early 60s disc brake swap master cylinder

[theastronaut]

Originally Posted by PM Garage

Yup, you can run discs with the stock MC, but don’t expect great pedal feel. Did it on my ‘63 C10 for a while. Braking worked, but it was real soft and kinda sketchy under load. If you’re not adding a booster or proportioning valve, just be ready for uneven braking until you upgrade later

The stock drum brake master cylinder has a residual valve so it shouldn't be used with discs without removing or disabling the internal residual valve. The calipers will drag if its no removed.