Know When You Need To Replace Your Brake Drums – 7 Common Brake Drum Issues & How To Correct Them

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Find out what is causing your brake drum issue and how you can correct the problem without breaking the bank.

The performance you get from your brake system can literally mean life or death. And having a consistent & reliable braking system can be accomplished by maintaining regular scheduled inspections of your brake system, you can not only prevent possible accidents, but also significantly reduce your cost-per-mile. While there is no specific time frame on how often you should inspect your brake system, with regular preventative maintenance and your eyes always on watch, you can reduce the costly downtime by spotting problems before they happen.

In this article, we will uncover some of the most common brake drum issues and the procedures for correcting the problem.

  1. What Are Brake Drums?
  2. 7 Common Brake Drum Issues & How To Correct
  3. Wheelco Recommendation

What Are Brake Drums?​

The drum braking system has been around for quite some time and is known as the grandfather of braking systems. Brake drums are used in many industries such as automotive, commercial, and industrial and come in a wide variety of sizes and designs. 

Drum brakes feature a simplistic design and not much has changed since it was patented in 1902 because the concept is simple, and it works! Drum brakes work by using friction and this is achieved by utilizing a force to push brake shoes against the inside of the brake drum to slow down the wheel. The force used to push the brake shoes to the drum can be accomplished by different methods such as air or hydraulic force. Hydraulic force is accomplished by using a fluid that is forced into wheel cylinders which in turn push the brake shoes to the brake drum. Air brake systems utilize compressed air to create a motion to force the brake shoes to the brake drums. Learn more differences between brake drums and air disc brakes in this article that helps you choose the best type of brake for your vehicle. Overtime, the drums will wear out and need to be replaced but they almost always show signs to alert you when a problem has occurred.

7 Common Brake Drum Issues & How To Correct Them

There are a few easy signs that you should be on alert for to know when your brake drums need to be brought in for service. By using your senses, you will know when your braking does not feel right. When you brake, you should expect a firm resistance coming from the pedal as your brakes are activated. Listen for noise as your brakes begin to activate and slow your heavy duty truck down. If you experience a sudden shuddering feeling or you don’t slow down as quickly as you believe you should, you will need to remove your brake drum and look for these 7 common brake drum issues.

  1. Cracked Drums
  2. Heat-Checking Drums
  3. Grease-Stained Drums
  4. Blue Drums
  5. Polished Drums
  6. Out-Of-Round Drums
  7. Excessive Wear on Drums

Cracked Drums

Photo Credit: Webb | Common Warranty Claims

Cracked drums can be caused by excessive heating and cooling of the brake drum during operation. You will see a crack extending through the entire wall when inspecting your brake drum if yours is cracked. You should not operate your vehicle at all if you have a cracked drum. You should immediately replace the cracked drum and check for proper brake system balance and proper brake lining friction ratings as recommended by the OEM.

If you notice repeat cracking of the brake drum, it could mean a few different things. The repeat cracking could be caused by an inadequate brake system or brake drum for your application. If the drums, lining, and brake system are all correctly rated for the vehicle and application, then the cracking could be a sign of driver abuse.

Heat Checking Drums​

Heat checking is a common condition that shows the appearances of several short, fine, hairline cracks on the drums braking surface. These cracks are caused by constant heating and cooling of the braking surface while the brakes are applied during operation. Heat checks will normally wear away with time as you continue to apply your brakes. However, heat checks can also progress further over time into full cracks in the braking surface. If you find heat checks, you should further inspect for deeper cracks, as it is not advised to drive your heavy duty truck with a cracked drum.

Photo Credit: Gunite | Heavy-Duty Brake Drums Maintenance & Installation Manual

Replace the brake drum if any of the following conditions are found: one or more heat check that extend completely across the brake surface. Heat check cracks that are 0.06 inches wide and/or 0.12 inches deep or greater.

Grease-Stained Drums​

If you find discolored spots on the braking surface of the drum, you may have a leaky wheel seal, or this could result from improper greasing of the brake cams. You can know for sure if you have grease-stained drums by checking for oil and grease spatter near the brake assembly.

If you find oil and/or grease, you will need to locate where the leak is coming from to make repairs and eliminate the leak. You should also remove the whole brake assembly to clean each component entirely. For precaution, you should also replace any oil or grease-soaked linings.

