Drum Brake Replacement: Is It Tricky?

When it comes to the braking systems on vehicles, most modern cars have transitioned to disc brakes, particularly on the front wheels. However, drum brakes are still prevalent on many rear axles, especially in older models or certain types of vehicles like trucks and some smaller cars. While they might seem less common, understanding how they work and how to maintain them is crucial for any budding mechanic or car owner looking to save money on repairs. A common question that arises is: Are drum brakes hard to change? The answer, like many things in automotive maintenance, is nuanced. It depends on several factors, including your mechanical aptitude, the condition of the existing brakes, and whether you've taken the time to familiarise yourself with the system.

Understanding Drum Brakes

Before diving into the replacement process, it's essential to grasp the fundamental components of a drum brake system. Unlike disc brakes, which use a caliper to squeeze a pad against a rotor, drum brakes operate internally within a drum. The main components include:

• Brake Drum: A cylindrical metal component that rotates with the wheel. The inside surface of the drum is where the brake shoes make contact.
• Brake Shoes: Curved metal pieces lined with a high-friction material (the brake lining). When you apply the brakes, these shoes are forced outwards against the inner surface of the drum.
• Wheel Cylinder: A hydraulic cylinder with pistons at each end. When brake fluid pressure is applied, these pistons extend outwards, pushing the brake shoes.
• Return Springs: These springs pull the brake shoes back to their resting position when the brake pedal is released. There are typically upper and lower return springs.
• Retracting Springs: These springs also help retract the shoes.
• Parking Brake Strut/Lever: Mechanisms that engage the parking brake, often working in conjunction with the main brake shoes.
• Adjuster: A mechanism that compensates for the wear of the brake linings, ensuring proper contact between the shoes and the drum over time.

When Drum Brakes Can Be More Difficult

The primary factor that increases the difficulty of changing drum brakes is their condition. If the components are significantly worn, corroded, or seized, the process can become considerably more challenging.

Worn Components:

When brake shoes are heavily worn, the pistons in the wheel cylinder have to extend further to make contact with the drum. This can make it more difficult to compress the pistons back into the cylinder when installing new, thicker shoes. The return springs might also be weakened and less effective, making it harder to pull the old shoes away.

Corrosion and Seizure:

Rust and dirt are the enemies of any brake system. If the drum has been exposed to moisture and road salt for extended periods, it can corrode. This corrosion can cause the drum to seize onto the hub or the brake shoes to become stuck to the inside of the drum. In such cases, considerable force, penetrating oil, and potentially even specialized tools may be required to separate the drum.

Broken Springs or Hardware:

The intricate system of springs and clips that hold the brake shoes in place can become brittle or break over time, especially with heat cycles. If a spring snaps inside, it can make removal difficult and it's crucial to replace all the associated hardware with new parts to ensure proper function and safety.

Preparation is Key: Learning with New Brakes

A highly recommended strategy for anyone unfamiliar with drum brakes is to disassemble a set of new drum brakes. This might sound counterintuitive, but it's an excellent way to understand the layout and how all the springs and components connect. By carefully taking apart a new set, you can visually note the location of each spring and clip. This mental picture will be invaluable if you encounter worn brakes later, where the original placement of these small but vital parts might not be immediately obvious. It's like building a jigsaw puzzle with the instructions – much easier than trying to figure it out from scratch when the pieces are old and potentially bent.

Step-by-Step Guide to Changing Drum Brakes (General Overview)

While the exact procedure can vary slightly between vehicle makes and models, here's a general outline of the process:

1. Safety First!

Ensure the vehicle is on a level surface, the parking brake is off (unless you're working on the rear and need it to hold), and the wheels are chocked. Use sturdy jack stands to support the vehicle securely before removing the wheel. Never rely solely on a jack.

2. Remove the Drum

This is often the first hurdle. If the drum is not seized, it might slide off after removing any retaining clips or nuts. If it's stubborn, you might need to use a rubber mallet to tap it free. For severely seized drums, a specialized drum puller tool might be necessary.

