Dual chamber master cylinder for drum brakes

[V8 Bob]

Originally Posted by KULTULZ

SOURCE - https://www.sundevilauto.com/what-do...for-my-brakes/

While most of the above info on proportioning valves is correct, the actual operation is not. Fluid is never "blocked", but is delivered based on the percentage value of the valve once the "crack point" pressure is exceeded.


As for drum brakes, some proportioning could have preceded disc brakes if the earlier D.O.T. brake performance requirements had been much stricter, like those starting in the mid '70s.


A good example of the possible need for a drum prop valve is when using late duo-servo rear drum brakes with obsolete non-servo front drums, something done often with old (pre-'49) Fords.