I just installed the red stuff front brakes. The car stops great but for some reason when i'm coming to a stop (5mph or less) i get this high pitched "whistle" noise. It's not the typical brake squeal noise but more of an annoying and very loud "whistle." Anyone experience this or know what the noise can be? It happens mostly when the brakes are cold and during my first couple of stops. The noise seems to diminish or go away once the brakes get warmed up. Thanks in advance.

 

Brake pad material does not simply "rub" the braking surface. On a small scale, it actually grabs and moves with the rotor for a small distance, then lets go, then grabs again, etc.. This is called "stiction". It results in vibration. All brakes "squeal", whether or not you can hear it depends on whether or not the frequency is in the audible range. This is dependent on the materials involved, the tolerances of bolts in the mounting hardware, etc. Commonly there is a backing plate between the pad and the caliper piston and a small amount of grease in between. This helps isolate the vibration of the pads from the rest of the hardware. Also, check into "bedding in" of the pads, which will change the material properties of the pad and rotor surfaces. Also ensure that the prescribed lubrication, if any, is applied to the appropriate bolts, bushings, etc., of the caliper mounting.

 

I didn't really "bed" the pads.. i just made sure i didn't abuse them at first. However, i'm thinking about bedding my brakes now if it's not too late.. My braking is smooth its just that that this loud and high pitched whistle noise that drives me nuts when the brakes are cold..