3. Document the Layout

Take clear photos or sketch the arrangement of the springs, shoes, and hardware. This is where your preparation with new brakes will pay dividends.

4. Remove Old Components

Carefully detach the return springs, retracting springs, and any clips holding the shoes in place. You may need brake spring pliers for this. Once the springs are off, the brake shoes should be free to remove. Be mindful of the wheel cylinder pistons, which can pop out if not supported.

5. Clean and Inspect

Clean the inside of the drum (if reusing) and the backing plate. Inspect the wheel cylinder for leaks, the parking brake mechanism, and the adjuster. If the drum is worn beyond its service limit or heavily scored, it should be replaced or resurfaced by a professional.

6. Install New Components

Reverse the disassembly process. Install the new brake shoes, ensuring they are correctly oriented. Reconnect the return springs and retracting springs, using spring pliers. Ensure all clips and pins are in place. It can be helpful to pre-stretch the springs slightly before attaching them.

7. Reinstall the Drum

Slide the drum back onto the hub. You may need to slightly retract the brake shoes using the adjuster to get the drum to fit over the new linings.

8. Adjust the Brakes

Most drum brake systems require manual adjustment. This is typically done by rotating the adjuster star wheel until the brake shoes are close to the drum, then backing off a few clicks to allow the drum to spin freely with minimal drag. Consult your vehicle's service manual for the specific adjustment procedure.

9. Reinstall Wheel and Test

Put the wheel back on, tighten the lug nuts, and lower the vehicle. Pump the brake pedal several times until it feels firm. This is crucial to seat the pistons in the wheel cylinder and expand the shoes. Test the brakes gently at low speed in a safe area before driving normally.

Common Pitfalls and Tips

• Spring Tension: The springs can be under significant tension. Be careful when removing and installing them to avoid injury or launching them across the garage.
• Correct Shoe Placement: Ensure the shoes are installed in the correct orientation. There's usually a leading and trailing shoe, which might have different lining thicknesses.
• Hardware Kits: Always use a new hardware kit that includes springs, clips, and pins. Reusing old hardware is a common cause of brake failure or poor performance.
• Wheel Cylinder Leaks: If you notice brake fluid leaking from the wheel cylinder, it must be replaced.
• Drum Condition: Check the inside diameter of the drum against the maximum specified limit in your service manual. Over-sized drums can lead to reduced braking effectiveness.

Frequently Asked Questions

Q1: How long does it take to change drum brakes?

For an experienced mechanic, it can take anywhere from 30 minutes to an hour per side. For a DIYer, especially on their first attempt, it could take 1-3 hours per side, depending on the complexity and any seized components.

Q2: Do I need special tools to change drum brakes?

While some tasks can be done with standard tools, specialized tools like brake spring pliers, a brake shoe retainer clip tool, and potentially a drum puller can make the job significantly easier and safer.

Q3: Can I just replace the brake shoes?

It's highly recommended to replace all the associated hardware, including springs and clips, at the same time. If the drum is worn or scored, it should also be replaced or resurfaced. Ignoring these can lead to premature wear of the new shoes or compromised braking performance.

Q4: What does it mean if my drum brakes are noisy?

Noises like squealing, grinding, or clicking can indicate worn brake shoes, loose components, or foreign debris in the drum. It's a sign that an inspection and likely replacement are due.

Q5: Is it safe to drive with worn drum brakes?

No. Worn drum brakes significantly reduce your vehicle's stopping power, compromising safety for yourself and others. They should be replaced as soon as possible.

Conclusion

So, are drum brakes hard to change? If the components are in good condition and you've prepared by understanding the system, it's a manageable DIY task. However, if you're faced with heavily worn, corroded, or seized parts, the difficulty can escalate significantly, requiring more time, patience, and potentially specialized tools. The key takeaway is preparation and understanding. Familiarising yourself with the system, using a hardware kit, and being methodical will greatly increase your chances of a successful and safe brake job.