1971 K20 4x4 brake problem need advice!

[derick1]

Finally got my 71 K20!!!! but need some help. The passenger side from caliper was frozen, so I replaced calipers, pads, an rotors on oth sides. That problem was solved. When I stop it stop evenly on both sides but just really suck. Pedal is hard to push and still seems like the stopping power is not there. Was thinking its the power booster, master cylinder, or maybe rear beaks? I was leaning to the rear breaks but Im not sure any Ideas?

[1972RedNeck]

Check the booster. Step on the pedal 3 or 4 time with the motor off. Hold the brake pedal down and start the truck. If the pedal drops a little the booster is good. If nothing happens the booster is shot.

[derick1]

I just did the test for the power booster, it moved when I started it? Master cylinder or rear brakes?

Is there a way to tell if the master cylinder is bad?

[D.PASSMORE]

Check the rear drums/shoes for drag. The drums should be fairly hard to pull off when removing.

[Metalspatter]

My K20 started requiring a lot of pedal power to stop and it turned out to be a bad proportioning valve. I replaced it because it was leaking and both problems were solved.

[derick1]

I think Im going to change the power booster, master cylinder, prpporting valve, and do the rear brakes. They all look like crap and the truck has been sitting since may. The previous owner was a F&%#. I am planing on just getting it everything tip top but leave the body rough for now. I want to get the chasis and all that stuff looking good an working good or safely!