I just repaired a "sticking caliper", by replacing the rubber hose. They can go look OK on the outside, but get a crimp on the inside and only allow fluid to pass in one direction. One way that you can check is to open the bleeder screw on the suspect caliper and see if it releases and allows the rotor to spin freer. This would mean that the pressure is still being applied in the lines even though the pedal has been released.
On your other posts, you had spoke of changing your race car from dual master cylinders to a single one with dual outlets and of having drum brakes on the rear. Your hard pedal could be due to other problems, which could be the mechanical ratio or too small a master cylinder bore. Here is a link to an article on brakes, bias, and pedal ratios.
http://www.hotrodheaven.com/tech/bra...kes1_index.htm
Master cylinders have different bias ratios and bore sizes depending on what application they are to be used on. Also, the front port on a lot of master cylinders goes to the rear brakes because of the bias. I am thinking that the Mopar one that I have is a 69%/31% split.
For the ratio, you want to be around 6:1, this is determined by the length of your pedal from the point of pivot and the distance down to where you connected the master cylinder rod at. If your pedal is 12" long from the pivot point and the rod is connected at 2" down from the pivot, then this is a 6:1 ratio. But, if the rod is connected at 3" down (usually the spot where the power brake rod connected) then your ratio would only be 4:1 and have a much harder pedal.
Be safe on this and get some help if you need it. You need for this to be correct and there is a lot more to it than just bolting on pieces.
Bill M