Please help me with my brakes

I searched the forum have not found out exactly what I need to know so here goes. I have a disc/drum setup on a 63 galaxie wagon that was modified when I bought it. It has a non powered dual master, original rear drums and front discs from the late 70s ford parts pile. I have noticed that sometimes if the car sits for a a couple hours or a couple days when I get in there is no brake pedal, goes right to the floor. I can however pump it for a while and pressure builds up. As I drive the pedal gets firmer and sometimes almost too hard. On two occasions I was unable to build up adequate pressure, or lost pressure. The fluid level is good. Im going to dig into this tomorrow because not stopping is not fun. Im thinking the first thing to do is bleeding, possibly air in the system, but I dont think that would account for the pedal getting hard. After that Im not exactly sure the most logical way to troubleshoot this. Could this be bad master, lack of, or faulty residual pressure valve, no proportioning valve, drums out of adjustment? Any suggestions that point me in the right direction would be greatly appreciated.

Thanks
Al

 

Im no authority on brakes but, . . . . i would first check for leaks throughout the whole system, then check for air, if there are no leaks i would imagine it is your master cylinder.

Are you sure its a M.C for a disc /drum application ?

 

If no visable leaks ,my vote is for a bad M/C.

 

Sounds like classic lack of residule valves. This is if the M/C is under the floor, fluid is draining back into it. The pedal getting harder sounds like the lack of enough free play in the pedal and heating (and expanding) the fluid.

 

Good advice, but it's a '63 Ford, if the MC is under the floor someone needs to find the guy who moved it there and kick him in the groin.

 

The rear drums get a residual valve, too. Chances are the springs are pulling the shoes back and making the wheel cylinders need to be repumped after it sits. I believe you want a 2lb residual valve in the line to the rear brakes, provided that your master if higher than the wheels...

 

since your master cyl in on the firewall. you you need a 10LBS residual valve going to the rear preferably as close tot he master as possibler. but you should also have a proportioning valve for the rear. if you have one of the manual valves then the residual valve needs to go after that. if you have a proportioning valve that acts a distribution block as well, then you dont need a residual valve. personally i would not run the distribution block unless it was designed by the factory for your car.
you say it gets harder and harder. i would be looking at your brakes grabbing when your foot is off the pedal, make sure that there is a little freeply in the pedal before it engages the master.
check for leaks, check for air.
Dave

 

Hello-
I am not an expert but checking the entire system for leaks is a good idea. I have in the past used a master cylinder from a 1968 Mustang with a disc/drum application. The master cylinder I believe contains the check valves that everyone is talking about. The flange is a two bolt style, side by side, differing from the old Ford which is three bolt in a 'Y' pattern. Keep on asking questions, go the oldest mechanic you know, and ask him. Likely, he has been down this road before and could point you in right direction.

 

fixed it for you


as for your problem, replace the master cylinder as it has an internal leak.