Drum Brake Replacement Guide: How To Maintain And Replace Your Brakes

Drum brakes, a common type of braking system found in both older and modern vehicles, play a crucial role in slowing down or stopping a vehicle’s motion. In this article, we’ll explore how drum brakes work, the components involved, and the importance of regular inspections and drum brake replacement for optimal braking performance and safety.

Drum brake replacement

what is a drum brake

A car drum brake is a type of braking system used in some older vehicles and some modern vehicles, especially on the rear wheels. It is called a “drum” brake because it consists of a hollow drum-shaped component that rotates along with the wheel.

This drum is attached to the wheel hub, and when the brake is engaged, friction materials are pressed against the inner surface of the drum to slow down or stop the vehicle.

how do drum brakes work

Here’s how a typical car drum brake system works:

  • Drum: The drum is a circular, hollow metal component mounted on the wheel hub. It rotates along with the wheel and is an integral part of the braking system.
  • Brake Shoes: Inside the drum, there are two semi-circular brake shoes. These are curved metal plates lined with friction materials, often made of a composite material containing heat-resistant resins and abrasive components.
  • Wheel Cylinder: When you press the brake pedal, hydraulic pressure is generated in the brake lines, which is directed to the wheel cylinders located near the brake shoes. The wheel cylinders expand, forcing the brake shoes against the inner surface of the drum.
  • Friction and Braking: As the brake shoes press against the drum, the friction between the shoes and the drum creates resistance, slowing down the rotation of the drum and, consequently, the wheel attached to it.
  • Heat Dissipation: During braking, significant heat is generated due to the friction. Drum brakes are generally less effective in dissipating this heat compared to disc brakes, which may lead to reduced braking performance under heavy or repeated braking situations.

Drum brake Hardware

You need to know which part or spring your a playing with if you are planning on performing a drum brake replacement. It is no doubt that drum brakes can be intimidating yet they are very easy to understand.

So here’s a basic explanation of how it works. (Note: Drum brakes can vary from one car to another but the concept stays the same)

Drum Brake System Schematic Here: Drum Brake

The drum

The drum is a large, hollow, and cylindrical component that is attached to the wheel hub and rotates along with the wheel as the vehicle moves. It plays a critical role in the overall functioning of the braking system.

When the brake pedal is pressed, hydraulic pressure is applied to the wheel cylinder inside the brake assembly, causing the wheel cylinder to expand.

This expansion pushes the brake shoes against the inner surface of the drum, creating friction between the brake shoes’ friction material and the drum.

This friction generates heat and converts kinetic energy into heat energy, ultimately slowing down or stopping the vehicle. The drum’s main function is to provide a surface against which the brake shoes can press, generating the necessary friction for effective braking.

The shoes

Drum brake shoes are curved metal plates with friction material attached to their outer surface.

They play a crucial role in the braking process, causing friction between the brake shoes and the rotating drum. When the brake pedal is pressed, hydraulic pressure is directed to the wheel cylinder, which pushes the shoes outward.

This friction converts kinetic energy into heat energy, slowing the car’s speed.

Return Springs

Return springs are crucial mechanical components in drum brake systems, retraction of brake shoes, and brake drag prevention. They pull the shoes away from the drum’s inner surface when hydraulic pressure is released, allowing wheels to rotate freely without drag.

These springs prevent brake drag, ensure equalizing brake shoe movement, and maintain safety and performance by ensuring consistent clearance between the brake shoes and drum.

Proper functioning return springs are essential for efficient braking system operation, preventing wear, overheating, and potential brake-related issues.

Wheel cylinder

The wheel cylinder is a crucial hydraulic component in drum brake systems, converting hydraulic pressure into mechanical force to activate brake shoes and generate friction.

It functions by converting hydraulic pressure into mechanical force, pushing the brake shoes outward towards the inner surface of the rotating drum.

This friction slows the drum’s rotation, causing the vehicle to decelerate and eventually stop. When the brake pedal is pressed, the master cylinder generates hydraulic pressure, which is transmitted through brake lines to each wheel’s brake assembly. The wheel cylinder contracts, causing the piston to move back to its original position.

The wheel cylinder also ensures equalizing brake shoe movement, maintaining balanced braking performance on both sides of the wheel.

