Post-Winter Vehicle Safety: Drum Brake Maintenance

Spring is a season of new beginnings, making it the perfect time to give your vehicle’s brake system a fresh start. Just like spring cleaning clears out the clutter, a thorough brake inspection helps address the wear and tear left behind by winter.

Cold temperatures, road salt, moisture, and debris all take a toll on brake components, especially in heavy-duty and commercial vehicles. Conducting a full post-winter brake inspection can improve safety, enhance performance, and reduce the risk of unexpected downtime in the busy months ahead.

Check out this guide and let’s walk through key drum brake components to inspect and maintain, including brake shoes, slack adjusters, S-cams, brake hardware, and brake drums.

Brake Shoes: Springtime Inspection

Brake shoes are critical to overall brake performance and safety. After the cold season, they deserve close attention.

Inspection Tips:

• Uneven or excessive wear? Harsh winter braking can lead to irregular wear patterns that affect performance.

• Signs of contamination? Road salt, moisture, and grease can compromise the friction material on the brake shoes, reducing braking efficiency.

• Signs of rust-jacking? Corrosion between the brake shoe and friction leads to cracked and broken linings, diminishing brake performance to unsafe levels.

• What is the lining thickness? Brake shoes (by axle) that are worn near or beyond the manufacturer’s minimum thickness guides will invite a DOT out-of-service violation.

Maintenance Best Practices:

• Clean away any debris or residue from both the shoes and drums to ensure proper function.

• Confirm the shoes move freely within their guides and are not binding or sticking.

• Replace brake shoes by the axle and use high-quality, OEM-approved replacements such as Meritor Genuine and Meritor brake shoe kits.

Meritor’s brake shoes are engineered for long life and consistent braking under demanding conditions. Explore replacement options on MeritorPartsXpress.com.

Slack Adjusters: Keep Brake Adjustment on Point

Slack adjusters maintain proper brake shoe-to-drum clearance, and their performance has a direct impact on braking effectiveness and safety. Poorly adjusted brakes can have diminished stopping power or drag.

Inspection Checklist:

• Verify that automatic slack adjusters are functioning correctly and adjusting as they should per the OE guidelines.

• Use a brake stroke gauge to manually check the brake stroke and ensure it is within specification.

• Look for corrosion, loose connections, or damaged components that may interfere with the operation of the brakes.

When to Replace:

• Brake stroke exceeds allowable limits. In many countries, safety regulations set maximum allowable brake stroke lengths. If the push rod travel exceeds these limits, it indicates that the brake system is not applying sufficient force to stop the vehicle safely.

• Adjustment is inconsistent or fails completely, even after proper lubrication. This is a sign that the slack adjuster may no longer be functioning as intended and should be replaced.

Meritor offers a wide range of high-performance slack adjusters, designed for dependable service life and operation.

S-Cams: Small Part, Big Impact

S-cams play a crucial role in the braking system by directly activating the brake shoes. Coming out of winter, exposure to moisture, salt, and debris can lead to buildup and wear that affects their operation.

Inspection Tips:

• Check for flat spots, cracks, or abnormal wear on the cam head that could indicate uneven contact or excessive friction.

• Rotate the cam by hand to ensure it moves freely and smoothly. Check the axial and radial movement of the s-cam with a gauge.

• Inspect bushings, seals, and support brackets for signs of wear, looseness, or damage. Replace all these components when replacing a s-cam.

Maintenance Tips:

• Grease S-cam bushings as part of regular service intervals.

• Replace worn or corroded S-cams before they lead to issues like uneven braking,brake shoe drag, or damage to other components.

Explore durable S-cam solutions through Meritor’s aftermarket catalog to restore safe braking performance.

Brake Hardware: Don’t Overlook the Small Stuff

Hardware components like return springs, pins, rollers, and anchor brackets might be small, but they are essential for proper brake function.

Common Post-Winter Issues:

• Rusted or fatigued springs can cause brakes to drag or fail to return properly.

• Worn pins and rollers may result in inconsistent braking pressure or uneven shoe wear.

Best Practices:

• Check all brake hardware during every brake inspection.

• Always replace the brake hardware as a set when installing new brake shoes. This helps ensure balanced operation, even pad wear, and longer component life.

With Meritor brake shoe kits, you receive brake shoes, hardware, and everything you need to streamline service and extend uptime.

Brake Drums: Spring Maintenance Musts

Here are the inspection steps to follow when it comes to brake drums – a critical part of the drum brake system.

Inspection Steps:

• Measure drum wear using a reliable tool like Meritor’s drum gauge to check for bell mouthing, out-of-round conditions, and overall wear.

• Confirm the internal diameter does not exceed specifications—for a 16.5-inch drum, the maximum is 16.620 inches (0.120 inches total wear).

• Visually inspect for heat checking—fine cracks that appear closed at rest but expand with brake applications.

• Check for signs of scoring or hot spotting; if present, replace the drum.

• Ensure no section of the drum is missing or broken.