Master Cylinder???

DO NOT use your drum/drum MC. The residual pressure valve will cause the disks to drag and overheat. Even if you remove the valve, the drum MC has a much smaller reservoir for the front line, and you may need the capacity of the disk MC.

For a manual disk/drum setup, use the POWER disk brake MC listed for A-bodies. This will have the smaller 15/16" bore and give reasonable pedal effort. If you're feeling macho, you can use the MANUAL disk MC, with a 1-1/32 bore -- this gives a very stiff pedal requiring about, oh, 180-200lbs of foot pressure.

BTW, do not trust the on-line application listings for MCs on Rock Auto or NAPA, etc. They contain a lot of mistakes and misinformation, particularly for cars earlier than 1972. For instance, for a 1967 Barracuda, they will show the drum/drum MC for disk brake applications, if they show a disk brake option at all. So be sure to read the specs -- don't just order based on the application.

mopowers said

I'm going from manual drums to manual discs, so the recess should be the same, right?

After a little research, the bore diameter for a manual drum/drum car looks to be 1", whereas the bore diameter for a manual disc/drum car seems to be 1 1/32". Is that enough of a Difference to worry about??

So, it looks like my only hang up should be the residual valve in the master. Is it bad to run a front disc brake system with a master with a residual valve?

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