[Larry Spillman]

If it isnt air or a bad master cyl and you have drum rear brakes you may need a residual valve to keep a small amount of pressure in rear lines this will help brakes work better. Disc brakes work on pressure drum brakes work on pressure and volume it takes more fluid to open a rear cyl than it does to operate a disc caliper.If you have discs front and rear you may be boiling your brake fluid it can be getting to hot which will cause pedal to fade. Good Luck L Spillman