1981 Firebird brakes

[firebirdman81]

I have an 81 Firebird that has been parked since 1996. Before it was parked, the brakes worked great, just touching them they would react. I brought this car out again in 2008 and some work needed to be done from sitting so long and the only thing I can't figure out is the spongy brakes. Before parked the calipers and wheel cylinders were replaced along with return springs and just last year a brand new master brake cylinder.

Still spongy brakes even though the brakes have been bled over and over and the rear shoes adjusted tight. One thing a friend of mine had noticed is the sliders on the calipers looked very dirty. Would this be the cause of spongy brakes?

[maxwedge]

The sliders would make to brakes ineffective and prevent the caliper from moving, I would focus on spongy flex hoses, master cyl. bypassing, rusty rotors and drums.