Component sizing help!
A.) I don't think you really mean "dual piston" m/c. What you have is a dual reservoir / dual outlet master cylinder. Sometimes called "tandem" master cylinders. It has two fluid output ports, one for the front and one for the rear. There is only one piston inside, acting upon two chambers.
B.) As to sizing, I went by what the manufacturer recommended, which for my car/brakes was 15/16". I'm sure there is some theory or calculation involved to determine the correct size. But bigger isn't necessarily better.
Dual reservoir / dual outlet master cylinders:
A.) I don't think you really mean "dual piston" m/c. What you have is a dual reservoir / dual outlet master cylinder. Sometimes called "tandem" master cylinders. It has two fluid output ports, one for the front and one for the rear. There is only one piston inside, acting upon two chambers.
B.) As to sizing, I went by what the manufacturer recommended, which for my car/brakes was 15/16". I'm sure there is some theory or calculation involved to determine the correct size. But bigger isn't necessarily better.
Dual reservoir / dual outlet master cylinders:
