Brake Booster Push Rod

Remove master cylinder. Install adjusting gauge on master cylinder with master cylinder gasket in place. Lower adjusting gauge pin until pin slightly touches master cylinder piston. See Fig 1. Turn adjusting gauge upside-down and install on brake booster.
Measure clearance between brake booster push rod and adjusting gauge pin head. See Fig 1. Measured clearance should be zero. If clearance is not zero, adjust brake booster push rod length until push rod lightly touches adjusting gauge pin head.

Fig 1: Adjusting Master Cylinder Push Rod