* Worn Brake Pads: This is the most common cause. Worn pads expose the metal backing plates to the rotors, causing a grinding sound. This is a relatively inexpensive fix requiring only new brake pads.
* Worn Brake Rotors: If the pads are worn down to the metal, the rotors (brake discs) may also be damaged. Grooves or scoring on the rotor surface can cause grinding. Worn rotors may need resurfacing or replacement.
* Brake Caliper Issues: A seized or sticking caliper piston can cause uneven brake pad wear, leading to grinding. A caliper rebuild or replacement might be necessary.
* Parking Brake Issues: A problem with the parking brake mechanism, such as a seized cable or improperly adjusted shoes (if it's a drum brake system – less common on the rear of a newer Golf), can also produce a grinding sound.
* Foreign Object: Something might be lodged between the brake pad and rotor, causing the grinding.
* Wheel Bearing: While less likely to be specifically related to braking, a failing wheel bearing can sometimes make a grinding noise that's exacerbated when braking. This is a more serious issue than brake pad wear.
What you should do:
1. Do NOT continue driving with this noise. Driving with severely worn brakes is dangerous and can lead to brake failure.
2. Have a mechanic inspect the rear brakes immediately. This is not something you should attempt to fix yourself unless you have significant experience working on brakes. Improper brake repair can be very dangerous.
3. Describe the noise clearly to the mechanic: Tell them when the grinding occurs (only when braking hard, at low speeds, all the time, etc.). The more information you provide, the easier it will be for the mechanic to diagnose the problem.
Ignoring the grinding noise could lead to a serious accident. Professional attention is needed as soon as possible.
