Hey guys. I know this thread is dead, but I never got around to actually doing anything about my brakes. Didn't try the sticky stuff or anything. But I've driven the car a bit and have some more information.
Something I have now remembered is that the issue started when I was in a gas station and went into reverse with the parking brake on a year ago. I released the parking brake and had the "sounds like a rock is stuck in there" really loud noise, I went back and forth a few times and it wasn't so bad. I drove along and the noise I have today started. I replaced the pads and rotors as previously mentioned so I know there isn't anything stuck in there.
I have noticed that after driving back to the house and I start to go in reverse to back into my driveway, the sound is MANY times worse than when going forwards. Painfully loud. This confirms that there is significant pressure being put on the rotor, not just the pad leaning on the rotor from gravity.
I've done the self adjustment procedure I've seen on the forum which is to yank on the handbrake with the button pushed 10 times or something with no difference.
The other information is that I am noticing that sometimes when I push the pedal at low speed in the driveway or parking lot, the car doesn't slow down for a moment, but actually feels that it accelerates for a moment. During that moment the sound goes away, then comes back in normal fashion as brake pressure is applied (the pads are supposed to make noise when there is light pressure since they are race pads). This makes me feel that it is a parking brake issue and that pushing the pedal is actually momentarily releasing the pad pressure on the rotor. Also to note, the brake releasing does not seem to happen at high speeds, only when at driveway speeds.
Normally when you have to pump the pedal it's bubbles in the fluid, and that may be the case, but the fact that the car seems to coast faster for that moment and the noise goes away makes me think that the pad is actually pulled away from the rotor when the pedal is lightly pressed. Like something is stuck putting pressure on the rotor, but when you touch the pedal, the system starts to work normally and momentarily pulls the pad away from the rotor then back into it. That's how it feels, though I don't understand how the calipers and parking brake mechanism work in enough detail to say if anything like that is even possible.
My plan of attack tomorrow is to get the car on jacks, take off the wheels, and get the engine spinning the hubs and try to look at what happens. Then have someone use the parking brake and normal brakes to see the behavior. Next I would take the pads out and push the rear pistons back into the rotors with my brake tool. (this was done when i replaced the pads and rotors, but maybe I didn't push them back far enough) The next step if that is not successful is to put on some old pads that are very thin and see if the problem still happens. The idea here is that because the pistons self adjust that if the brake off position of the piston is halfway extended, that the behavior may be different than with a very thick pad in there and the piston being nearly fully compressed.
So I'm trying to understand everything I can about the parking brake mechanism and if the going in reverse with the brake on could have caused something to happen. Any information would be appreciated.