I am getting an unusual ticking noise while braking after doing a recent brake job front and back on my 02 wrx. I put on new brembo blanks and hawk hps pads both front and back. The brakes were properly "bed in" and the car brakes normally whether routine stopping or emergency stopping with the new pads/rotors. I did not disconnect any lines so bleeding was not needed. I have done brakes on this car 3 times before with no issues. Aside from the noise all seems fine. The noise is only heard when braking at low speeds. When not braking there is no noise, and at high speeds (30+) all seems normal. The volume of the tick increases with the brake pressure and the rythm of the ticks frequency is directly related to the cars speed, i.e. more ticks per second the faster I am going at the time, the frequency slows as I come to a stop. It sounds like a nonmetallic noise, almost as if someone was taking a small rubber mallet and tapping it on a thick (damped) piece of metal. After the car has warmed up for about 10 minutes the ticking noise stops altogether.
I am not positive if it is coming from front or rear, though it seems more like the rear. I pulled the rear brakes apart last night to inspect and could not find any contact points that could be making the noise. What I did find that was that on one side the rubber gasket/boot (sorry not sure of proper term for the rubber part around the piston is) surrounding the piston on the caliper was all "crinkled". It was not neatly folded up in the circular pattern that a normal caliper piston boot/gasket is. I took a picture, sorry if it is a little out of focus, seemed more clear when I took it. There is no fluid leaking from the caliper (red material is brake grease) and there is no sponginess in the brake pedal, so leads me to think all is fine? Could this be causing the noise issue? If it is not causing the noise issue is it something that warrants replacing the caliper? Attachment 101919
My last set of rotors had gotten way below the minimum thickness, not sure if that could be causing any of this? Also when doing the rears, I was stupid and had the ebrake on while trying to get the rear rotors off...yes i know . Anyways I tried pulling on the rotor for a good 5 minutes before realizing this. Could I have damaged the e-brake in a manner that would make noise when the normal brakes are engaged how I described above?
Anyways I will be pulling apart the fronts tonight or tomorrow and am hoping that maybe someone has run into this issue before and can point me in the right direction or suggest some potential causes. Thanks!