Rear Brake Noise

HI guys. I have a question for my 2001 Intrepid SE, 91000 miles, V-6 car. I think my rear drum brakes need a tune up/check. When I drive short distances they make no noise, but when I drive long distances, and I brake, the rear brakes make a grinding/metal on metal noise. It sounds horrible. The thing is, I don't have to dispress my brake pedal all the way to stop, just about half way. I can't remember the last time I changed my rear brakes, but had the front brakes replaced about 2 years ago. I don't want to put more strain on the front brakes and I don't want to wait to long as to cause more damage. Any thoughts would be great. Thank You. :D