65 & Brakes

[G65Bird]

Hey kinda new to this site. I own a 65 with a 390 in it. Has discs up front and drums in the back. Ok heres my problem i had a leak in the brake line so i replaced it. After that the pedal went to the floor so i thought i had some air in the lines, but i have bleed all the lines numerous times. The pedal still goes to the floor. Replaced the master cylinder, and that didn't help. Yesterday i pushed on the brakes and had my dad try to turn the wheels and well the fronts grip fine but the backs i can turn freely. Checked the drums but seem fine to me. So i was wondering if any of you guys out there could help me, this problem really has me stomped me.
Thanks alot

[Joe Vandatta]

When you bled the brakes did you get fluid to the rears? If so, they must be way out of adjustment since your fronts are okay.
Joe

[Harley Eaton]

There is a proportioning valve in the rear brake system to keep the rear brakes from locking up when you apply. It is located beneath the master cylinder on the rear of the spring/shock tower. Sounds bad!

[G65Bird]

alright thanks a lot i'll check that today