No fluid to rear brakes

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by haroldpo6, Nov 29, 2015.

  1. haroldpo6

    haroldpo6 Veteran Member

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    1970 Camaro getting no fluid or very little to rear brakes. This car had set up for 4yrs and all the brakes were froze up. I replace all the brakes and wheel cylinders and master. The proportional valve is the one with 8 lines hooked to it. Any way to check the prop. valve? Front brakes work ok.
     
  2. rosco72z

    rosco72z Veteran Member

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    did you bleed your master, you will have to bleed it if it is new
     
  3. haroldpo6

    haroldpo6 Veteran Member

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    Yes, bench bled it.
    The old master cylinder was all dryed out of fluild, so the prop valve could have been too.
     
  4. ol' grouch

    ol' grouch Veteran Member

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    I've never had problems with the proportioning valve when the system was empty. Usually it's air lock. The air will move back and forth rather than move out the bleeder.

    Like a previous poster asked, did you bench bleed the master cylinder? If not, you need to do this first. There are tricks I've used to do it on the car but it's from years of experience and if you aren't careful, you can get brake fluid all over the car body. Brake fluid makes an excellent paint remover.

    Once the master cylinder is taken care of, go to the right rear wheel and bleed it the old fashioned way. Have plenty of brake fluid on hand as you will go through a lot of it. Get a section of clear plastic hose that fits snugly on the bleeder. Loop it up and over then down into a clear bottle of some type. I like old Maple syrup bottles as they have a neat little fake handle that works great to use a wire to hold it up. Now, put something over the master, usually the lid but DON'T lock it down. Fill the bottle about 1/3 of the way with fresh fluid. Make certain the hose goes into the fluid. This keeps it from sucking air back. Open the bleeder valve. Now press the brake pedal down about half way. Hold it for a moment, then raise your foot quickly and press it down again. Keep doing this and eventually, you'll see fluid and bubbles coming out of the bleeder. This will show up as fluid in the hose with bubbles in it. That's why you have the loop, to hold the bubbles at the top. They will eventually clear out and you'll have fresh fluid coming through. Check the master from time to time so it doesn't run dry. The lid contains a little squirt of fluid when you raise your foot and press again from getting on the paint.

    When you're getting fresh fluid out of the right rear, move to the left rear and then right front and then left front. Once you have fluid at all four wheels, go back and do a final bleed. This will get any trapped air out. I use a very small brass hammer to tap the steel lines and knock any bubbles of air loose. You might get done in an hour or it might take 2 or 3 hours. Just take your time and you'll have firm brakes eventually.

    I'm trying to distill 40 years experience in a short post so hopefully I didn't leave something critical out. Just use common sense, unless your a politician and don't have any. :rolleyes:
     
    Last edited: Nov 29, 2015
  5. 71flh

    71flh Veteran Member

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    Is the brake light on and is the (brown?) wire connected on the block or prop valve?

    At the front of the PV there's a rubber plug, and behind that is the end of the valve that can move front or back when pressure's lost in one half of the system (like when you bleed).
    The manual says to use a tool (you can make one) to keep the end from moving while bleeding. I'd guess yours moved and shut off fluid from the rear, as its supposed to.
     
  6. haroldpo6

    haroldpo6 Veteran Member

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    I have read that the 70 was the only year that had this type PV. I can't find a rubber plug on this one.
     
  7. ALLZS

    ALLZS Member

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    Check The Rear Rubber Hose Just Worked On A 71 With The Same Problem And The Hose Was Swelled Shut Not Let Any Fluid To The Rear Wheel Cyls
     
  8. 81BirdMan

    81BirdMan Veteran Member

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    A 1970 has a separate distribution block / metering valve. 1971 and up use the proportioning valve with that aforementioned button on the end (under a rubber plug). Definitely check if fluid is making it to (and through) the rear hose as ALLZS recommended.

    http://www.nastyz28.com/forum/showthread.php?t=268031

    1970 setup:

    [​IMG]

    Proportioning valve with button on left end:

    [​IMG]
     
  9. haroldpo6

    haroldpo6 Veteran Member

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    Mine looks just like the one your posted for the 70 model. Will check rubber hose. Also thinking about taking MC back off and bench bleeding again and blowing thru line with air while I have it off.
    I drove it for the first time ever today after restoring it for a year, and you must have the rear brakes to help stop.
     
    Last edited: Nov 29, 2015
  10. hogg

    hogg Veteran Member

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    i also had that happen to me ,like to never figered it out ,, Was the same as ALLZS had, changed the rubber line at rear , worked fine after that ,, i have changed over to rear dis brakes sence , got all that stuff some where for a 70.
     

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