Hold down spring

Hold-down springs, also known as retaining springs or anchor springs, are mechanical components in a drum brake system.

They play a significant role in keeping the brake shoes in their proper position inside the drum assembly and preventing them from moving excessively when the brakes are released.

Auto adjuster assembly

The auto adjuster system, also known as the self-adjusting brake system (SAB), is a common feature in drum brake setups. It automatically adjusts brake shoe clearance as brake linings wear down, ensuring consistent braking performance and minimizing manual adjustments.

The system works by providing a specific clearance between brake shoes and the drum’s inner surface. As brake linings wear, the system compensates by automatically adjusting the brake shoe position during braking.

The system uses a lever mechanism to connect brake shoes to an adjuster screw or star-wheel mechanism, ensuring equal adjustment of both shoes, maintaining balanced braking performance.

parking brake

The parking brake in a drum brake system operates independently of the primary braking system. It operates using a mechanical system (cable), operated by a hand lever or foot pedal.

When the brake is engaged, a cable pulls on the mechanism, activating a lever within the drum brake assembly. The brake shoes are held in place by a bracket.

To release the parking brake, the driver disengages the hand lever or pedal, releasing tension on the cable and allowing the brake shoes to move away from the drum’s inner surface.

how to know if you need a drum brake replacement job

Knowing if your drum brakes are bad or need replacement requires paying attention to certain signs and conducting a few tests. Here are common problems to look out for, a simple drum brake test, and information on measuring drum brake thickness:

Common signs of drum brake problems

  • Scratched drums: Scratched drums are caused by worn brake lining on the brake shoes, which causes metal-to-metal contact with the drum and scratches its surface. It can cause the brake pedal to vibrate.
  • Out of round: Brake drums that aren’t perfectly round due to wear can cause brake pedal vibrations or pulsation and poor brake system performance.
  • Blue drums: A drum brake system that turns blue when overheated is less effective than standard drums. It may warp or crack.
  • Martensite spotted drums: When brake drums are overheated, they can develop small cracks on their surface. These cracks are known as martensite spots, and they can cause the brake pedal to vibrate.
  • Polished Brake lining: If the brake lining get to hot it will become glazed. This is a a big issue since the brake shoe will not be able to produce enough friction to properly function.
  • Squealing or Grinding Noise: If you hear high-pitched squealing or grinding sounds when applying the brakes, it may indicate worn-out brake shoes or other components inside the drum.
  • Pulling: If the vehicle pulls to one side during braking, there might be an issue with uneven wear or adjustment problems with the brake shoes on one side of your car.
  • Leaking Brake Fluid: Check for any signs of brake fluid leaks near the wheels, which could indicate problems with the wheel cylinders or brake lines.

How to measure drum brake thickness

Measuring the drum brake’s thickness is a great if not essential way to determine whether replacement is required or not. Furthermore, the process is very easy and doesn’t take much time.

Here’s how you can do it:

Drum

To measure a drum brake using a micrometer, begin by measuring the drum’s diameter with a measuring tape. Once you have the measurement, input it to your AMMCO style micrometer.

Then, carefully place the micrometer inside the drum and gently move it from side to side to locate the largest point on the drum’s inner surface. As you find this point, note the measurement displayed on the dial of the micrometer.

Finally, add this measured value to the original input measurement on your micrometer to obtain the accurate and precise measurement of the drum’s diameter.

This process ensures an effective assessment of the drum brake’s dimensions. You may not need to do all the following steps for a digital micrometer.

However, digital or not measure more than on spot on your drum to diagnose Out of Round. Furthermore, the drum discard specification is often written directly on the drum itself.

Shoes

To measure a shoe from a drum brake accurately, employing a precise tool like a Vernier caliper is vital to obtaining precise measurements. If the pad is riveted, start by measuring the depth of the rivet hole to determine the pad measurement.

In the case of a glued pad lining, it is essential to refer to the manufacturer’s specifications to understand whether you need to measure the lining’s thickness along with the back plate or focus solely on the lining.

