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OK,

New brake hose, same problems, not surprising. But... I started thinking about the events that unfolded to get me to this point, and I came up with a hypothesis:

The twisted brake hose was acting like a one way valve not allowing brake fluid to flow back to the master the way it was supposed to. This forced me to "release" fluid from one of the wheel cylinders to get the drum back on. After I had finished inspecting the linings, un-twistising the hose, and getting everything back together, I bled the brakes. This pushed all of that nasty, brown, water filled fluid out.

Now... As O_D says, water is more dense than brake fluid. Since my master cylinder is angled downwards, water would have settled towards the end that feeds my rear brakes. I didn't take my master cylinder apart when I cleaned it, so who knows what the bore could look like further down. Possibly something like my old rear wheel cylinders (rusty/pitted).

If water rich brake fluid is more dense, then there would be a better seal with that as opposed to say clean brake fluid. Correct? That's why with the old fluid my pedal was firm and the brakes seemed to work fine, and with the new fluid the pedal is soft. Does this sound like a reasonable cause to my problems?

Thank you,

Assembly looks aok. But I do notice that the handbrake lever is already rather far forward. I doubt that the shoes are sitting on the anchor pin, and they MUST when at rest. So unhook the brake cables at the equalizer and shove them back into their sheaths. Then adjust the starwheel as normal (tighten til you can't turn the drum by hand. You should not be able to rock the drum if the shoes are sitting on the anchor pin. If the drum rocks, then the e-brake cables are still holding the shoes off the anchor. Then back off the starwheel till the shoes just whiffle against the drum.) Then adjust the e-brake.

By the way, if it takes more than say 15 clicks to get the shoes from full lock to whiffling the drum, then you need to do the major adjustment. Let us know.

By the way, did you notice the diameter of the master cylinder while you had it apart?

Here is a test for you to try. Go around the car and crank up all the starwheels as tight as you can, ie, brakes locked. How much pedal travel now? Should be virtually none. If there still is lots of travel, you have air someplace--or (it just occurred to me) the front piston set in your dual master cylinder has stuck forward and is not returning.

Another interesting test for that would be to have a buddy press lightly on the brakes while the car is jacked up and go around and try to spin each wheel.

If water rich brake fluid is more dense, then there would be a better seal with that as opposed to say clean brake fluid. Correct? That's why with the old fluid my pedal was firm and the brakes seemed to work fine, and with the new fluid the pedal is soft. Does this sound like a reasonable cause to my problems?

I'd think that's way beyond the realm of possibility. First of all, brake fluid is never "water rich", at most the amount of water it can absorb is extremely small, almost infinitesimal and I doubt it's significantly more dense that dry brake fluid; after the limit of water absorption has been reached, additional water collects as a separate layer and that (the water) is what's more dense and is what settles to the lowest parts of the system. Fluids are essentially incompressible so whether water or brake fluid or a combination of both are in the system, that's not going to explain a soft pedal.

I'd follow Ross' suggestions after you replace all the rusted components.

Howdy there,

It's been awhile since I've gotten to go out and work on my car. Inclement weather among other things kept me from getting this brake issue diagnosed further. Just went out today and did as you said Ross, cranked all the star wheels till the drums wouldn't budge and gave the brake pedal a try. Unfortunately the pedal still travels too much. A couple of days ago I had a helper push in on the brake pedal so I could check the rear drums. It took pushing all the way in with both feet to get the rear drums to the point that I couldn't move them by hand.

Quote:

The bore, as listed on mpbrakes site, is 1" inch.

Hey Guys!

I finally got my brakes working pretty well. I did a "bench bleed" of my master cylinder, but with it on the car. Hooked up a couple of plastic hoses from the outlets into the reservoir and pumped the brakes many many times. I also received help from my brother when it came time to bleed my brakes. Let's just say his legs are a lot stronger than my Mom's. I don't think my Mom was able to push the full travel of the pedal and that was probably a large factor.

Something I noticed is that the pedal feels much easier to push in than it used to. I guess that could have been a result of the twisted brake hose. Anyways, It's great to have my car back, she's so much fun to drive!

Thank y'all for your help; it is much appreciated,

Good to hear it's resolved. For some reason, the bench bleeding seems to be needed and is a PIA on that cylinder. I can imagine how hard and long it took while in the car. Maybe the thing is designed for a horizontal application rather than the angle we use. My cylinder was out and able to be turned every which way to get the air at the right spot to exit but still took awhile.

Thanks for coming back and letting us know the results.

one other thing that causes a low brake pedal is the residual valve leaking back, its a small check valve in the end of the master cylinder, that keeps around 10 psi in the brake lines all the times.