System... 39-48 drums on all 4 corners. 67 Mustang drum/drum dual master cylinder. Question 1: Front drums connect to port closest to pushrod? Question 2: Will a residual pressure valve be needed on front or rear or not at all? Thanks, Marty.
10 pound residuals, front and rear, and on drum drum it really doesn't matter which part of the MC the lines go to, but part closest to pushrod normally goes to front brakes.
Discovered my master cylinder has built-in residual valves, so I'm good to go. Read about the test using a small drill bit, and sure enough, felt the rubber valves.
BUT you moved a firewall mount to under the floor,so you need to add the residuals to compensate for that. Gravity USED to do that job.
You poke around in the outlet ports and feel for the built in residual valve. I use an allen wrench myself but about anything that you can poke around in there with will work.
It really does matter which port goes to the fronts on drum/drum masters, because most are not 50/50 in volume output, as the front wheel cylinders are always larger and require more fluid. That's the reason the outlet ports are different sizes, so the front/rear lines cannot be switched during replacement/service. If you do not know how the master should be plumbed, don't use it, period. Plumbed incorrectly can likely result in a displacement problem.
I've got the 67 Mustang master cylinder setup under the floor on my 48. I needed to add the residual pressure valves to both to get a good pedal. I don't know if it has the built in valves, but I had to pump the brakes a couple times before I added them. J.
whether if the mater cylinder has built in residual valves or not , you can still add them inline.....it will not hurt to have two http://ecihotrodbrakes.com/brake_facts.html
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