Once you have this information, use the Vernier caliper to measure the appropriate sections accordingly. By following these steps and utilizing the Vernier caliper’s capabilities, you can ensure accurate measurements for the shoe from the drum brake.

minimum shoe and drum Thickness

Shoe ThicknessStandardMetric
Common Manufacturer Discard Size1/16 – 0.061.5mm
Commonly Recommended Discard Size1/10 – 0.13mm

Drum brake specifications, including thickness and size, can vary depending on the vehicle make and model. For accurate information, it’s best to refer to the vehicle’s service manual.

If you’re uncertain about inspecting or measuring drum brakes yourself, it’s always recommended to have a qualified automotive technician perform the evaluation and any necessary replacements or repairs.

Brake systems are critical to vehicle safety, and proper maintenance is crucial to ensure reliable braking performance.

how much does a drum brake replacement job cost

The cost of a drum brake replacement job can vary depending on several factors, including the make and model of the vehicle, the quality of the brake components used, the location of the repair shop, and additional services required during the replacement. However, I can provide you with a rough estimate of the potential costs involved in a drum brake replacement:

  • Brake Drum Cost: The price of the brake drum itself can range from $30 to $150 or more per drum, depending on the vehicle’s make and model and the brand of the drum.
  • Brake Shoe Cost: The brake shoe set (for both rear wheels) can cost anywhere from $20 to $100 or more, again depending on the vehicle and the brand.
  • Labor Costs: The labor cost for a drum brake replacement job can vary widely depending on the shop’s hourly rate and the complexity of the job. On average, you might expect to pay around $100 to $300 or more in labor charges.
  • Additional Parts and Services: Sometimes, other components like wheel cylinders, brake hardware, or brake fluid may need to be replaced during the brake job, which will add to the overall cost.

Taking these factors into account, a drum brake replacement job for both rear wheels might cost you approximately $200 to $700 or more in total, with parts and labor combined.

It’s worth noting that prices can vary significantly based on your location and the specific repair shop you choose.

However, if you have the necessary skills and tools, you can consider doing the drum brake replacement yourself, as it can save you on labor costs.

How to perform a drum brake replacement

Tools and equipment required

All replacement parts

  • Shoes
  • Drums
  • Springs
  • Wheel Cylinder

Shop for the best drum brake Replacement parts at advance auto parts

A video can always help to solidify written explanations. Therefore, the following video may help you to properly understand how to do a drum brake replacement: Drum Brake Replacement Video

Step 1: Jack up the car and remove the wheels

Park your vehicle on a level surface and engage the parking brake. Use the jack to lift the car at the designated jacking points. Check your vehicle’s manual for the correct locations.

Once the vehicle is lifted, place jack stands under the vehicle’s frame or axle for added safety. Slowly lower the car onto the jack stands, ensuring it is stable and secure. With the wheels off the ground, use a wrench to remove the lug nuts and take off the wheels.

Place the wheels aside for later use.

Step 2: Remove drum and clean the assembly

Pull on the drum to take it off. If it doesn’t want to come off, hit the drum with a hammer to break any rust or corrosion holding it onto the hub. Rotate the drum as you tap to ensure even force distribution. Once the drum is loose, carefully slide it off the hub.

With the drum removed, inspect the brake assembly for signs of wear, damage, or leaks. Clean the entire assembly using brake cleaner to remove dirt, dust, and debris. Don’t be shy to use a lot and be sure to place the catch pan underneath.

Step 3: Disassemble the brake shoe assembly

Pro Tip: Take a picture or make notes of the arrangement of springs, clips, and other components before disassembling the brake shoe assembly. This will help during reassembly. Furthermore, you can also position the removed parts in the same way they were on the car to give you an approximate guide.

Start by disconnecting the return springs using pliers and a screwdriver.

Depress the retaining clips and carefully remove the springs from their respective anchor points.

Detach the brake shoe hold-down springs and pins using a pair of Vice-Grips. Remove the adjuster mechanism by disconnecting the adjusting lever and spring.

As of the handbrake lever, remove it from the cable if possible. If not detach it from the shoe itself.

Step 4: Second clean

After disassembling the brake shoe assembly, clean all the parts you will be reusing utilizing brake cleaner and metal wire brush to ensure they are free of any remaining brake dust and debris.

Additionally, you want to do a second cleaning with the brake shoe assembly off to ensure full and proper cleaning. (especially brake shoe contact points)

Step 5: Replace wheel cylinder

If your inspection revealed any leaks or wear in the wheel cylinder, it’s essential to replace it. Start by disconnecting the brake line from the wheel cylinder using a line wrench to prevent damage.

