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No fluid to the rear brakes

68stang289

68stang289

Member
70 Mustang that was factory drum/drum. I did the switch to factory 70 front discs and installed a Wilwood or Baer (I forget which off hand) proportioning valve. When bleeding the brakes I have fluid to the front discs, but I don't have fluid to the rear drums. I have tried adjusting the prop valve, but still no rear drums fluid when you attempt to bleed them. The pedal is pretty hard to press down. Any thoughts on what might be causing the issue and/or how to fix it?
 
"Horseplay" said:
I would start by verifying I had the prop valve plumbed correctly.
Click to expand...

Prop valve is plumbed in on the rear brake line, after the line leaves the factory distribution block. Factory distribution block is plumbed just as original.
 
Depending on what you have you may have it plumbed wrong. Can you give a make/model/part number on the valve? Pics of the install?
 
I think I would start at one of the rear wheel cylinders and work your way to the MC, crack each line until you find fluid to help eliminate things, probably a blockage somewhere. I guess if there is no fluid on either rear, you could start at the brake hose that connects the lines on the rear end.

Or...Start at the MC, make sure fluid is leaving the MC, entering the distribution block, then leaving the block.
 
We verified the plumbing of it was correct. When I bleed the driver's side front disc, I can bleed it like normal (pump 3x, hold, release bleeder screw, pedal goes to the floor). When I bleed the passenger's side front disc and rears, I can't bleed it like normal. I pump 3x (there's a joke somewhere in there :censored ), hold the pedal down, release the bleeder screw, and the pedal goes nowhere and we're not getting fluid out.

I have read that there is a little piston inside the distribution block that will pop sometimes and prevent the full fluid flow. Anyone ever encountered that? My next step will probably be to break the lines from the master and try re-bleeding the master. I just really think based on the normal bleed on only one wheel that the issue is in the distribution block.
 
I would start by breaking the line at the factory distribution block to see if fluid is going through the block since you can't bleed one front side and either rear before rebleeding the master.
 
My 69 with drum/drum brakes had a similar problem with the rears. It was the valve in the distribution block. It was frozen in a position to block the rear lines. Had to disassemble it to free it and reset it. I don't think the valve can block one front and rear though. As others suggested, start cracking the line and see where the blockage is. Have someone apply brake pressure while you go around cracking the line.


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Turns out there were multiple problems. Like RyanG85's issue, we also had the valve not centered in the distribution block. We were able to get that squared away, but still no fluid to the rears. I finally convinced my dad to go down the connections until we didn't get any fluid. Once we did that we figured out that the rubber rear brake line hose was clogged up. We pulled it, capped the line and tried blowing through it and couldn't. That would explain why we weren't getting any fluid to the rear brakes. Thankfully I waited on placing my latest parts order so I can order a new one today and have the rear brake system squared away come beginning of next week.

The fronts are another story though. Driver's side disc I can bleed like normal. Passenger's side I'm not getting fluid out of it. I traced the line cracking it all the way until where the hard line goes into the front braided stainless line I installed. We have fluid to that point, but none coming out of the caliper. I'm going to pull the passenger's side braided line later this evening and see if I have fluid going into the caliper. If I do, I'm assuming something is bad in the caliper? Maybe crud in there somewhere?
 
Replace those rubber hoses with braided SS lines. Shaun at SorT can hook you up with the right parts. If those rubber hoses are originals, failure could come at any time.
 
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