How To Check Your Break Pads

Brake pads are a critical safety component of any vehicle. Knowing how to inspect them yourself is an invaluable skill, saving you money, preventing potential accidents, and giving you a deeper understanding of your car's workings. This guide provides a comprehensive look at brake pad inspection, aimed at intermediate car owners and DIY enthusiasts. While we have a detailed brake system diagram available for download, this article focuses specifically on visual inspection and assessing brake pad wear.

Why Brake Pad Inspection Matters

Regular brake pad inspection serves several vital purposes:

Safety: Ensuring sufficient friction material remains to provide adequate stopping power. Worn brake pads drastically increase stopping distances, especially in wet or emergency situations.
Cost Savings: Catching wear early prevents damage to other braking system components like rotors (also called brake discs). Replacing rotors is significantly more expensive than replacing brake pads.
Performance: Healthy brake pads contribute to consistent and predictable braking performance.
Preventive Maintenance: Identifying potential issues before they escalate into major problems. For instance, uneven pad wear can indicate caliper issues or other suspension problems.

Key Specs and Main Parts

Before diving into the inspection process, it's crucial to understand the key components involved and the specifications to look for.

Main Parts:

Brake Pad: The friction material that presses against the rotor to slow the vehicle. It consists of a steel backing plate with a friction material bonded to it.
Rotor (Brake Disc): The rotating metal disc that the brake pads clamp onto.
Caliper: The assembly that houses the brake pads and pistons. The caliper applies pressure to the pads, forcing them against the rotor.
Piston: A component within the caliper that extends and retracts, pushing the brake pads against the rotor.
Shims/Anti-Squeal Plates: Metal plates designed to reduce noise and vibration during braking.
Wear Indicator (Squealer): A small metal tab attached to the brake pad that makes a high-pitched squealing noise when the pad material wears down to a certain point, alerting the driver to the need for replacement.

Key Specs:

Minimum Pad Thickness: This is the most crucial specification. Consult your vehicle's repair manual or a reliable online database for the specific minimum thickness recommended for your vehicle's brake pads. Generally, anything less than 3mm (approximately 1/8 inch) is considered unsafe and requires immediate replacement. Some pads may have a wear indicator embedded in the friction material, providing a visual guide.
Rotor Thickness: While not the primary focus of this article, inspecting the rotor for excessive wear or damage is also important. Rotors have a minimum thickness specification as well.
Surface Condition: Look for signs of scoring, cracking, or uneven wear on both the brake pads and rotors.

The Inspection Process: A Step-by-Step Guide

Follow these steps to safely and effectively inspect your brake pads:

Gather Your Tools: You will need:
- A jack and jack stands (never work under a car supported only by a jack!)
- Wheel chocks
- A lug wrench
- A flashlight
- A measuring tool (ruler or caliper)
- Eye protection (safety glasses)
- Gloves (optional)
- A flat-head screwdriver (for removing any debris)
Safety First:
- Park the vehicle on a level surface.
- Engage the parking brake.
- Chock the wheels opposite the ones you'll be working on.
Raise the Vehicle:
- Loosen the lug nuts on the wheel(s) you'll be inspecting.
- Use the jack to lift the vehicle at the designated jacking point.
- Securely place a jack stand under the vehicle's frame near the jacking point. Never work under a vehicle supported only by a jack.
- Lower the vehicle onto the jack stand.
Remove the Wheel: Fully remove the lug nuts and take off the wheel.
Locate the Brake Pads: Behind the rotor, you'll see the caliper, which houses the brake pads.
Visual Inspection:
- Pad Thickness: Use your flashlight to get a clear view of the brake pad. Look at the friction material thickness. Measure the thickness of the pad material remaining on the backing plate. Compare this measurement to the minimum thickness specification for your vehicle.
- Pad Condition: Examine the pads for signs of uneven wear, cracking, glazing (a smooth, shiny surface), or separation from the backing plate.
- Rotor Condition: Check the rotor surface for scoring, cracks, or excessive rust. Light surface rust is normal, especially after rain or periods of non-use, but it should disappear after a few braking applications. Deep grooves or warping indicate the need for rotor replacement or resurfacing.
- Caliper Inspection: Look for signs of brake fluid leakage around the caliper piston seal. This indicates a potential caliper failure.
- Hardware Inspection: Check the condition of the shims, clips, and other hardware. Replace any damaged or missing components.
Repeat for All Wheels: Inspect the brake pads on all four wheels.
Reassemble:
- Reinstall the wheel.
- Hand-tighten the lug nuts.
- Raise the vehicle slightly with the jack to remove the jack stand.
- Lower the vehicle to the ground.
- Torque the lug nuts to the manufacturer's specified torque using a torque wrench. Proper torque is essential to prevent wheel damage or loosening.
Test Drive: After reassembling everything, perform a careful test drive in a safe area. Pay attention to the brake pedal feel, any unusual noises, and the vehicle's stopping performance.

Real-World Use: Basic Troubleshooting Tips

Here are some common issues and their potential causes:

Squealing Brakes: Often caused by worn brake pads, but can also be due to glazed pads, debris trapped between the pad and rotor, or worn shims.
Grinding Brakes: Usually indicates that the brake pads have worn down completely and the metal backing plate is contacting the rotor. This requires immediate attention to prevent serious rotor damage.
Pulsating Brakes: Can be caused by warped rotors or uneven brake pad wear.
Pulling to One Side During Braking: Indicates uneven brake pad wear, a sticking caliper piston, or a problem with the brake lines.
Spongy Brake Pedal: Can be caused by air in the brake lines or a faulty master cylinder.

Safety Considerations

Brake systems operate under high pressure and involve potentially hazardous components. Always follow these safety precautions:

Brake Fluid: Brake fluid is corrosive and can damage painted surfaces. Clean up any spills immediately. It is also harmful if swallowed.
Dust: Brake dust can contain asbestos fibers (particularly in older vehicles). Avoid breathing in brake dust. Wear a respirator mask when working on brake systems, especially if you are unsure about the presence of asbestos.
Heat: Brake components can become extremely hot during and after use. Allow them to cool down completely before touching them.
Proper Lifting Techniques: Always use a jack and jack stands to safely lift and support the vehicle. Never rely solely on a jack.
Torque Specifications: Always torque lug nuts and other critical fasteners to the manufacturer's specified torque.

Conclusion

Regular brake pad inspection is a crucial part of vehicle maintenance. By following the steps outlined in this guide, you can confidently assess the condition of your brake pads, identify potential problems early, and ensure your vehicle's braking system is operating safely and effectively. Remember, if you are unsure about any aspect of brake system maintenance, it's always best to consult a qualified mechanic.

We have a detailed brake system diagram available for download to further assist you in understanding the intricacies of your vehicle's braking system. This diagram provides a visual representation of all the components, helping you to identify parts and understand their relationships within the system. It's a valuable resource for anyone interested in learning more about brake system maintenance and repair.