1963 T Bird. I replaced front brakes with disc conversion kit plus added a new master cylinder and a proportioning valve but brakes won't release, any suggestions
So it could be a stuck proportioning valve or the shaft is too long going into the master cylinder, it maybe adjustable but you will have to disconnect it from the brake pedal and remove it to find out.
There is a possibility your engine is running hot & expanding the pressure on fluid in master cylinder.It will not lock up if engine is cold.
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