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Thread: Proportioning valve cause soft pedal feel?

  1. #1
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Proportioning valve cause soft pedal feel?

    Trying to get the brakes right on the black Daytona. Disc/drum setup, I've put new wheel cyl's in the rear, a new caliper up front (one was sticking), and now a master cyl. Before the master it would stop but felt pretty spongy and seemed like the right rear and left front were grabbing weren't grabbing right. Was thinking the master may have only been working on one circuit so replaced it. It now feels better and stops better, but still seems like that right rear isn't fully engaging, maybe the front left also? I can hear it scrubbing the drum in the back, changes as you step harder on it but just doesn't seem right.Shoes are old but have lots of material, pretty sure the front pads I changed out when I got the car a couple years ago, no run time on them til now.

    I bench bled the master, system is fully flushed of old fluid. Have not re-bled the whole system again yet after the master swap, may try this just to see if it helps so more. Only other thing left really is the prop valve.
    Rob M.
    '89 Turbo GTC
    2.5 TIII swap is here!

    Project LookOwt
    '91 Daytona ES, 61k original miles, Rick Lozier's old 3.0 nitrous car
    Back to basics, then the mods go back on....

  2. #2
    Supporting Member Turbo Mopar Contributor supercrackerbox's Avatar
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    Re: Proportioning valve cause soft pedal feel?

    I would definitely start by re-bleeding the whole system. I'm always a fan of doing all four corners at once, with clear vinyl tubing running into glass jars. Put just enough fluid into the jars to cover the ends of the tube so they don't suck air while you're pumping the brakes. But this way you'll be able to see if any of the circuits are not pumping.

  3. #3
    turbo addict
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    Re: Proportioning valve cause soft pedal feel?

    Quote Originally Posted by Force Fed Mopar View Post
    I bench bled the master, system is fully flushed of old fluid. Have not re-bled the whole system again yet after the master swap, may try this just to see if it helps so more. Only other thing left really is the prop valve.
    Guaranteed to have air in the system at this point after the master being replaced. Bleed all 4 corners and go from there. Once they are bled you may need to adjust the rear brakes to get the pedal firmer. I normally adjust them so there is just a slight scratch as the wheel is turned.
    “If the people of the nation understood our banking and monetary system, I believe there would be a revolution before tomorrow morning.” -Henry Ford

  4. #4
    boostaholic
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    Re: Proportioning valve cause soft pedal feel?

    is this a car with a dual diaphragm booster? a car with one bad section of the dual diaphragm has given me a spongy pedal

  5. #5
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: Proportioning valve cause soft pedal feel?

    Quote Originally Posted by going4speed View Post
    is this a car with a dual diaphragm booster? a car with one bad section of the dual diaphragm has given me a spongy pedal
    It's a factory auto car, they do have a larger booster, might be dual diaphragm?

    - - - Updated - - -

    Quote Originally Posted by 86Shelby View Post
    Guaranteed to have air in the system at this point after the master being replaced. Bleed all 4 corners and go from there. Once they are bled you may need to adjust the rear brakes to get the pedal firmer. I normally adjust them so there is just a slight scratch as the wheel is turned.
    That's where I have it adjusted now.

    The scrubbing noise I'm hearing is really more of a squeaky noise, sounds almost like worn out shoes but they aren't. Maybe just cause they are old?
    Rob M.
    '89 Turbo GTC
    2.5 TIII swap is here!

    Project LookOwt
    '91 Daytona ES, 61k original miles, Rick Lozier's old 3.0 nitrous car
    Back to basics, then the mods go back on....

  6. #6
    Mitsu booster
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    Re: Proportioning valve cause soft pedal feel?

    Did you get your spongy pedal issue resolved?

  7. #7
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: Proportioning valve cause soft pedal feel?

    Haven't done anything else with it yet, it's a much better pedal after swapping the master, but I still need to bleed it all again.
    Rob M.
    '89 Turbo GTC
    2.5 TIII swap is here!

    Project LookOwt
    '91 Daytona ES, 61k original miles, Rick Lozier's old 3.0 nitrous car
    Back to basics, then the mods go back on....

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