Today’s drivers are pretty comfortable with modern braking technologies. We’ve become so used to the advanced technology that makes slowing and stopping our cars possible that we take it for granted – at least until something goes wrong. Disc brakes are subject to a number of problems, as well as wear and tear, and if you’re hearing a grinding noise when braking, then you need to take action immediately.
How this system works:
The modern disc brake system is actually relatively simple to understand, although it does require a significant network of components in order to operate. For the purposes of this discussion, we’ll limit the scope to just the components mounted around the wheel hub – the ones that might be responsible for the grinding sound you’re hearing.
There are several components here – brake lines deliver pressurized fluid to the brake caliper, which holds and actuates the brake pads. Brake pads are made with a metal backing plate and a high-friction material on the other side. This material is designed to press up against the surface of the rotor, slowing and stopping the car as the caliper squeezes the rotor between the pads.
Over time, pads wear down. It’s a simple fact of life. You’ll need to replace them periodically, although the frequency of replacement will vary depending on your driving habits, local geography (hills, mountains, etc.) and other factors.
Common reasons for this to happen:
Excessive Pad Wear: The single most common reason to hear a grinding noise when braking is excessive pad wear. Once the material has been worn off the backing plate, you’ll be experiencing “metal on metal”. Part of the brake caliper could also be touching the rotor at this point. Both cause extensive damage – the backing plate will eat into the rotor, causing grooves and serious damage. The caliper will do the same thing, but the rotor will also eat into the metal of the caliper, potentially causing the need for replacement.
Foreign Debris Lodged in Brakes: It’s also possible to have foreign debris lodged in the brake system. The most common example would be a rock or piece of gravel caught in the caliper and riding between the caliper and the rotor. This can cause damage to the rotor as well, and you’ll generally hear the sound even when you’re not pressing the brake pedal.
Low Quality Brake Pads: If you’ve had your brake pads replaced recently and are now hearing a grinding sound, it could be because low quality pads were used. Semi-metallic pads can sometimes contain hard chunks of metal that will eat into the rotors and cause a grinding sound when applied (always use OEM quality brake pads).
Wear Indicator Contacting Rotor: If the sound you’re hearing is more of a squealing than a grinding, chances are good that it is the wear indicator on your pads connecting with the rotor. This comes preinstalled on many brake pads and is designed to warn you that the pad material is getting low and you’ll need to replace them soon.
What to expect:
One of our professional mobile mechanics will visit your home or office to inspect the brakes and determine if the problem is due to wear and tear, or if there is something deeper going wrong, such as the rotor being grooved by the caliper. The mechanic will then provide a detailed inspection report that includes the scope and cost of the necessary repairs.
How it's done:
The mechanic will inspect your brake pads, the rotors, calipers, and the brake lines feeding the calipers. It may be necessary to remove one or both front wheels for a visual inspection. It may also be necessary to test drive the vehicle if the source of the problem is not immediately apparent in order for the mechanic to verify the grinding noise.
How important is this service?
If you’re hearing a grinding sound when applying the brakes, there is definitely something that needs to be addressed. It might be something as simple as the wear indicators on the pads connecting with the rotor, or it could be something more serious. If you have worn completely through the pads and your brakes are now “metal on metal”, it’s essential to your safety to replace your pads and have the rotors resurfaced now. In some cases, the damage to the rotor may be severe enough to require replacement.