squeak and squeal
I was going to go on about the amount o fmetal in pads today - bu tI found this on a brake manufacturer site (brakewarehouse.com) which does ring true when I used to work on cars.. !
in the old days you would get alot of squeal from the back of the pad vibrating on the piston inside the caliper. Hence the old trick of using copper grease (high temperatures would boil any other) smeared lightly on the back of the pad where it comes into contact with the piston.
from the site..
Myth
Metallic pads cause more brake squeal than non-metallic pads.
Reality:
Don’t blame the pads. Brake squeal is caused by vibrations between the pad and rotor. When the vibrations are in an audible range, you hear a squeal-like sound because of the rotation of the system.
Vibration has many causes: (1) malfunctioning caliper, (2) warped rotor, (3) fatigued or missing brake hardware, (4) unlubricated metal-to-metal surfaces in caliper and brake hardware, (5) pads and rotor not burnished in, (6) malfunctioning brake booster, and many other brake system failures.
In fact, some brake systems are prone to squeal problems, and that is why most systems use brake-silencer shims. It is very important to do a complete brake job and not merely replace the pads or pads and rotor. All brake hardware should be replaced at the same time as the pads and a proper caliper grease applied to all metal-to-metal surfaces. The pads and rotor must be burnished in during the road test.
Don’t blame the pads. Brake squeal is caused by vibrations between the pad and rotor. When the vibrations are in an audible range, you hear a squeal-like sound because of the rotation of the system.
Vibration has many causes: (1) malfunctioning caliper, (2) warped rotor, (3) fatigued or missing brake hardware, (4) unlubricated metal-to-metal surfaces in caliper and brake hardware, (5) pads and rotor not burnished in, (6) malfunctioning brake booster, and many other brake system failures.
In fact, some brake systems are prone to squeal problems, and that is why most systems use brake-silencer shims. It is very important to do a complete brake job and not merely replace the pads or pads and rotor. All brake hardware should be replaced at the same time as the pads and a proper caliper grease applied to all metal-to-metal surfaces. The pads and rotor must be burnished in during the road test."