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HELP!! Brake question: still having trouble

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Thumper, Aug 18, 2001.

  1. Thumper

    Thumper 1/2 ton status

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    This is after my disc swap on the rear.
    I am still getting no pressure to the rear calipers. There isnt any air in the system, I bled them at the main T, then at the flex line to the caliper, then at the bleed screw. The little pin on the proportioning valve pops out every time I press the brake pedal. BTW, all the above bleeding was done with the little pin held in by a clamp. When I remove the clamp, it still pops out. The 'BRAKE' light is on steady, and the pedal is really crappy feeling. Does this mean that the valve is shot? The front brakes work good, and when I bled them, it felt normal... ie. the pedal would dump to the floor when I open the bleeder, but when I open the rear bleeder, it doesnt dump to the floor. It seems the problem is that its shutting down the rear brakes, but isnt the little pin on the valve supposed to be a manual bypass to get the back to work? I am lost and frustrated. Does anyone have any ideas?
    Also, to the guys that have swapped to discs before... did you have to change the master cylinder or the prop valve for them to work??

    Any help is appreciated.

    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Aint Skeered!! </font color=red>
     
  2. Thumper

    Thumper 1/2 ton status

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    Anyone?

    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Aint Skeered!! </font color=red>
     
  3. Triaged

    Triaged 1/2 ton status

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    Try giving Steve Chin a PM. He hangs out on the 1st gen board and knows alot about disc conversion.

    '71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
     
  4. dragricinMT

    dragricinMT 1/2 ton status

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    I have the WARN 12b full float kit andd the disc brake bracket kit and they recomend a adjustable proportioning valve for the rear disc brake set-up. The disc calipers need more pressure than the wheel cylinders do. I have been told it can be done with just the factory prop valve but not always. The adj. prop valve is only 50.00 and I would try it.
     
  5. FWP

    FWP CRS

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    Sounds like the combo valve(on the front frame) is stuck to one side actuating the warning switch. Open up one of the fronts again to see if you can't "reset" it back to center.

    <a target="_blank" href=http://coloradok5.com/gallery/75K5>http://coloradok5.com/gallery/75K5</a>
     
  6. Thumper

    Thumper 1/2 ton status

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    Thanks lots... the adjustable valve according to a friend is 150.00 up here, so I will try to find one for cheaper. Summit has one for 38.00 US, so that may be an option as well.

    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Aint Skeered!! </font color=red>
     

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