AF: 1987 Omni brake proportioning valve | Allpar Forums
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

1987 Omni brake proportioning valve

Discussion in 'L: Horizon/Omni, Rampage, etc' started by chadnyne, Sep 21, 2019.

  1. chadnyne

    chadnyne Active Member

    Joined:
    Aug 8, 2013
    Messages:
    31
    Likes:
    2
    anyone have a suggestion for a replacement brake proportioning valve for an 87 Omni? Don’t appear to be obtainable. Are any of the universal ones a direct fit?
     
  2. GLHS60

    GLHS60 Well-Known Member

    Joined:
    Jun 23, 2008
    Messages:
    1,785
    Likes:
    584
    It looks like 4313266 is the Chrysler part # and it should have a grey tag.

    1987 Dodge Omni Lines & Hoses, Brake - Mopar Parts Giant (at https://www.moparpartsgiant.com/parts-list/1987-dodge-omni/brakes-service-lines-hoses-brake.html )

    Grey L, J, P body


    L body: Omni/Horizon: J body: LeBaron/Lancer P body :Shadow/Sundance

    Some with front disc rear drum should be compatible if lconsidering used.

    They seldomly fail so new aren't often available.

    These have diagonal braking so universal might br a challenge.

    What happened to yours??

    Thanks
    Randy



    Differential and Proportioning Valves from: Mini-Mopar Turbo Performance (at http://www.minimopar.net/perf/brakes.html )

    Brake systems distribute the pressure from the master cylinder through a differential valve. These function by splitting the two master cylinder outputs between the left-front and right-rear brakes and vise versa. This way if one set fails, the other set can still stop the vehicle because the brakes are split diagonally from each other. In most cases, pressure to the rear brakes has to be reduced. This is accomplished through a proportioning differential valve. There are several different proportioning valves available, depending on the brake system combination your vehicle has. They function by reducing the amount of brake fluid pressure to the rear brakes after a certain input pressure point, called the split point. The ratio by which the rear brake pressure is reduced after the split point is called the proportioning slope. The lower the slope value, the more the pressure to the rear brakes is reduced. So, if you find that your rear brakes tend to lock up prematurely, then you need a valve with a lower slope and/or lower split point. A perfectly balanced brake system does not need a proportioning valve. Instead these use a basic differential valve that have no proportioning feature, and therefore have no split point and have a slope of 1. Stock proportioning valves are identified by the color of the indent tag. Below is a chart of available valve configurations.

    Tag Color Function Material Split Point Slope
    (none) Differential Brass - 1
    Grey Differential-Proportioning Brass 500psi 0.27
    Tan Differential-Proportioning Brass 600psi 0.43
    White Differential-Proportioning Brass 750psi 0.43
    Black Differential-Proportioning Brass 800psi 0.59
    This table shows some of the vehicles that these valves were used in. Some bodies had different valves depending on their brake configurations (disc/drum, disc/disc, ABS, etc) and specific body styles (2-door, 4-door, etc).


    Tag Color Bodies
    (none) E
    Grey L, J, P
    Tan K, P
    White G, H
    Black G, K
     
  3. chadnyne

    chadnyne Active Member

    Joined:
    Aug 8, 2013
    Messages:
    31
    Likes:
    2
    Have no pressure to passenger front only
     
  4. chadnyne

    chadnyne Active Member

    Joined:
    Aug 8, 2013
    Messages:
    31
    Likes:
    2
    Read somewhere issue could be collapsed brake hose. Will try replacing this first since it is a $3 part...
     
  5. ImperialCrown

    ImperialCrown Moderator
    Level III Supporter

    Joined:
    Jun 8, 2008
    Messages:
    20,535
    Likes:
    3,867
    Is the red 'BRAKE' light on and do you have fluid flow to the driver's rear brake wheel cylinder bleeder?
    It could be that the 'shuttle' in the proportioning valve is forced to one side? This would shut off flow to a diagonal braking circuit.
     
  6. chadnyne

    chadnyne Active Member

    Joined:
    Aug 8, 2013
    Messages:
    31
    Likes:
    2
    No brake light on
     
  7. GLHS60

    GLHS60 Well-Known Member

    Joined:
    Jun 23, 2008
    Messages:
    1,785
    Likes:
    584
    Typically a collapsed hose will prevent the caliper piston from retracting.

    This normally results in the brake staying on not off, just like a stuck caliper.

    Stuck calipers normally result in the brake stuck on, not off, but anything is possible.

    As IC asked, do you have flow to the LR??

    And is the brake warning light functioning otherwise??

    IIRC, with ign on, grounding the wire that attaches to the prop valve should turn the light on.

    This test verifies the bulb and wiring etc. is capable of warning owners of hydraulic problems.


    Thanks
    Randy
     
  8. chadnyne

    chadnyne Active Member

    Joined:
    Aug 8, 2013
    Messages:
    31
    Likes:
    2
    Bought car with stuck caliper. Stuck on. Replaced caliper but noted no brake fluid coming out of the hose when I detached it. No fluid even with power bleeder.
     
  9. chadnyne

    chadnyne Active Member

    Joined:
    Aug 8, 2013
    Messages:
    31
    Likes:
    2
    Per the brake light grounding test, brake light is working. The brake light has not been on otherwise. I will check flow to the LR when I get a chance
     
  10. GLHS60

    GLHS60 Well-Known Member

    Joined:
    Jun 23, 2008
    Messages:
    1,785
    Likes:
    584
    That sounds more like possible hose issue.

    Thanks
    Randy
     
    Gerry G and Bob Lincoln like this.
  11. chadnyne

    chadnyne Active Member

    Joined:
    Aug 8, 2013
    Messages:
    31
    Likes:
    2
  12. chadnyne

    chadnyne Active Member

    Joined:
    Aug 8, 2013
    Messages:
    31
    Likes:
    2
    Just a follow up, replaced hose to caliper and brake line which resolved this. Proportioning valve was not at fault
     
    ImperialCrown likes this.

Share This Page

Loading...
 We are not affiliated with FCA. We make no claims regarding validity or accuracy of information or advice. Copyright © VerticalScope Inc. All rights reserved.