I ordered a master cylinder for a 77 dentside for my 68 because all my donor parts including pre-bent lines came from a 77. I ordered one for std brakes because I gave up trying to source a booster (got totally confused what would work and lacked a donor). Well, since ordering the master cylinder I found a booster set up I can use (I'll do a separate post with pics soon). My question is, can I use the std brake master on this booster. I did some research on line sourcing master cylinders and it appears both pwr and std units are 1" bore, same port sizes and same say push rod depth is 1.46, some say 1.36. I can't seem to find any significant difference. Could the only difference be that the standard brake unit would come with a push rod and the pwr unit not? <!-- / message -->

 

Months back someone else asked and tried as I recall. Orich will prolly remember better. I think the back of the M.C. is the difference. Standard master has an outie (pushrod) where as a power M.C. has an innie.

 

I know the push rod is removable though so I'm hoping everything else is the same. Time will tell when all my parts arrive I guess.

 

The pushrod comes separate in the box with the MC, so as long as the seat of the bore is rounded it should be fine. The pushrod nub in the booster is adjustable so as long as it is set properly the depth shouldn't be an issue either.

 

A manual brake MC will come with an input rod. The input rod has a machined groove near the tip and a clip that slips into the groove of the pushrod. When the manual brake MC pushrod is inserted into the back of the MC, the clip locks into a groove in the primary piston so that the input rod cannot fall out.

On a power brake setup, the booster has its own output rod. A power brake MC doesn't come with an input rod. The power brake MC will not have a receiver groove in the back of the primary piston for an input rod to lock into.

Most, but not all, Ford vacuum boosters have adjustable output rods. All the older Ford truck boosters I've seen have adjustable output rods but I have seen some boosters from Ford cars (some Fox chassis vehicles) that didn't have adjustable booster output rods.

If you have a booster and it has an adjustable tip on the output rod, there should be .005"-.010" clearance between the tip of the boosters output rod to the bottom of the piston bore (on the back of the MC).

Here is a detailed description of how to adjust the booster rod depth into the back of the MC, for any given MC being bolted to the booster.

http://www.maximummotorsports.com/as.../MMBAK-1r1.pdf