I have an underfloor mounted masterbrakecylinder in my 27 Model T, which is mounted under the level of the wheelbrakecylinders. So I am using 10Psi residual valves for my four drum setup to prevent blake fluid from running back into the MC. Question is, if I still need the residual valves, when I use a remote brake fluid reservoir, mounted at a higher point than the wheel cylinders?
I'll say no based on my VW Bug days. They don't use the pressure valves, the MC set up has the higher mounted reservoir.
Drum brake residuals have nothing to do with master cylinder location; they prevent air from entering past the wheel cylinder cups during brake release. Most/all vintage drum brakes used and needed them, but residuals also will help with pedal feel on later '70s-up drum brakes as well.
Leave them in place. If you take them out you will end up with increased pedal travel and air in the system eventually. To stop you would probably have to pump the pedal up a bunch just to get pressure to the wheels.
Yes sir. exactly this. the residual valves hold pressure in the lines to keep the cups sealed in the wheel cylinders. Most dual drum brake master cylinders have a light check valve behind the seat for the brake line fitting in the master cylinder to hold pressure and the single piston cylinders have a check valve in the end of the cylinder usually set in the spring inside the master cylinder.
You may want to ask if you should remove the check valves in master if you are running C/Vs in the lines? Seems redundant and could cause problems ? I don't know the answer just wanting to throw that out there for some smarter HAMBer to answer. Ralphie
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