Brake problems

[LAREDO JOE]

my front brakes were making a popping, grinding noise( left front) so i decided to replace the pads. they were probably a little better than 3/4 worn down. i installed the bendix metallic style pads and cleaned everything up. the previous noises went away but i started getting a high pitched squeaking. the noise changed pitch as i
applied the brake. i took the rotor off & had it "trued" as they call it. not much taken off of it at all. the noise never went away. i bought some softer semi-metallic pads and put those on. now i don't have the squeak but have the same grinding sounds as i started with, maybe worse. what should i do? replace the rotor(warped)? could it be a bad caliper?

[Chevelleguy]

To eliminate "comebacks" due to noise, we only install the Wagner 'Thermoquiet' pads. They work real well.

[azshtr]

I've never had a problem with cheepo pads until last year. The AutoZone cheepies ground like I was loosing a rotor. I actually removed the rear due to my thinking it had to be those as I had just done the front. Then took apart the front to see what fell apart, only to find all a-ok? Took off the cheepie pads and put on top of the line and the diff was unbelievable. I've never had that before! But it was the cheepie pads causing the grinding feeling. Actually the rotors were just fine.