Combination valve

Discussion in 'The whoa and the sway.' started by Mart, Aug 7, 2021.

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  1. Mart

    Mart Gold level member

    Great idea, maybe if I give her a glass of wine while she has to sit there....:D
     
    Waterboy likes this.
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    There's a method to the madness. Good thinking.:D
     
  3. Mart

    Mart Gold level member

    So this "new" info of bleeding fronts 1st, it that only because of the combo valve incorporated into the mix? Will the old standard bleed right rear 1st work or not?
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Nahh, that doesn't matter. Standard bleed will work just fine. Just depress the pin for the whole process. I used a C clamp.
     
  5. jaye

    jaye Well-Known Member

    I finally got around to resetting and installing the bleeder tool. My combination valve is on the frame and I’m working on the garage floor. After I got the fittings out , my bleeder tool is too big. It’s impossible to look into the valve and move the piston back centered. It may already be centered since I pressed the reset button. Now to find the right size tool. I knew I should’ve done this at work where I have a lift
     
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    OK, one more time. The combination valve consists of 3 parts.

    1)The hold off section
    2)The warning light section
    3)The proportioning section.

    CombinationValve.JPG
    The only part that gets centered, is the valve in the middle. The centering depends on equal pressure on both sides. If you pop a brake line, and lose hydraulic pressure on one side (front or rear brakes), the valve moves to one side or the other and grounds the switch terminal lighting the brake light. As soon as pressure is restored, the valve centers itself, and the light goes off. I can actually make that happen by applying my line lock. Pressure is held in the front brake lines, and I take my foot off the brake pedal releasing the pressure in the rear brake lines. My brake light comes on as long as I hold the button. As soon as I release the button, the brake light goes off.

    You don't have to center anything. It centers itself. If it didn't, your brake light would be on.
     
    Last edited: Aug 14, 2021
  7. jaye

    jaye Well-Known Member

    As I mentioned I bled my brakes prior to using the tool and don’t have any pressure to the front , so I assume the piston moved to hold off the back so it’s not centered any longer.
     
  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Once you get pressure to the front brakes, the valve will take care of itself.
     
  9. Mart

    Mart Gold level member

    Are there any guidelines for adjusting the power booster threaded rod that attaches to the brake pedal?
    How can you tell if the booster diaphragm is in a neutral or centered position when relaxed.?
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I used that threaded rod to adjust my pedal height. I always felt the stock pedal height was too low. I don't think it matters to the diaphragm.
     
  11. Mart

    Mart Gold level member

    So probably no noticable differance for booster assist performance adjusting pedal 3 or 4 threads up or down?
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    No, my original booster rod had no threads at all, it was not adjustable. My replacement had threads, and I used them to adjust the pedal height higher. I like it like that, much better feel.
     
  13. Mart

    Mart Gold level member

    Well I tried 3 threads higher pedal, no noticeable change except for pedal height.
    I'm going to stop right there. You know how stupid you feel with your head down by the brake pedal, your rear end on the seat, and your feet hanging over the headrests?
    I'm done crawling around....:D:D
     
  14. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    It's a good thing you can do that without crippling yourself.:D You'd never hear the end of it from you know who.:)
     
    Mart likes this.
  15. gstewart

    gstewart Well-Known Member

    If u can remember back in the '60's I recall sitting in a '66 ford galaxy with power brakes and the brake pedal was so close to the floor board more so than my '72 GS
     

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