1985 Ramcharger 4x4, replaced front pads, master cylinder and power booster. Adjusted rear shoes and checked all rubber brake hoses front and rear. Bled the master cylinder on the bench, bled the complete system after installing the master cylinder. The problem is that the truck will not stop unless you (1) Stand on the brake pedal while pulling down with the steering wheel and (2) Saying the Lords Prayer or screaming obscene words rapidly with your eyes closed. Eventually it will stop. The pedal is hard as a rock. With the tires off the ground the wheels spin freely and stop when the brakes are applied. they do release when you let off the brake pedal. I replaced the master cylinder first and the problem was still there. Power booster was next and it still won't stop. Any suggestions.

 

Sounds like you are not getting the assist from the booster. Did you check you have good vacuum going to it.

 

I will check again when I get a chance. It had 20" to 22" vacuum last time I checked. The booster is new and states that the warranty is voided if the check valve is removed from it. When you start it up, the brakes feel normal. When moving, they just won't stop the truck. Wet or dry surface and it won't lock up any of the tires.

 

Sounds like it is not holding the vac in the booster. Is the vac line going to the intake manifold port?

 

Vacuum line goes to the manifold. Recently pulled the oem 2bbl carb and manifold and installed 4bbl setup but the brakes were the same with the 2bbl setup. That upgrade was well worth every penny. Summitt 650 carb with an Edelbrock aluminum intake. It runs so much better but won't stop.

 

to test the booster:

-engine off, pump the pedal multiple times to deplete the vacuum reserve
-press and hold the pedal down
-start the engine
a properly functioning booster ....the pedal should be drawn down further as the booster supplies vac assist.

 

I forgot to mention that in the original post. The pedal does drop 1 to 1.5 inches on the above mentioned test.

 

then the booster is working properly.

are the caliper pistons and the wheel cylinders frozen? Can you push the pistons back. palm strike each shoe, you should see the wheel cylinder move.

What are the rotor and drum faces like. If they, are in poor condition, it will created a low co-efficient of friction...similar to applying greased up or wet pads.

 

This vehicle was saved from going to salvage. Upon getting it home, the front pads were replaced due to being wore down but not metal to metal. The rotors were well within specs and smooth. The rear shoes looked great and so did the drums. With the vehicle on jack stands, you can rotate the wheels and then stop them with the brakes. With the trans out of park you can remove the lugnuts with a 4-way while the brakes are applied. All four wheels turn freely (normal) when the brake pedal is released.