Brake Master Cylinder Valves

Why would you remove the residual valve from the rear drum brake portion if the car still has rear drum brakes?

I can see removing it from the reservoir that serves the front brakes if you are trying to use a drum/drum m/c on a car that will have disk/drum.

...or you can buy a new/reman m/c that is for a factory manual disk/drum car at rockauto for $50.


We need to know-

A are you planning for power or manual brakes?
B are you planning on keeping the rear drums? (rear disks are a whole different ball game)
C did the m/c you are asking about using come from a car with manual or power disk/drum or drum/drum brakes?


...and if you can, get the valve from the car you got the m/c from, if it is a disk brake car.

many Mopars after 1972-ish used the "Texas" shaped valve that includes the prop valve.
I believe these are all the same and can be had cheap at most salvage yards.
Look on M bodies, and even trucks up into the 90's.
The only potential issue is plumbing, as it will likely want the lines to be in different places than what was on your car originally.