The "crunch of irons" that you say, is usually that a pill is spent and you are braking iron with iron, destroying the disc, check them and change them, as well as the brake discs (because if it has been damaged 1, you have to change both of the same axis), the vibrating may be that when the pills are spent the gag, surely it is also corrected when the new pills are corrected. Greetings!!