The first run of the repoped prop valves were defective and I had the same issue with my 71 Charger RT. The problem is the top piston letting fluid travel one way to the calipers but not back to the master when you release the brakes. You may be able to search my prev post a few years ago about this issue. The simple fix is to replace the upper piston with one from a oem valve. My valve worked perfectly when I did this. I notified some of the suppliers of the defect but I saw many at Carlisle selling the defective valves the same summer.