Abstract：If you’ve noticed a “spongy” feeling when applying your brake pedal, that your brake drums are blue or out of round, you may have an overheating brake drum.
A brake drum is a wide yet short cylinder attached to the wheel. When the brakes are engaged, the friction material on the brake shoes (or pads) makes contact with the brake drum to slow down or stop your vehicle.
As a result, brake drums get hot through regular use.
But occasionally, they can overheat.
Next we'll discuss why brake drums get hot, how overheating drums can affect your car, and answer some common FAQs.
This Article Contains
Brake Drum Hot to Touch?
Why does this happen?
How Does an Overheating Brake Drum Affect Your Car?
What Should I Do If My Brake Drum Heats Up?
How Can I Prevent an Overheating Brake Drum?
Hot Brake Drum FAQs
Brake Drum Hot to Touch?
Brake drums become hot because of friction. The brake system converts kinetic energy into heat energy through contact between each brake shoe and the drum. This contact is what reduces the turning of the wheel.Typically, hot brake drums range in temperature from 150°F to 400°F when operating. But sometimes drum brakes can overheat, reaching temperatures of 600°F or more.
Why does this happen?
Besides aggressive driving, there are three main causes:
1.Incorrect adjustment: Poorly adjusted brakes can cause excessive contact between the brake drum and brake shoe. In extreme cases, poor brake adjustments can cause the rear wheels to lock up.
2.Seized wheel cylinder: Over time, failing dust boots make the wheel cylinder rusty or dirt-filled. The dirt or rust then causes the pistons to seize, keeping the brake shoes in contact with the drum. This is known as brake drag.
3.Warped brake drum: The surface of the drum is either uneven or rough due to the accumulation of dirt and brake pad material. This is typically a result of high temperatures related to strong braking.
Note: A faulty wheel bearing can cause your brake drum to get hot, too. The bearing connects the wheel to the axle and enables the wheel to rotate smoothly. However, a faulty wheel bearing could cause the wheel hub to turn extremely hot, and this heat could transfer to the brake drums.
How Does an Overheating Brake Drum Affect Your Car?
Mostly, the heat from braking doesn’t affect your vehicle significantly. But, in extreme cases, overheating brakes can impact your car in several ways:
1. Abnormal Brake Functioning
There are three ways in which overheating brake drums can affect brake functioning:
Fading brakes: “Brake fade” refers to the reduced stopping power of the brakes due to repetitive use. If this happens, your brake pedal may feel “spongy.” A spongy brake may also be the result of hot brake fluid.
Squealing brakes: When the brakes get worn, they can often squeal when the metals grind together during braking.
Smoking brakes: Smoke can often result from excessive heat. You may also notice a burning smell accompanying the smoke.
2. Cracked Brake Drum
Extreme braking creates a continual heating and cooling cycle that can stress the brake drum metal — and your brake drum can eventually crack under braking force.
When it comes to cracked brake drums, there are two likely causes: slamming on the brakes at high speed and a skewed brake system. It’s always a good idea to examine your brakes for heat checks or major cracks, especially if you apply your brake aggressively.
3. Heat Checking Drums
“Heat checks” refer to small, thin cracks on the drum brake surface. They are a result of repetitive heating and cooling of the brake system.
What Should I Do If My Brake Drum Heats Up?
While normal heat in a drum is nothing to worry about, you should immediately stop driving if you notice an overheating brake. Ideally, you should have your car towed and repaired by a reputable mechanic.
But what if I have to drive?
Keep a low speed to compensate for the lack of braking power, and take your car to a mechanic ASAP.
If your brakes fail while driving, you may have to apply the parking brake(emergency brake or e brake) to slow down and stop your car.
How Can I Prevent an Overheating Brake Drum?
Generally, good driving habits will prevent your brakes from overheating. Essentially, anything that reduces pressure on your brakes, including:
Leaving enough distance to brake slowly
Avoiding slamming your brakes
Using engine braking when driving downhill
6. Hot Brake Drum FAQs
Here are answers to some common brake drum FAQs.
1. How Do Brake Drums Work?
When the brake pedal is applied, the master cylinder converts the pressure from the brake pedal to hydraulic pressure. The pressure pushes the pistons, which, in turn, presses the brake linings into the brake drum. This causes friction which serves as a stopping force on the wheel.
2. Is an Overheating Brake Drum Dangerous?
Excessive heat in the brake drum can cause brake fade, essentially reducing braking ability.
Brake fade is more common in drum brakes, as their closed design traps heat more than a disc brake.
3. What are the Other Signs of Overheating Brake Drums?
Typically, other signs of overheating brake drums include smoke and a burning smell.
In addition, you may notice your brakes squealing when they are in use. This is often because of “glazing,” which refers to early brake wear and a loss of braking friction.