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