Hey guys and gals... My '70 Charger has 4 wheel disc brakes and and power assist. The front calipers have a 2.75" single piston, the rears have a 1.5" single piston. The Booster and master cylinder are stock for a 1975 Dart with a 15/16" master cylinder. Yeah, it is a disc/drum master cylinder but it works great. I do have a drum/drum distribution block, NOT a proportioning valve. This setup may sound odd, but the brakes are great. I want to convert to a manual master cylinder for simplicity, weight savings (15 lbs!) and to be able to use a threaded-adjustable pushrod to tailor the pedal height to my liking. In 2012, I wanted to see how the car would perform with manual brakes. I tried 4 different manual master cylinders with sizes between 15/16" and 1 1/8". Each one resulted in a firm pedal but terrible braking. The best of the 4 was just barely able to skid on a dirt surface. I found later that all along, I had a disc/drum proportioning valve in the system. The power booster must have masked the mismatch. I gave up on the manual brake idea and put the power stuff back on. Now I am considering a "do-over" with the manual brake setup. I do not want to take a step backward in terms of braking feel or performance. I have dealt with Dr Diff before and have had good results. Does anyone here have a 4 wheel disc setup with a manual master cylinder in place? Anyone here have experience with this?