Understanding Brake Pads and Rotors

Brake pads and rotors are two of the most important parts of a disc brake system. Together, they create the friction needed to slow or stop your vehicle. Understanding how they work—and when they need replacement—is essential for safe driving (Erjavec & Thompson, 2019).

What Are Brake Pads?

Brake pads are components made of high-friction materials that press against the rotors to generate the force needed to stop the wheel.

Types of Brake Pad Materials

Organic

Quiet and affordable, but wear out quickly.

Semi-metallic

Durable and good for performance, but noisier.

Ceramic

Long-lasting and quiet, with less dust, but more expensive.

Signs You Need New Brake Pads

1. Squealing noise when braking

2. Longer stopping distance

3. Brake pad warning light (on some vehicles)

4. Less than 3mm of pad thickness

What Are Brake Rotors?

Rotors (also called brake discs) are the spinning metal discs that your brake pads clamp onto to slow the vehicle down.

Types of Rotors:

Solid Rotors

Basic type, used in lighter vehicles.

Vented Rotors

Two layers with vents between them to help cool faster.

Drilled/Slotted Rotors

Help remove heat, gases, and water—used in performance or high-speed applications.

Signs of Worn or Damaged Rotors

1. Pulsing or vibration when braking

2. Grooves or scoring on the rotor surface

3. Squeaking or grinding noises

4. Visible rust or warping

How Pads and Rotors Work Together

1. You press the brake pedal.

2. Hydraulic pressure pushes the caliper pistons outward.

3. The caliper squeezes the brake pads against the rotor.

4. Friction slows the rotor, which slows the wheel and the vehicle.

Real-World Example

If you delay replacing worn pads, the metal backing can grind into the rotor—causing expensive damage and reduced braking performance.

Key Takeaways

Brake pads and rotors are wear-and-tear items—they must be inspected and replaced regularly.
Keeping them in good condition ensures effective, smooth, and safe braking.
Ignoring warning signs can lead to bigger repair costs and safety risks.

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References

Erjavec, J., & Thompson, R. (2019). Automotive Technology: A Systems Approach (6th ed.). Cengage Learning.

Reimpell, J., Stoll, H., & Betzler, J. W. (2001). The Automotive Chassis: Engineering Principles (2nd ed.). Butterworth-Heinemann.

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