Front Brakes Hardly Working

Thanks everyone. So its the Kelsey Hayes 4 pistons Ive had the car for a while and I just thought the brakes sucked but an older mechanic aligned it for me and told me they weren't right. I have a hard pedal, when I bleed it goes to the floor, plenty of fluid coming out. It has enough pressure to stop me from spinning the wheel but when I go down the driveway and apply the brakes hard the back wheels lock up and I skid down the driveway as though the fronts aren't even working. I was gonna use a spacer to see if the pistons moved under pressure, I know they don't travel much but I should see some movement I think. I have purchased seal kits for them but new calipers are $150 a piece, I just don't want to throw money at it.