1965 Valiant disc brake upgrade

Make sure to use the push rod retainer (little rubber grommet). There's a relief inside the master cylinder slot that the retainer fits into.

When I upgraded mine I put the retainer in the master cylinder slot first, then when I inserted the push rod into the master cylinder, it snapped into place on the pushrod. It keeps the push rod from coming out of the master cylinder.

The adjustable push rod from Doctor Diff has the slot for the retainer and I think he even gives a new retainer with the push rod.

Keep us updated on your progress! Nothing wrong with calling in a mechanic to help! Especially since you're in an apartment at the time.