sounds like air in the lines to me. bleed the brakes and recheck. also pump the brakes and hold the peddle down. if the peddle starts to drift down its got a bad master cylinder. if the brake peddle is firm and does not drift down its one of a few things. you have a caliper hanging up so the pads are not applying pressure to the rotor a pinched hard line or swollen rubber line or a bad booster. the best way to go about it is to removed the tires and have someone press on the peddle watch to make sure that the pads are moving and the rear shoes grab. also check to make sure that you didnt have a spring on the rear drums break. if that were to happen you would only be getting front brakes and this would make it hard to stop. if you can give me somemore info i can help you somemore.
