Noisy rear brakes, I think?

[wjwncpro]

2000 Exp. XLS 4.0
I was hearing the "bird chirp" (although more constant then a chirp) noise at my rear brake area. I replaced the rotors last June (felt like they were warped) and I recently repaced the pads even though the old pads still had half life left. I am still hearing the noise mostly below 30 mph and fairly constant (not quite chirpping but high piched, not loud but noticeable) and has the rotating sound as if it is coming from the wheel (as you speed up and slow down).
Any ideas...
Thanks

Ps; The noise is more prominent when the brakes are applied.

 

[slapthefunkyfou]

I know this answer sounds funny, but my brother's truck had that same problem. It turns out it was his hubcaps. Do you have hubcaps? If so take them off.

 

[wjwncpro]

Their the stock chrome wheels, with caps.