When you apply the brakes, do you hear an odd squeaking or grinding sound from the wheels?
It might be due to a bad brake drum if you have drum brakes.
Brake drums are part of your car’s drum braking system, influencing how well your vehicle decelerates. But they can wear out over time, potentially causing dangerous situations.
This Article Contains:
- What Are Signs of a Bad Brake Drum? 6 Noticeable Symptoms
- What Are Common Brake Drum Issues?
- 5 FAQs About Brake Drums
What Are Signs of a Bad Brake Drum? 6 Noticeable Symptoms
Your vehicle can indicate drum brake problems in multiple ways.
Look out for these signs if you suspect a bad brake drum:
1. Scraping or Grinding Noise
Drum brakes comprise multiple parts that work together to slow down your car.
If the friction material or lining on the brake shoe wears out, its metal backing plate will come in contact with the brake drum. As a result, it produces a grinding or scraping noise every time you apply the brakes.
Drum brakes can also create odd sounds due to misplaced or broken brake components, such as retaining springs. Plus, brake drums that accumulate dirt, mud, and brake dust may emit strange noises too.
That’s why it’s best to have the sound diagnosed by a professional mechanic.
2. Poor Braking Performance
If your car takes too long to stop or slow down when you press the brake pedal, you may have brake drum or brake shoe issues.
However, brake system issues could also relate to a worn-out brake pad in cars that use front disc brakes and rear drum brakes. In such cases, getting your vehicle to an auto repair shop for a brake job is important, as ignoring bad brakes can lead to accidents.
PS: A standard brake job may include replacing the front disc brake pads and rear brake drum shoes, resurfacing brake rotors and drums, and bleeding the brake lines.
3. Low Brake Pedal
A low brake pedal could indicate too much space between the brake shoe and the drum.
It could also be due to a brake fluid leak or a defective master cylinder. A malfunctioning master cylinder won’t distribute hydraulic pressure properly, causing the pedal to depress right away when applying the brakes.
4. Loose Parking Brake
Worn brake drums make it difficult for brake shoes to press against the inner surface of the drum. This leads to a loose parking brake (also called the emergency brake) with lower braking efficiency.
Moreover, when the brake cable is improperly adjusted, or the drums are worn, an applied emergency brake can also cause the vehicle to slide a few inches.
5. Brake Pedal Vibrations
When brake drums become uneven or unbalanced, they can cause vibrations when you apply pressure to the brake pedal.
However, the issue may also be due to a bad disc rotor (warped rotor) or dirty brake pads.
Note: Warped rotors refers to uneven disc surfaces due to excessive heat. It’s rare for disc brake rotors to bend out of shape.
6. Soft or Spongy Brake Pedal
Cracked brake drums or air in the brake line can make your brake pedal spongy.
However, this could also be due to a leaking brake line. Since brake lines have steel tubing, they may rust and develop small holes that cause brake fluid leakage.
Why does this matter?
The reduced hydraulic pressure caused by the loss of brake fluid could make the brake pedal drop to the floor or feel spongy.
Now, let’s explore common brake drum issues that you may encounter.
What Are Common Brake Drum Issues?
Possible brake drum issues include:
- Scratched drums: Worn friction material (brake lining) on the brake shoes results in metal-to-metal contact with the drum, scratching its surface. It can cause a vibrating brake pedal.
- Out-of-round drums: Brake drums that aren’t perfectly round (due to manufacturing defects or wear) can cause brake pedal vibrations and poor brake system performance.
- Blue drums: A drum brake system that turns blue when it overheats is weaker than normal drums. It can warp or develop cracks during use.
- Martensite spotted drums: Brake drums exposed to excessive heat can develop small cracks on their surface. These cracks are called martensite spots, and they can cause a vibrating brake pedal.
- Polished drums: The brake lining can become glazed if the drum gets too hot. When this happens, the brake shoes don’t produce enough friction to slow down or stop a vehicle effectively.
Do you still have doubts about brake drums?
5 FAQs About Brake Drums
Here are some questions you may have about brake drums, and their answers:
1. What Is a Drum Brake, and How Does it Work?
A drum brake is a braking system that includes several parts, like the:
- Brake drum
- Brake wheel cylinder
- Brake shoe (that holds the brake lining)
- Backing plate
- Return spring
- Automatic adjuster
How does the system work?
When you apply the brakes, the wheel cylinder forces the brake shoes against the inner surface of the drum, creating friction that slows down or stops the wheel.
But here’s the thing:
It’s uncommon to have drum brakes on all four wheels today. Instead, some modern car models may have a rear drum brake setup (on the rear axle, aka, on each rear wheel) and a disc brake setup at the front.
2. When Should I Replace the Brake Drums?
Brake drums can last for about 200,000 miles. However, you should get a mechanic to inspect them periodically.
Worn brake drums and shoes or a faulty wheel cylinder can cause various problems with a vehicle’s braking system, potentially reducing braking performance.
The good news is that regular brake service can reduce repair costs in the long term. It’ll also help keep you safe by resolving bad brakes.
3. How Much Does Drum Brake Replacement Cost?
Here are cost estimates (including labor) for the replacement of drum brake parts:
- Brake drums: Between $330 and $500
- Drum brake shoes: Around $225 to $300
- Brake wheel cylinder: Around $160 to $195
These pricing estimates can vary based on whether you have a four-wheel drum brake setup or if they’re present only as rear brakes.
4. How Are Drum Brakes Different from Disc Brakes?
Firstly, disc brakes have different parts, like a brake pad, caliper, and brake rotor. Drum brakes have brake drums, shoes, and wheel cylinders (as mentioned above).
A disc brake setup provides good braking power and stopping ability. Moreover, the open design of a disc brake assembly allows for heat dissipation, preventing overheating.
On the other hand, drum brakes require less pressure to apply, making them easier to operate. But they need more maintenance than disc brakes since they generate more heat. However, it’s more common to have worn brake pads than worn drum brake shoes.
It’s also easier to install parking brakes in drum brakes. Plus, reconditioning the wheel cylinder is simpler than reconditioning disc brake calipers.
These factors are why some modern car manufacturers use a braking configuration of front disc brakes and rear drum brakes.
How can you tell what you have?
If your car has a rear disc brake setup, you’ll notice a rubber hose going to the brake caliper. You’ll see a metal tube if you have a rear drum brake setup.
5. Are Drum Brakes Reliable?
A drum brake system is generally reliable and provides good braking force. It’s durable and has a self-energizing effect.
However, as mentioned above, it can require more maintenance than a disc brake assembly and be prone to overheating, glazed drum brake shoes, and brake fluid vaporization.
Recognizing the key signs of bad drum brakes and addressing them early can help you retain excellent braking performance and safe driving.
Think you have a drum brake issue?
RepairSmith is a reliable auto repair and maintenance solution that offers convenient online bookings and a 12,000-mile | 12-month warranty on all repairs.
Fill out this form to get a brake service cost estimate and have one of our expert mechanics resolve your brake drum issue right from your driveway.