There are two types of hydraulic brakes that your vehicle can have, and in some cases, you may have both options at work in your car. The most common style of brakes is the disc brake that works off the brake pads pressing in towards the rotor and the friction will cause the car to slow and stop. The second option you can have is drum brakes, where the brake shoes are inside of the brake drum and will press out to cause friction against the brake drum resulting in slowing and stopping of your vehicle. Unlike disc brakes that can be found on all 4 corners of a vehicle, you will only find drum brakes on the rear axle of some vehicles.
Drum brakes were the first brake design invented in 1899 by Wilhelm Maybach and utilized by Gottlieb Wilhelm Daimler. The names “Maybach” and “Daimler” are recognizable today and emblematic of two pioneers of the automotive industry. Although disc brakes were similarly around for decades, it wasn’t popularized until 1953. In this year’s infamous Le Mans race, Jaguar equipped its’ racecar with a disc brake system that outperformed competitors in situations where high speed vehicles needed to decelerate quickly. The rest is history as disc brakes have become the standard style in cars, SUVs, and trucks today.
Brake System Operations
The brake pedal in your car is connected to a piston inside the brake master cylinder, so once you begin to depress that pedal it will, in turn, start pushing the brake fluid inside of the master cylinder where it will then flow to the slave cylinders at each wheel. Keep in mind, the fluid cannot compress therefore movement within the system is tied to a hydraulic force. Once the fluid is inside the slave cylinder, that is when it will start pressing the pistons inside the brake caliper against the brake pad. That forces the pad against the brake rotor to create friction, ultimately slowing the vehicle. Similarly, in a drum brake system, the wheel cylinders that are filled with the brake fluid will push against the brake shoes forcing them outward to the brake drum to slow the vehicle upon contact. Both systems depend on a friction material that is a wearable component, hence, brake replacement and repair being a central part of regular vehicle maintenance.
Drum vs Disc Brake Systems
One of the reasons why disc brakes are the preferred style is their ability to self-clean compared to drum brakes. Drum brakes house the wheel cylinder and the brake shoes inside of the drum, thereby trapping substantial residual dust which is a normal friction byproduct of brake operations. Due to this, drum brakes often require some disassembly to manually clean and adjust the brake shoes and drums. In contrast to drum brakes, disc brakes are exposed and often visible through the wheels as the brake pads on a disc brake system make contact with the rotor, it is also wiping clean any dust that comes off the brake pads during that slowing event. This self-cleaning feature is a positive for the system. However, there are downsides. Notably, external debris including rocks could get stuck between the brake pads and rotors causing squeaking or potential damage to components of the brake system. Another reason why disc brakes are a preferred style is their ability to dissipate heat due to its exposure to outside elements. When brakes get hot you can experience several concerns, such as the rotors and drums warping, brake pad or shoes glazing, as well as brake fade. Colorado drivers going to and from the Rocky Mountains are very familiar with premature brake wear yet also understand the importance of maintaining the integrity of the brake system.
Symptoms of Brake Problems
The most common symptoms of brakes that have overheated are the rotors or drums warping due to the metal getting so hot it no longer holds its perfectly flat friction surface. When brake rotors or drums warp you can feel a slight pulsation in the brake pedal as you are depressing it. This pulsation is caused by the feeling of the friction material bumping up and down with the imperfections in the rotor or drum. The second most common symptom of brakes that have been overheated is glazing on the brake pads or shoes. This means the part of the brake pad or shoe that is the friction point has started to melt together and become soft therefore not allowing it to grab at the rotor or drum as designed.
Another symptom of a brake system needing inspection or repair is brake fade. This is caused by the brake fluid getting excessively hot and gaining some viscosity, therefore slowing how freely it moves to allow the application of pressure to the brake pads. Brake fluid is hygroscopic meaning it will over time absorb some of the moisture in the air. Brake fluid is typically clear in color, and you can tell when your brake fluid is starting to absorb too much water because it may have a slight green or brownish tint. When brake fluid absorbs too much water, it will be prone to boiling and not being able to transfer the pressure needed to apply the brakes.
An immediate way to avoid brakes from overheating is to downshift whenever possible. This puts the burden of slowing down on the drivetrain instead of the brake system. One can also invest in drilled and slotted rotors which are designed to have air channels, allowing more air flow during engagement which results in cooling the brakes. Even if a driver does not invest in drilled and slotted rotors, replacing brake components with high quality OE or OE-equivalent parts is important. This is not a system to cut corners and buy cheap parts. Finally, brake fade can be addressed by servicing your vehicle’s brake fluid every 1-2 years and this is achieved by a brake fluid flush at a local repair facility that possesses specialized equipment. That shop should be able to identify if a vehicle requires DOT3 or DOT4 fluid. Any mechanic that says those fluids are the same should not call themselves a mechanic! Each vehicle has unique fluid specifications that engineers took into consideration when developing the architecture for each vehicle’s braking system. DOT3, for example, absorbs less water over time, however, DOT4 has higher dry and wet boiling points allowing better performance in higher temperatures. Fluid characteristics and brake systems can get complex quickly, so why not trust the experts?
Local & Honesty Independent Auto Repair Shop
Do not trust your brakes to any mechanic. Your brake system is what protects you and your family from harm so find a reputable local repair shop that will prioritize the safety and reliability of your vehicle, rather than view you as dollar bills! At Hotchkiss Auto Repair, we have treated customers with honesty and integrity for decades. Our certified technicians will perform industry leading inspections, maintenance activities, or repairs so you can drive confidently regardless of if it’s to work in Park Hill or to one of Colorado’s world class ski resorts. Call us today at 303-780-7747 to schedule an appointment.