SSBC disc brakes won't stop

There you go. Now you know the front system is A-OK.
So now lets talk about the rears.
Go back to my previous post. The whole point of that post is to make sure the rear pistons are out against the pads, and that the pads are all in intimate contact with the disc, and that everything is in the correct working relationship. If the caliper is a slider-type, it has to be somewhere in it's normal working range. If it's a fixed caliper,bolted-to-a-bracket with pistons on both sides, then again it has to be well centered and somewhere in its normal working range.It is very important that the pads not be bent, and that they are exactly correctly installed.
-So now, if everything back there is 100%, then it's time to bleed it.
-Now here's something you need to know; It is often very difficult to bleed disc brakes by yourself. This is because with the rear bleeders open,as you push fluid out on the down-stroke, then sometimes, on the pedal return, the fluid also returns. When this happens it is impossible to bleed. To get around this I often have to clamp the rear flex-hose,just enough to offer resistance to the fluid that it cannot return, and crack open only the nearest bleeder to the MC.I use the special bleeder cup with the hose attached, and the tube that runs to the bottom of the cup. Then I can watch as a helper pumps the pedal. When the fluid gets to this side, I pump a few strokes into the cup and close the bleeder. Then I move to the opposite side, and bleed it the same way ,but completely. Then I return to the first side and finish there.
-With a M/C for a drum brake rear system, the M/C usually has a small rear reservoir. So, you have to keep a very close eye on the fluid level. You have to keep it pretty high or the system will suck air on the return stroke. The compensating port will need to be more than just covered, cuz of that. At least 1/2 inch. More is better.
-If you cannot seem to get fluid out to the back, there is a good chance that the compensating port is not working.If this happens to you,give a shout back and I'll walk you thru proving it.
- The M/C that you now have, will work just fine; if A) you remove the R-valves, and B) you forever keep a close eye on the rear fluid level, and C) you don't mind the pedal effort.
-Once the system is working,the big bore M/C should have a hard pedal very early in the pedal stroke. I find this hard to modulate, but lots of guys like this.
-Don't worry too much about the P-valves right now, but run the aftermarket one wide open during this bleeding exercise.Later after the road-test is successful, you can dial in the rear pressure.
-The R-valves maintain about 8 to 12 psi in the line(s). If you do not remove them the piston-seals will not be able to retract the pistons, and the pads will drag. The engine and tranny torque-multiplication will overcome this and you may not notice this. But the rotors will run hot.
-Make absolutely sure that if you have a factory P-valve that it is correctly plumbed.Only the rears should be proportioned, and the amount of proportioning is application specific. The factory set-up was playing it way too safe. They must have been really afraid of law-suits due to premature rear loc-ups sending people into spins.I am running Zero rear proportioning, with Zero problems.
-Oops, I see you say you didn't get the old P-valve. So I guess you still have the safety switch then?
Okay so good luck.