I need some brake suggestions

Hey Guys,
Ive got a strange problem I thought I fixed but is now comming back on my brakes. first off, 1950 Caddie 62 series with original brakes. I have gone through master cylinder and all wheel cylinders. Relined the pads and cleaned the hell out of the springs, etc.. I believe I flushed all the crap out of the hardlines and I did replace the hoses. Ok, now for the problem. On long drives say 2-3 hours or so, I can feal the brake pedal getting harder and I begin to lose power. You guessed it, the brakes begin to lock up, but its just usually one wheel. Ill get under it, bleed off a little pressure, and good for a little while. Once this happens, its not long before it happens again. Another observation is that when things are cooled down, I dont have the problem. This is a real pain in the ass. Im wondering if it could be a minor adjustment or heat from my headers heating up the master. Any suggestions would be appreciated.
Fred

 

is there free play at the brake pedal?

 

yes there is, but when the problem starts to happen it slowly disappears until there is none. This is the time the brakes are locking up.

 

Is there mechanical free play? the pedal should move a little bit before it starts to push the master cylinder. This could be the problem....if the m/c is pushed in a little bit all the time, then it will have the hole blocked that is supposed to let the fluid back into the reservoir as the fluid expands from heat.

 

Hey Squirrel, Thats some good info, im wondering now If possibly the return spring in the m/c is a little week. I do have play in the pedal linkage but the spring in the m/c could be week covering the hole. What do you think??
Fred

 

yeah, if the spring is missing or weak then the pedal could be pushing in the m/c a little bit just by it's own weight.

 

Thanks Squirrel for all the suggestions.
Fred

 

Did you replace the flex lines? They are notorius for deteriorating on the inside and letting high pressure through but not the low press return created by the springs. The trapped fluid boils and locks up a wheel or more. Hpoe this fixes it. Jerry

 

Thanks Jerry, I am now fully loaded with all kinds of new ways to approach this problem. Thanks everyone for the help. Ill get back with you and let you know what I find.