No line pressure to rear disc conversion, no prop valve

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roger0080

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Check the pedal rod adjustment. If is extended to long, it will push the master cylinder pistons past the rear line outlet effectively blocking that port, thus no pressure at the rears. Had this experience once on a used pickup I bought. Had fronts yes, rears no.
 
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sctaylor

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Update:
Disc/ disc Mc & p-valve installed & bled (bench, then pressurized, then vacuum pump). Pedal still soft & zero caliper action front or rear. Next up is rotating the rear calipers (mounting bracket) forward to see if I'm trapping air.
Thx again for the help.
 
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Bennyt

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sctaylor said:
Update:
Disc/ disc Mc & p-valve installed & bled (bench, then pressurized, then vacuum pump). Pedal still soft & zero caliper action front or rear. Next up is rotating the rear calipers (mounting bracket) forward to see if I'm trapping air.
Thx again for the help.
Click to expand...
On my K5, D60/14BFF, I actually mounted my calipers upside down so the p-brake cables went over axle for ground clearance. To bleed, I would remove calipers from bracket and hold upside down with a 2x4 in between to bleed.
 
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sctaylor

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Wound up keeping the position & swapping sides. E brakes are unhooked (ratchet pedal may be toast). Hose now enters caliper below bleeder, which is horizontal but on top. That's the best positioning I can figure out, keeping the calipers above the hub (still a truck). Still gotta bleed more, but finally got some pedal resistance. woo-hoo!
 
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