I put thread out for future reference. My 52' 4400 received a total over haul on the brakes including replacement of all wheel cylinders, a new dual 1 1/4" master and a 7" universal dual diaphram booster, and a rear adjustable proportional valve. The brakes never felt that they stopped the truck right. I played with shoe adjustment and bleed them multiply times. I always had double pump them and no matter how hard I stomped the pedal, I could not lock the brakes. I took a page from another project and pulled the plumbed master off the booster. There is a little adjustable nipple that inserts in the back of the master piston. I turned the nipple out a 1/4" and reassembled.The first attempt put me through the windshield, with a tap of the brake. the third adjustment screwed back in a 1/4 turn and the brakes stop without locking, and with a little tweaking the proportional valve, stopped like today's drum brake vehicles. I hope someone down the road uses this to plan and execute a brake project from single manual to a power dual master.
