no flow to rear brake calipers

[trippbannister]

all right, so i'm having a little trouble brainstorming what could be going on with my rear brakes.

here's what ive done so far on the brakes of my 71 or 73 spider. new master cylinder, new resevoir tank, new tank to cylinder gravity hoses, new front calipers, and cleaning up of the rear calipers.

the new ones up front work great. i bled them and they hold pressure and seem to work fine. the rears, however, won't bleed. this is what i've done to chase the problem from font to back:

loosened the tubing connection at the distribution box before the tube heads back under the transmission tunnel, and fluid came out. i loosened the OUTPUT tube connection on that compensator valve that shuts off when the axle to body distance increases (this valve is frozen open anyway) and it took a few pumps, but fluid came out of the compensator output. that's where it stops. i just can't seem to get it to flow through that last piece of tubing to the right/left splitter and then on to the calipers. i guess my next step is to disconnect the hoses from the caliper and see if i can get some fluid out of the hose when i pump...

hoses look fine, e-brake cable is disconnected (temporarily - but this doesn't affect fluid flow into the caliper, right?), tubing isn't in great shape but it could be worse, calipers are old but should at least fill up with fluid when the bleeder is open. i can't think of any other places it coule be held up, unless there's a clog in the line between the compensator and the splitter. could this happen?

i'm out of ideas for now. what's funny is that i had almost the same problem on another car. it turned out to be an extra bleed screw on the compensator valve. as soon as i bled the air out from this valve, the brakes tightened right up and worked great. i don't see any other fittings on this compensator valve, plus i'm pretty sure i got the air out when i loosened the output tube. is there somewhere else air can get trapped?

i used to think brakes were so simple!!

[So Cal Mark]

I have seen tubes with clogs, but it's always been near an exhaust pipe where the heat eventually coked the fluid. I'd disconnect the tube at both ends and blow compressed air through it

[mdrburchette]

I had a problem bleeding my fronts and found gunk in the lines, stopping the bleeders up.

[pauljdav]

Where are your jack stands? If they are under the frame the brake system will not allow fluid to go to the back brakes. The car must be supported by the axle so the brake system will allow brake fluid to the back. I.E. the suspension must have weight on it.

Also if you just rebuilt or replaced the calipers the notch on the piston that "screws" must face a certain way or the system will not bleed.

Good luck.

Paul

[trippbannister]

alright, thanks for the ideas. i do have the jacks under the rear axle, and i put the notch flat when the pistons were screwed back in. i thought this was the right position to make sure it bleeds, but i'll double check. i'll mess around with it again this afternoon. getting warmer in dc..