Brake Shoes: Function, How to Measure, and FAQs

Written by

CarParts.com Research Team

Automotive and Tech Writers

Updated on October 24th, 2024

Reading Time: 5 minutes
Summary
  • Brake shoes are crescent-shaped components inside the brake drum that slow the wheel down when you step on the brake pedals.
  • Some symptoms of a bad brake shoe include squealing noises, difficulty in braking, vibrations when braking, a loose brake pedal, and an illuminated brake light warning sign.
  • Brake shoes tend to last up to 80,000 miles or more.

There are two types of braking systems, one of them being drum brakes. This system has four major components that all work together to stop your vehicle. One of the most crucial parts of the system is the brake shoes. If damaged, it could result in brake failure.

What Are Brake Shoes?

Brake shoes are crescent-shaped components located inside the brake drum. They have a rough friction material on one side, so when you press the brake pedal, the shoes are forced outward and against the brake drum to slow the wheel down.

Drum brakes are a type of braking system with a brake lining that generates a stopping force once pressed against the drum. It has a counterpart called the disc brake system. Drum brakes have brake shoes, while disc brake systems have brake pads.

Brake Shoes vs. Brake Pads

While brake shoes and brake pads are both braking system components, they’re typically used in different types of brakes.

Brake Pads

Brake pads are used in disc brakes, commonly found on the front wheels of modern cars.

Stepping on the brake pedal causes hydraulic pressure to force the brake caliper to squeeze the brake pads against the rotor, creating the friction needed to slow and stop the vehicle.

Brake Shoes

Brake shoes are used in drum brakes, which are less common on modern vehicles.

Compared to disc brakes, drum brakes use hydraulic pressure to push outward against the brake shoes, which press against the inner surface of the brake drum to create stopping friction.

How to Measure Brake Shoes

Getting the brake shoes’ measurement is crucial because once they wear, metal-to-metal contact occurs and can damage the drum. Measuring the shoe lets you check if it’s running thin and prevents damage to the drum.

To measure the brake shoes, you’ll need the following tools and equipment:

  • Brake Shoe Gauge
  • Vernier Caliper
  • Depth Gauge
  • Shop Ruler
  • Flashlight
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Once you have these tools, follow the steps below:

Prepare the Brake Shoe

Remove the brake shoes (see steps below) and check for damage or wear. Use a brake cleaner or compressed air to remove any debris or contaminants.

Measure the Lining Thickness

Place the brake shoe gauge against the lining material, ensuring it’s perpendicular to the surface. Read the measurement from the scale on the gauge. Repeat these steps for each shoe.

Measure the Width

Use the vernier caliper to measure the width by placing it against the shoe’s outer edges until it fits. Read the measurement from the scale and repeat for each shoe.

Measure the Length

Follow the same steps above, but this time, measure the length of each shoe.

Check for Groove Depth

Use the depth gauge to measure the depth of any grooves or indentations on the brake shoe lining by placing the gauge inside the groove. Read the measurement from the gauge and record it.

Check the Brake Shoes

Look at the condition of the brake shoes again to see if there are issues you need to address.

Symptoms of a Bad Brake Shoe

Some symptoms of a bad brake shoe include squealing noises, difficulty braking, vibrations when braking, a loose brake pedal, and an illuminated brake light warning sign.

Squealing Noises

When you start braking and hear a squealing noise, it might be due to a worn brake shoe scraping against the inside part of the drum brake. To prevent this, you can use brake cleaners to avoid dust buildup.

Difficulty Braking

The brake shoes are responsible for stopping the vehicle, so once they are worn, it’ll get more difficult to brake. You might also notice a significant reduction in stopping power.

Vibrations When Braking

Vibrations when using the brake pedal could indicate the brake shoes are starting to wear. Once this happens, the entire drum brake will shake, and the vibrations will travel to the pedal.

Loose Brake Pedal

Another indication of a worn brake is a spongy or soft brake pedal. This occurs because drum brakes have a self-adjuster to maintain the appropriate distance between them and the brake shoes. Once the shoes are worn, the distance increases, resulting in a spongy feeling.

Illuminated Brake Light Warning Sign

An illuminated brake light warning indicates an issue with the braking system, meaning there are different possible reasons why it’s lit. One of them is a worn brake shoe because it affects performance.

Once you notice the warning light is on, it’s best to have a mechanic look at the braking system to diagnose the reason instead of trying to replace the shoe immediately. Doing so ensures you don’t waste time and money fixing a component that might have been working properly.

How to Change Brake Shoes

Changing the brake shoes can be broken down into three steps: removing the brake drums, removing the brake shoes, and changing them.

Changing the brake shoes can be broken down into three steps: removing the brake drums, removing the brake shoes, and changing them. To do all three, you’ll need the following tools and equipment:

  • Jack stand
  • Tire iron
  • Screwdriver
  • Ratchet
  • Rust remover (optional)
  • Pliers

Brake Drum Removal

You’ll first have to remove the brake drums to access and remove the brake shoes. To do so, follow the steps below:

  • Step 1: Park the vehicle and jack it up to remove the wheels. Use a tire iron to loosen the lug nuts on the wheels.
  • Step 2: Remove the dust cap with a screwdriver by sliding it beneath the cap’s gap and pry it toward you.
  • Step 3: Use a ratchet to unscrew the axle-bearing nut located beneath the dust cover.
  • Step 4: Twist the drum while pulling backward to remove it.

Brake Shoe Removal

To remove the brake shoes, follow the steps below:

  • Step 1: Use pliers to remove the brake shoe springs located beneath the drum. Some vehicles have one, others two.
  • Step 2: Pull out the two brake shoe clips using pliers.
  • Step 3: Remove the parking brake cable. Your car’s service manual should provide better guidance as to how.
  • Step 4: Pull the brake shoe from the backing plate by pulling it toward you.

Brake Shoe Replacement

Lastly, changing the brake shoe requires you to do the following steps:

  • Step 1: Check if the old and new brake shoes are identical to ensure fit.
  • Step 2: Starting with the springs, remove the components on the brake shoe set you pulled and place them on the new brake pads.
  • Step 3: Reset the parking brake adjuster by pushing the adjuster wheel away from the pin as you install it onto the new brakes.
  • Step 4: Use pliers to pull the parking brake spring away from the end of the cable to make it easier to install onto the brake assembly.
  • Step 5: Press the shoe set against the backing plate before reinstalling the brake shoe clips previously removed.
  • Step 6: Reconnect the brake springs by using a plier.
  • Step 7: Install the new drum (if you have one) by placing it over the brake shoe set and screwing the axle nut to hold it in place.

How Long Do Brake Shoes Last?

The lifespan of brake shoes depends on where and how you drive the vehicle. Generally, they can last up to 80,000 miles or more, but that could be cut down to 30,000 to 35,000 if you’re driving somewhere urban.

Written By CarParts.com Research Team

Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.