i have a sqeaking noise coming from my front wheeon my 59 n-tec,sounds like metal on metal. this only happens after driving for 1/2 hour, and after stopping for an hour the problem stops. the noise isn't there when iuse ther brakes and when i turn the wheel to the left it is there. the brakle servo has been changed although this has not solved the problem. does anybody have any clues as how to slove this? the garage is strugglig to solve it.