Worn Out Brake Pads: Signs of Bad Brake Pads and What to do Next
Virtually all cars on the road today have disc brakes on the front. Although some have drum brakes on the rear axle, most also use a disc brake design at the rear wheels too. When the brake pedal is pressed, fluid in the system creates hydraulic pressure in the brake lines and hoses, and a piston in the brake caliper mounted to the wheel knuckle extends around a brake rotor. It squeezes an inboard and outboard brake pad against the flat sides of the rotor, and the friction material on the pad grips the metal surface and forces your car to slow down. It’s this friction that causes worn out brake pads.
It takes tens of thousands of miles to wear out a set of pads – for most drivers it’s between 20,000 and 40,000 miles – but eventually they’ll need to be addressed. Determining when brake pads are worn out is a crucial first step, followed by dealing with the appropriate repair.
How Do I Know if My Brake Pads are Worn Out?
Brake pads all have a solid steel backing plate to which the friction material is bonded. There are three different types of pad material you’ll find for most passenger vehicles:
- Non-metallic or organic brake pads have a blend of synthetic materials like cellulose, sintered glass, aramid, and other compounds in various quantities depending on the manufacturer. They’re quiet and a relatively soft material so they aren’t hard on rotors but have a shorter lifespan than other options.
- Semi-metallic brake pads are a combination of metals like copper, steel, and iron mixed with non-metallic compounds like graphite and fillers. They’re longer lasting but can be noisy at times and generate more wear on the rotors.
- Ceramic brake pads combine elements like clay and porcelain with copper fibers for quieter stopping, long wear life, and resistance to rotor wear.
Regardless of what material your brake pads are made of, they’re eventually going to wear out. The best way to determine if your brakes are worn out and need to be replaced is with a visual inspection. When the wheel has been removed, both the inner and outer brake pad thicknesses should be measured at each end to see who much material is remaining.
Most brake pads are manufactured with between 8/32” and 12/32” of wear material, not including the backing plate. When the remaining material is down to 3/32”, it’s time to replace your brake pads. If you continue to drive, you could notice symptoms of worn brake pads worsen when the material is at or below 2/32”.
Signs Your Brake Pads are Worn
- Squealing when you stop. Many brake pads have squealer tabs that touch the rotor to make noise as a warning sign your pads are low.
- Grinding when you drive and brake. If the brake pads are worn out, the backing plate can contact the rotor and exhibit metal-on-metal grinding noises as well as a rough feeling in the brake pedal.
- Extended stopping distances. The friction material helps you slow down sooner, and worn-out brakes often aren’t as effective.
- Grooves in the rotor surface. You can often visualize the rotor between the wheel spokes, and deep grooves indicate your brakes are worn out.
- Pulsation in the pedal. You might feel the brake pedal kicking back at you rapidly as you try to brake from high speed.
- Pulling to one side. If brakes are worn out on one side only, braking is uneven and can pull you to one side or the other.
How Long Can You Drive with Worn Out Brakes?
It’s technically possible to drive with worn-out brake pads with increasingly poor application as the material grinds away. If you have 4/32” friction material left, it could be thousands of miles or months before any safety-related concerns show up. Once they do, however, you could be in a situation where your brakes no longer perform as designed.
When 2/32” material remains on your brake pads, any mechanic will strongly encourage you to replace them immediately. In some states like Virginia, worn brakes won’t pass a safety inspection at this level. Not only could you be sidelined from brake failure, but ignoring the repair could take your car off the road until they’re replaced.
Left unfixed long-term, brake pads will eventually wear into the rotors, forcing you to replace them as well. The caliper piston could over-extend or contact the rotor surface in extreme situations, requiring new calipers too. Altogether, it’s simply unsafe to drive for long without changing worn brake pads.
Replacing Worn Brake Pads
Most DIYers will give a brake job a shot at home. It requires some common tools that you’ll find around a well-equipped garage including:
- A floor jack and wheel chocks
- A lug nut wrench
- A socket and ratchet set
- A large C-clamp or caliper compression tool
- Flat screwdriver
- Silicone-based brake lubricant
- Brake cleaner spray
- Eye protection and gloves
Changing your own brake pads is a pretty straightforward job and also a great way to save on cost. Now that you have identified that your brake pads are worn out, you can learn how to change your brake pads in our step by step guide.
