Diagnosing a set of worn brake pads is pretty easy. Generally, all you need are your eyes and a few simple tools.
Note: The following is a general guide for educational and entertainment purposes only. Consult your vehicle’s factory information for specific repair instructions and recommended safety procedures.
Inspect the Pads for Wear and Damage
Inspecting and measuring your brake pads is the best way to go. Sometimes, you can peek through your car’s wheel with a flashlight to perform a cursory inspection of the pads. But the most thorough method involves the removal of your wheel/tire assembly and checking the brake pads for minimum thickness and physical damage. Here’s how it’s done:
1. Put on your safety glasses.
2. Safely raise the vehicle and support it with jack stands.
3. Remove the wheel and tire assembly.
4. Remove the brake pads from the caliper.
Note: You can usually measure thickness without removing the pads from the caliper. In this article, however, we are also checking the pad friction lining for physical damage, which requires pad removal.
5. Use either a brake pad thickness gauge set or a digital caliper to measure the thickness of the pad.
- Use your tool to measure the amount of friction lining from the backing plate to the top of the pad. Be sure to measure both the inner and outer pads at several points.
- Replacement is generally recommended if the amount of friction material left on the pad is 4mm or less at any point. Some professionals recommend replacement at 6mm or less.
- If the measurement is 3mm or less at any point, the pads should be replaced immediately. The pads should also be replaced if they show signs of significantly uneven wear.
6. In addition to measuring pad thickness, you’ll want to check the friction lining for physical damage that would warrant replacement, such as:
- Contamination (from fluids or grease)
- Cracks and large chips
If the pads look worn or damaged, you’ll want to replace them right away.
On the other hand, if the pads look good, you can put everything back together. Once everything is reassembled and the car is back on the ground, pump the brakes several times to ensure they feel firm. DO NOT drive the car until the brakes feel solid.