Dual master cylinder change over

[DR.DETROIT]

Just installed a dual master cylinder on my 1964 valiant, I ordered a new master cylinder
that would fit a 1967 valiant. I believe that was the first year they installed dual.
Brakes work ok, you have to push hard, thinking now I should have got one with a
larger piston bore, 1" is what I have. Any thoughts.

 

[emsvitil]

Smaller bore gives you better 'leverage'

A larger bore would make the pedal even harder.

 

[BillGrissom]

If front drums 1" or even 1-1/8" D bore should be fine. For front disks w/ manual MC, most people prefer the smallest bore possible - 7/8"D. A newer aluminum one works w/ a 2-4 bolt adapter plate. Dr. Diff sells one for ~$100 (linked many times). Many here are fine w/ manual MC w/ disk brakes, but for some reason even the smallest cars today come w/ a power booster and even Mopar shipped that for most front disks in the 1960's. With a small bore, it is even more important to get all air bubbles out of the system and insure the brakes hoses aren't soft, otherwise the pedal may hit the floor.