Blue Drums​

A braking surface of a brake drum that is showing signs of bluing is usually caused by extremely high temperatures. This sign of extremely high temperatures could be caused by continuous hard stops, brake system imbalance, or improperly function return springs. While the heat may have changed the drums color, you may not need to replace the drum as long as it remains withing the allowable tolerance for operation.

To correct the bluing problem, the brake system first needs to be checked for proper balance. Next, the return springs should be evaluated if they are weak or broken. Lastly, the brake should be checked for proper adjustment and clearance. More serious issues will arise if a blue drum is left unresolved.

Photo Credit: Gunite | Heavy-Duty Brake Drums Maintenance & Installation Manual

Polished Drums​

Polished drums will have a mirror-like finish on the braking surface. It is a normal procedure to sand the braking surface of the drum at the time of relining. If you see a polished mirror-like finish on the braking surface of your drum, check for lightly dragging brakes and then use some 80-grit emery cloth to sand the braking surface. You should also remove the glaze from the linings by using the 80-grit emery cloth.

Out-Of-Round Drums​

If your drum diameter has different measurements at different points around the braking surface, you have an out-of-round drum. Having an out-of-round drum can be caused by several reasons. The most common cause of out-of-round drums is distortion from excessive heat that is created during the braking process. It could also be caused by improper chucking of the drum during turning or dropping of the drum or even a result of improper storage techniques.

Another common cause is incorrect assembly installation. A lot of drums currently being produced are “hub” piloted, as opposed to the traditional “stud” piloted drums. This means that the pilot of the brake drum is centered on the hub. If these two surfaces are not are not properly flush or centered, this can cause an out of round drum. If this happens, the drum’s mounting pilot will have an indentation from the hub-pilot mating surface. The drum could possibly be machined if it does not exceed .120” over the original diameter. If your drum does exceed .120” over the original diameter, then your drum will need to be replaced.

Photo Credit: Webb | Common Warranty Claims

Photo Credit: Webb | Common Warranty Claims

Excessive Wear on Drums​

Excessive wear can occur along the edges of the lining of the braking surface or near the lining rivet holes. You should always look for buildup of the abrasive material. In fact, the most common cause of excessive wear on the drums is built up abrasive material because of a dust shield or lack of dust shields. If you have a dust shield and experience excessive drum wear, then it is most likely due to the lower dust shield blocking the material from exiting the braking system. Simple fix to this issue is to remove the lower dust shield. But if you are noticing excessive drum wear without a dust shield, then abrasive material is probably entering the braking system. Again, the simple fix to this is to attach a dust shield which will help stop the abrasive material.

Wheelco Recommendation​

At Wheelco, we only carry high quality products that meet our customer’s heavy duty needs. For brake drums, we recommend a top quality brand between Gritline, Webb, and Gunite.

Gritline parts are affordable and reliable for your trucks and trailers. You expect truck and trailer parts to be engineered for your toughest, heavy duty jobs and Gritline meets those expectations. Gritline offers smart solutions for your complex needs of the heavy duty industry. When you purchase a Gritline brake drum, know that you are getting a quality and reliable brake drum that stands up to today’s rigid industry standards. You can count on Gritline.

Webb Wheel Products has over 60 years in the heavy duty industry of manufacturing quality OEM and aftermarket brake drums. Webb takes great pride in their commitment to research, development, and testing. Webb continues to innovate. Made in the USA using high-grade cast iron for durability, Webb trailer brake drums also benefit from this dedication of engineering by offering the Vortex CRT line of brakes that use greater braking mass and has external cooling ribs to lower operating temperatures and offer 25 percent longer life.

Gunite brake drums offer consistent performance, safety, and quality, making it a clear choice for your brake drum needs. Available for any application, OEM-standard, lightweight, bus or transit, heavy-duty, or aftermarket, Gunite produces full-cast brake drums to meet the demanding requirements at a lower price than OE-original brake drums.

Visit with our Wheelco team of aftermarket experts and service techs to help find the brake drum that meets your application needs. Give us a calltext, or message us through chat to get started, or stop in to one of our stores today.

About Wheelco Truck & Trailer

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Customer driven is more than just offering you advice, giving time-honored service or contributing the latest tech-support. It’s about being there—whenever and wherever you need us—in-person, over the phone or online.

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