a level surface: Ensure the vehicle is securely parked on a level, stable surface. Engage the parking brake.
• Lift and support the vehicle: Use a jack and jack stands to lift the vehicle and securely support the wheel you'll be working on.
• Remove the wheel: Use the lug wrench to remove the wheel nuts and take off the wheel.

2. Accessing the Drum and Adjustment Mechanism:

• Remove the brake drum: Depending on your vehicle, you may need to carefully tap the drum with a rubber mallet or use a drum puller to remove it. Sometimes, residual brake dust and rust can cause it to stick. If you have difficulty removing the drum, be patient and avoid forceful pounding.
• Locate the adjusting mechanism: The mechanism will typically be a star wheel or a similar device located between the brake shoes. This is often accessed through a hole in the backing plate.

3. Adjusting the Brakes:

• Clean the brake components: Thoroughly clean the brake drum, shoes, and adjustment mechanism using brake cleaner. A wire brush can be useful for removing stubborn rust or debris. Pay close attention to the star wheel itself, making sure it's clean and operates freely.
• Adjust the star wheel: Carefully turn the star wheel using a suitable tool (often a screwdriver or special adjustment tool). Turning the wheel clockwise will tighten the brakes (push the shoes outward), while counter-clockwise will loosen them.
• Check for proper clearance: After each adjustment, rotate the drum by hand. You should feel a slight resistance as the shoes make contact with the drum. There should be enough clearance to rotate the drum freely but with noticeable friction. The exact amount of clearance will vary depending on the vehicle, but the goal is to find the point where the brakes are just beginning to engage without dragging.

4. Reassembly:

• Reinstall the brake drum: Carefully place the brake drum back onto the axle. It should slide on easily; if it doesn't, double-check your adjustments.
• Reinstall the wheel: Replace the wheel and tighten the lug nuts to the manufacturer's specified torque using a torque wrench.
• Lower the vehicle: Carefully lower the vehicle from the jack stands.

5. Testing the Brakes:

• Test the brakes: After adjusting the brakes, always test them thoroughly in a safe, controlled environment. Ensure that the brakes are firm and effective without any dragging. If the brakes feel spongy or ineffective, you may need to repeat the adjustment process.

Adjusting Self-Adjusting Drum Brakes

Self-adjusting drum brakes use a mechanism that automatically adjusts the shoes as they wear. However, these systems can malfunction and may require manual intervention. The process of adjusting self-adjusting brakes often involves engaging the parking brake multiple times to allow the self-adjusting mechanism to function. This is usually done in conjunction with reversing the vehicle back and forth while applying the brakes. However, the specifics depend entirely on the vehicle model, and it's advisable to consult your owner's manual for the correct procedure. If you notice uneven wear on your brake shoes or the self-adjusting mechanism is clearly not working, it's best to seek professional assistance from a qualified mechanic.

Understanding Brake Shoe Wear and Replacement

During the adjustment process, it's important to visually inspect the brake shoes. If the shoes are worn excessively (the friction material is thin or worn down to the rivets), they will need to be replaced. Brake shoes with insufficient friction material will not provide adequate stopping power and are a significant safety hazard. Uneven wear on the brake shoes can indicate other problems within the braking system, such as a sticking caliper or a problem with the wheel cylinder. If you notice uneven wear, it's crucial to have a qualified mechanic diagnose and address the underlying issue.

Troubleshooting Common Drum Brake Issues

During the adjustment process or after completing it, you might encounter some problems. Here are some common issues and their solutions:

• Brake drag: This occurs when the brakes are slightly engaged even when the pedal is not pressed. This is typically due to the brakes being adjusted too tightly. Loosen the star wheel slightly to remedy the problem.
• Spongy brakes: This indicates insufficient brake pressure. This could be due to low brake fluid, air in the brake lines, a leak, or the brakes not being adjusted properly. Check the brake fluid level and bleed the brakes if necessary.
• Ineffective braking: If the brakes are not stopping the vehicle effectively, it could indicate worn-out brake shoes, a problem with the wheel cylinder, or inadequate adjustment. Inspect the brake shoes for wear and adjust the brakes accordingly. If the problem persists, seek professional help.
• Difficulty removing the brake drum: If you struggle to remove the brake drum, it may be stuck due to rust or debris. Use a brake drum puller if necessary. Do not use excessive force, as you could damage the drum or other components.

Frequently Asked Questions (FAQs)

Q: How often should I adjust my drum brakes?

A: The frequency depends on several factors, including driving habits and the type of brake system (manual or self-adjusting). For manual systems, regular inspection and adjustment are necessary. For self-adjusting systems, less frequent manual intervention is usually required, but regular inspection is still vital. Consult your owner’s manual for specific recommendations.

Q: Can I adjust my drum brakes without removing the wheel?

A: No, you cannot adjust drum brakes effectively without removing the wheel. The process requires access to the brake drum and adjustment mechanism, which are located behind the wheel.

Q: What happens if I over-adjust my drum brakes?

A: Over-adjusting can lead to brake drag, overheating, and reduced fuel efficiency. In severe cases, it can also damage the brake components.

Q: Can I use a power drill to adjust the star wheel?

A: While tempting, using a power drill is not recommended. The star wheel is delicate and can be easily damaged. Manual adjustment provides better control and reduces the risk of damage.

Q: What if I can't find the star wheel?

A: If you can't locate the star wheel, consult your owner's manual or seek help from a qualified mechanic. The location and design of the adjustment mechanism vary significantly depending on the make and model of your vehicle.

Conclusion: Ensuring Safe and Reliable Braking

Adjusting drum brakes is an important maintenance task that ensures safe and effective braking. While this guide provides a comprehensive overview, remember that the specific procedures may vary depending on your vehicle's make and model. Always consult your owner's manual for vehicle-specific instructions and torque specifications. If you're uncomfortable performing this task yourself, don't hesitate to seek professional assistance from a qualified mechanic. Prioritizing brake safety is crucial for the well-being of yourself and others on the road. Regular maintenance, including proper adjustment and inspection, contributes significantly to a safe and reliable braking system. Remember that a well-maintained braking system is a crucial element of safe driving.