The booster input and output rods are separate but are attached, internally, inside the booster. They shouldn't just slide out of the booster housing. The output rod, not the input rod, determines the engagement length to the MC. There should be .005"-.010" inches clearance between the tip of the output rod to the primary MC piston, with the brake pedal in the static position (brake pedal NOT being applied).

I don't know what booster you have or, if it has a threaded input rod eyelet that's adjustable in length (?).

This is a single diaphragm booster from a '68 F250 that I have. It has an adjustable input rod and of course an adjustable output rod to the MC. The adjustability in the booster input rod only sets the height of the foot pad on the brake pedal, in relative distance of the foot pad away from the floor. Shortening or lengthening of the booster input rod doesn't alter the pedal ratio. The only way to alter the pedal ratio is to increase the distance between the brake pedal pin and the brake pedal fulcrum pivot.




This is a '74 F350 dual diaphragm booster I have that's very similar the the '75 F350 dual diaphragm booster that's on my truck. --only difference is the added plate across the face where the MC bolts up and the extra plate that wraps around the back side of the booster housing.





The output rod to the MC is adjustable.




....the input rod is a fixed length (non-adjustable), just like on my '75 F350 booster.




I didn't change or alter the input rod on my '75 F350 booster. It just connected directly to the pin my my '69 F100's brake pedal.

This is the method I used to adjust the booster output rod depth to the '95 Explorer MC.

http://api.viglink.com/api/click?for...FMMBAK-1r1.pdf