Remove the mounting bolts that secure the wheel cylinder to the backing plate. Carefully remove the old wheel cylinder and replace it with a new one.

Lubricate the new wheel cylinder’s contact points with brake grease to prevent future corrosion and ensure smooth operation.

When replacing a wheel cylinder you always need to bleed the line as shown in the video above.

Step 6: reassemble Brake drum assembly

Begin reassembling the brake shoe assembly by attaching the adjuster mechanism, adjusting lever, and spring. Reinstall the brake shoe hold-down springs and pins to secure the brake shoes in place.

Reconnect the return springs to their respective anchor points using pliers. Ensure all components are correctly positioned and aligned based on the notes or pictures taken earlier.

Double-check all connections and attachments to ensure everything is in place.

Step 7: Adjust the shoes

With the brake shoe assembly reassembled, adjust the brake shoes to the proper position for a snug fit against the drum.

Use a brake adjustment tool or a flathead screwdriver to turn the adjuster mechanism until you feel slight drag. Then, back it off slightly to allow the drum to fit easily.

Step 8: Finish up and test

Carefully slide the brake drum back onto the hub, ensuring it fits snugly. Install the wheels back onto the vehicle and hand-tighten the lug nuts.

Carefully lower the vehicle from the jack stands and then use a torque wrench to tighten the lug nuts to the manufacturer’s recommended torque settings.

Test the brake pedal to ensure it feels firm, and there are no unusual noises or vibrations.

Before driving, gently pump the brake pedal a few times to ensure proper brake shoe positioning against the drum. Take the car for a short test drive at low speeds in a safe area to verify the brakes’ performance.

If everything feels and sounds normal, the drum brake replacement is complete, and your vehicle is ready to hit the road safely.

Drum brake FAQs

How long do drum brakes last

The lifespan of drum brakes can vary depending on various factors, including driving habits, road conditions, and the quality of the brake components.

Generally, drum brakes can last anywhere from 30,000 to 70,000 miles (48,000 to 112,000 kilometers) before they need replacement. However, this is just a rough estimate, and it’s essential to have them inspected regularly to ensure proper functioning.

How often should drum brakes be inspected

How often should drum brakes be inspected? Regular brake inspections are crucial for ensuring your vehicle’s safety. For drum brakes, it’s generally recommended to have them inspected at least once a year or every 12,000 to 15,000 miles (19,000 to 24,000 kilometers).

However, if you notice any signs of brake issues, such as squealing noises, reduced braking performance, or uneven braking, you should have them checked immediately, regardless of the regular inspection schedule.

Is it necessary to replace both rear drum brakes at the same time

Yes, you should replace both drum brakes on an axle simultaneously since it is essential for symmetrical wear, balanced braking performance, optimal braking efficiency, labor cost savings, safety considerations and much more. This also ensures consistent stopping power, optimal friction levels, and reduced risk of brake-related issues.

conclusion

In conclusion, a drum brake is a type of braking system commonly used in some older and modern vehicles, particularly on the rear wheels. It consists of a hollow drum-shaped component attached to the wheel hub, which rotates along with the wheel. When the brake is engaged, friction materials on the brake shoes press against the inner surface of the drum, resulting in the vehicle slowing down or coming to a stop.

The drum brake system operates through a series of components, including the drum itself, brake shoes, wheel cylinder, hold-down springs, and auto adjuster system.

To determine if a drum brake replacement is necessary, signs of wear and damage, such as scratched drums, out-of-round drums, or overheated drums, should be inspected. Measuring drum brake thickness accurately is essential to identify if replacements are needed.

Overall, maintaining the drum brake system through regular inspections and replacements is crucial for reliable braking performance and ensuring vehicle safety. By understanding the function of each component and following proper procedures, a drum brake replacement job can be effectively performed.

Disclaimer: The information provided in this text is intended for informational purposes only. Performing drum brake maintenance, inspections, or replacements improperly can be pose significant risk and lead to severe accidents, injuries, or even loss of life. It is strongly recommended to consult a certified mechanic or professional technician for any brake-related work to ensure safety and proper execution. The content is not meant to replace professional expertise and should be used at your own risk.