Brakes: Master cylinder push rod adjustment

[tim333]

63 R2 Hawk, hydrovac, front discs, reservoir on firewall, master under floor: what is the proper setting of the master cylinder push rod? Thanks

[warrlaw1]

If the master is under the floor, you need to leave some play in it, so it will release pressure. No experience with hydrovac, but keep your leather lubed?

[64V-K7]

The actuator rod under the floor only needs to be a tad loose when the pedal is full up, maybe 1/16". You can pull the rubber dust boot off and see the piston move when the pedal is pressed. After the pedal is full up, as long as the MC piston returns to a full stop and the actuator rod is loose, then you're fine.

[nvonada]

On my '41 service manual it says 1/4" to 3/8" of pedal travel "before the power stroke starts" I used to think that meant before the piston moves but now I suspect it means before the M/C starts developing pressure.

[64V-K7]

1/4" to 3/8" of pedal travel

This is describing pedal free play..The translation of free play at the pedal to movement at the actuator is significant. Since the pedal motion goes through the pivot at probably a 7:1 ratio, the pedal may move 3/8", but the actuator only moves about 1/16 or less