[QUOTE=Kook;780555]Not sure about the residual valve thing. What and where would it be![/QUOTE]
If your rear brakes were ever drum brakes you would have had a residual check valve.
Many master cylinders had them built in to the end of the master cylinder where the line goes in. Some had a nut @the end of the master cylinder where the brake line screws in. Behind the nut was the valve and spring. See this picture for an idea about the valve
[IMG]https://www.freeasestudyguides.com/graphics/residual-check-valve.png?ezimgfmt=rs:556x459/rscb21/ng:webp/ngcb21[/IMG]