Were the brakes working OK BEFORE the booster and master cylinder were installed?  If so, proceed to next paragraph.

It sounds like the booster output shaft is adjusted too short.  It should be adjusted so it has about 0.010" clearance from the MC piston when installed.  Easiest way to achieve that adjustment is to remove the MC and adjust the rod until the master cylinder will no longer fit flat against the booster. It will "rock" on the excessively long booster pushrod.  Then adjust the rod shorter in very small increments until the master cylinder no longer rocks.  You want that distance to be as close to zero as you can get it.  Allow a tiny bit because the master cylinder will pull towards the booster as the nuts are torqued.

If you did a complete brake rebuild when you also installed the booster, and did not drive the car before you installed the booster, be sure the brake shoes are all adjusted out against the drums.  If you don't, the master cylinder has to push enough fluid through the system to get the shoes out to the drums before it can apply any braking force, and that travel uses up all the capacity of the MC.  If yuo think that might be the case, you need to adjust the brakes.  Even though they are self-adjusting, they must woprk well enough for the car to be driven before they ca adjust themselves every time you apply brakes while backing up.  Tighten the star wheel adjusters until you cannot rotate the wheel by hand, then back off 10 clicks.  If your drums are oversized (worn out) then you may never get there with the adjustment.

The MustangSteve power brake kit is a SYSTEM that must include all the components as designed to make it work.  You cannot mix other boosters with it.  Many people have removed the SSBC and MPB and other systems when they had incurable brake issues, installing the MustangSteve kit to cure the problems. 

Hopefully adjusting the booster output shaft or adjusting the brakes will do the trick for you.

Another possibility, but less likely, is if you have a master cylinder with too small of a piston bore.  That will make for a very long stroke with no braking until you get to the very end.  But it would have to be ALOT smaller than normal to cause that issue with drum brakes.

Last edited by MustangSteve (4/07/2014 3:00 PM)