If you get a very loud metallic grating sound, then the odds are you have a stone stuck in a brake disk. If it doesn't pop out it a few miles, it may stay there forever, grinding and clanking away.
- Slacken the wheel nuts off half a turn.
- Jack the car up and remove the wheel.
- Have a look at the photos below - the stone should be at the bottom. You need to move the bottom of the disk outwards slightly to release it, so:
- Unscrew the 2 large screws holding the disk on.
- Carefully ease the bottom of the disk outwards, just enough to let the stone drop out.
- Be careful, as the disk is still between the calipers, and you don't want to damage anything.
- Replace everything, making sure both the disk and the wheel are well located when you do them up.