Signs you need brakes
- A high-pitched squeal when braking. Many pads have a small metal wear indicator that makes this sound on purpose.
- Grinding or growling. That often means metal-on-metal contact, so stop driving and get it inspected. You may be damaging the rotors.
- A pulsing brake pedal or a steering wheel that shakes when you brake. Often warped or unevenly worn rotors.
- The car pulls to one side when braking, or a soft, spongy, or sinking pedal. Those can be hydraulic problems, so get them checked promptly.
- A brake warning light on the dash.
How to check pad thickness
New pads typically have around 10–12 mm of friction material. Look through the wheel spokes at the caliper. You can see the pad's edge pressed against the rotor. If the material looks about as thick as a couple of stacked coins (roughly 3 mm) or less, plan a replacement. Inner pads often wear faster than outer ones, so check both if you can.
Pad types compared
| Type | Best for | Trade-offs |
|---|---|---|
| Ceramic | Daily driving, commuters | Quiet and low dust with a long life. Costs more, and the initial bite in extreme cold or heavy duty is less aggressive. |
| Semi-metallic | Trucks, towing, performance | Strong bite and heat tolerance, but more noise and dust and more rotor wear. |
| Organic (NAO) | Light, older, low-demand vehicles | Quiet and cheap, but they wear faster and fade sooner under heat. |
When in doubt, match what your vehicle maker specifies. Many stores look this up by year, make, model, and engine.
Do you need new rotors too?
Every rotor has a minimum thickness stamped on it. If it's below that, has deep grooves, has heat cracks, or causes pedal pulsation, replace it. Rotors are often replaced or resurfaced with the pads, and on many modern cars replacing them is about as cheap as machining them. Replace rotors in axle pairs too.
DIY tips
- Loosen the lug nuts on the ground, then lift the car with a jack and support it on jack stands. Never work under a car held up only by a jack.
- Do one side at a time so you have a reference for how the clips and hardware go back together.
- Use new abutment clips/hardware if supplied, and lube the slide pins with brake-specific grease. Keep grease off the friction surfaces.
- Pump the pedal several times before driving to push the pistons back out against the pads.
- Torque lug nuts to spec in a star pattern.
- Bed in new pads as the pad maker directs. This usually means a series of moderate stops from speed without coming to a full stop, then driving to cool.
Brake fluid: check the level and condition while you're there. Most cars use DOT 3 or DOT 4 (glycol-based). Never add DOT 5 (silicone) to a system that uses DOT 3/4/5.1. Your manual and reservoir cap say which one to use.
FAQ
How often should brake pads be replaced?
Should I replace brake pads on all four wheels?
Are ceramic brake pads better?
References
This guide is general information, not professional repair advice. Always follow your vehicle’s owner’s manual and service specs, and use proper safety equipment.