Semi O/T - Brake question

I have this brake problem that keeps me wondering. This question concerns my '91 cutlass sierra, so sorry about the car being O/T, but all cars have brakes, right?

My rear brakes were shot, so I changed my rear drums, wheel cylinders and shoes. I bled them right, but afterwards the pedal traveled almost to the floor before I felt resistance. Needless to say the braking sucked. I looked at the front and the brakes were shot too. So I changed the rotors and pads. The pedal travel is slighly better now, but not by much. I can't feel any air in the system when I pump the brakes. The master cylinder is one year old and I don't have any leaks.

Anyone has any idea on what's happening?

 

Pull up the emergency brake some and see if the pedal gets any better.

If it does, ya' need to adjust the rear brakes up.

When ya' install new rear brakes ya' have to watch the e-brake cable adjustment.

 

Already tried this, no luck! The adjustment is right.

 

Any other idea out there? Since everything else is new, I'm starting to wonder if the one year old master cylinder could have gone wrong...

 

Sometimes, the centering pin in the proportioning valve sticks to one side and will not allow pressure to the rear brakes. Are the rears working at all?

 

The rears are working as good as the fronts, which is poorly...

 

Well, if both ends suck, I'd begin to suspect the master cylinder.