has inline proportioning valve ,i get pressure to all wheels when i manual bleed, i can feel the shoes move,but i have to pump pedal three times to get a mediocre pedal,like having air in the lines only worse, or way out of adjustment
thats what i think the problem is ,im not moving enough fluid.what master would you recommend using bbp rotors ,calipers from a volare .maual brakes no power
Not moving enough fluid is HIGHLY unlikely;
certainly NOT a problem in the calipers, because when correctly installed, the pistons only move a few thousands of an inch. That means even if they are 2.5" in diameter, the amount of fluid needed to travel .004 inch is about .64cc, for the pair!
At the back , in a 7/8" bore, a quarter inch of w/c travel is 2.5cc; so two of them is 5cc, which is .3 cubic inch. (edited)
This mismatch is why you have to plumb the M/C back to front with the rearmost chamber plumbed to the front brakes, see picture below, You will see how the rear piston is able to slide by the discharge port, until the front piston locks up or bottoms out as the case may be; this is the fluid BETWEEN the pistons.
Now before we get started,here are some tips;
1) your front brakes should be plumbed to the rearmost reservoir, which should be larger than the frontmost chamber. Only because the discs do most of the braking, and the pads will wear faster.
2) The discharge port going to the discs should NOT have any residual valve in it. The port going to the rear brakes COULD have a residual valve, but does not have to have it, unless the w/c's are ancient.
3) The Combination valve should NOT be able to pass fluid from one side to the other; that is to say, the front system is completely isolated from the rear. Your MOPAR C-valve has 5 outlets. This device is actually 3 devices in one housing. The top half is just a line-splitter for the front system; fluid goes in on the end and splits to each side of the car. On the rear half, the line enters on the side and exits out the P-valve going to the rear. If the device has an electrical switch on it, then there is a sealed metal rod between the two halves, that only moves when one side has a catastrophic loss of fluid. It's job is to shut off fluid supply to the leaking side. This is important to know, because; if you don't have the switch hooked up to a light, then you have no idea, if it is centered or not. If it is not centered, it will shut off the fluid-supply to one end of the car. So your first job is to center that valve. It is not spring-loaded, but it is a very tight fit in it's bore. Without taking it apart, the only way to move it, is with hydraulic pressure.
If you are getting BOTH caliper action AND brake-shoe action, at high hydraulic pedal-pressure, chances are that the valve is centered at least close enough to work. ....... for now.
4) the Compensating ports MUST be open when the pedal is properly parked. Shine a light into the larger reservoir and gently stroke the pedal looking for the shiny metal to pass by the hole. STOP! put the cover on BEFORE you return the pedal; If you don't, and if there is air in the system, you could get a brake-fluid geyser under the hood, which requires immediate clean up, to prevent the paint from melting. I wrote that ALL in one sentence, so if this happens to you, I don't want to hear about it, lol.
5) At the back, you have to adjust the shoes all the way out to the drums, fairly hard, then back off a few clicks, spin the tires and repeat. This is done to center the shoes and not get a false reading.
6) If you have new shoes back there, in old drums;
The radius of the drums will not match the radius of the shoes. That means, that the shoes will only touch in a small patch in the centers. This will change as the drums drag the shoes around, but they will not have any effective braking action for hundreds and hundreds of applications.
So In this case, for testing purposes, drive the shoes out to the drums hard! Now go check your pedal with the car NOT moving. ALL tests will be with the car not moving.
If you have a lotta travel on the first pump; something is wrong in the front system.
If the pedal is not rock-hard, something is wrong. You could have air in the line, or you could have a mechanical problem.
To find out which it is;
7) Remove the calipers and Clamp the pistons into the bores so they cannot move. Then check the pedal. It better be Hard, and High, cuz with the rear shoes jammed into the drums, NOTHING is supposed to be able to move.
Now hold the pedal down with a good amount of force, then fix the pedal in that position. It better not move! If it gradually sinks, and you cannot find an external leak, then the only possible explanation is that the M/C is bypassing fluid internally, and sending it back into the reservoirs.
With the calipers and the the w/cs locked from moving, NO fluid can move out of the M/C. That means you can check for air in the system real simple. If the pedal is spongy, either; 1) you got air. or 2) your hoses are soft. or 3)you may have a cracked, warped, or belled drum. If you run out of ideas, disassemble the rear brakes and clamp the w/c's into their bores, like the fronts, and retest. While it's apart, fit the shoes into the drums and see how poorly the radius's match; you may want to get new unmachined drums or get your shoes ground to fit your used drums. Either method is acceptable for rear brakes. But if the pedal is hard, then yur done looking for air, and move on.
Now, I know this is extra work, but you can keep chasing your tail, and keep throwing parts at it, and before you know it, the summer will be over. and you may still be none the wiser. So just do what I suggest, please.
8) If it should turn out that the hydraulics are fine, then we are one step closer to the solution.
take a look at this pic.
Suppose your rear shoes are so far out of adjustment, that the front piston is very nearly bottomed in the cylinder.
And suppose that something is also wrong in the front system so that piston #1 has traveled beyond the discharge port. In this case, the front brakes cannot work, and the rear brakes will be doing all the stopping. The pedal, will be very low. And if your rear shoes are not matched to the rear drums, you are in a dangerous situation.
here is a pic of the Mopar Combination valve; on the right is the front brake side. on the left, you can see Proportioning section hanging off,
and how to plumb it; switch up, and P-section to the rear of the car. On the back you can see the metering block attached which your car will not need.
Here is a cutaway of a generic valve, to show you the guts. This is Not a Mopar but you get the idea.
