Bad brakes
 

I changed EVERYthing , I got no brakes till one pump , then full pedal . I have taken distribution box apart , cleaned looks good . I think there is a proportion vowel screwed up . Took it off , blew through both ends . You are not suppose to be able to blow through only one end correct ? Maybe thats bad . Ok I pump brakes once full pedel, hit line lock , release pedel , then release line lock . ALL brake fluid blows out ,every drop from master cylinder . Does not proportion vowel suppose to equal to back and front brakes ? I think only around 3 pounds of pressure comes through proportion vowel . Way it looks all fluid blows out . Maybe that screwed up . :cry:

Have you bled all the brakes to make sure all the air is out of them?? It could be something simple as that. Does it have disk up front and drum in the rear or both disk or both drum? I believe that the front brakes apply more pressure than the rear does.

where did all the brake fluid blow out from? air is probably your culprit have you tried just "gravity bleeding" the system? its slow but does get all the air out...

Yes I let the lines drain all day checking and rerfilling the mc . It is a nhra legal car so everything about the brakes have been changed . I even pulled a vacum on all lines . I think it has something to do with a pressure vowl from the distribution box . Some master cylinders have inside something to slow down the pressure to keep fluid from backing back out of the lines when one releases the pedal , like 3 pounds of release . I am thinking that switch is bad for releasing the pedal shoots all fluid out of the master cylinder with the lid off . It is the front brakes fluid cavity that blows dry instant .

Mustang has drum in rear , disc in front . Car had brakes till it sat up all winter . I ran it no problem . No air , I pulled a vacum on all lines . Got full pedal after one pump , release , wait 5 seconds , pedal goes to floor . Gota be a pressure thing in the lines I am hoping.

if its got power brakes that one way vaccuum valve normally on booster may be shot also the proportioning valve may be shot best bet is use after market adjustable one so you can fine tune the bias and not to bee a smart azz not all stangs of the 60's where disc/drum set up some where drum/drum

If it has drum brakes you MUST have a residual valve either in the master or the distribution block or the line itself...somewhere. It keeps the springs on drum brakes from forcing fluid back to the master cylinder. When they are absent the symptom is just like you described.No brakes until you pump it.

Well after typing that I read your post that says it has disc up front. :oops:

I think I will put the master cylinder it had back on it . Thats only think I have changed major . Calibers on front and cylinders on rear should not cause that just because they are new . My guess the old mc has inside a value and 4 new ones does not for they were rebuilt :? :? or sitting made valve in line to go bad . Donot think line lock has a factor .Maybe it is cause I am a home builder and swing a hammer work on cars as a hobby . Too dumb to fix brakes

All R code cars came with a booster and disc brakes in front , however I removed the booster and put manual brakes on . A roller motor needed the room for valve covers and get rid of weight also . Every bit goes faster .

You can buy inline residual valves cheap. I'd try that. I bet that is the problem.