RABS delete

Discussion in 'The Garage' started by jwilloughby1995, Jul 14, 2017.

  1. jwilloughby1995

    jwilloughby1995 Newbie

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    Hello all I have been reading and hearing about a lot of people with obs chevys deleting the rear abs on these trucks just wanted to see if anyone on here has done it and what's the pros and cons of doing it I have never liked the way the brakes feel on my 90 SCSB 4wd feels like it puts way to much braking power on the front and hardly any on the back


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  2. chipskittles

    chipskittles OBS Enthusiast

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    Pros- firmer brakes - got rid of the mush.
    Cons-
    - Lose your brake light bulb check at startup. If the bulb burns out you would never know if you have a brake problem developing. A leaking wheel cylinder for example is very common and can develop slowly unbeknownst to you unless you check your fluids every day or so.
    - Rear brakes will lock up a LOT easier, especially in the rain. If you are a pro at driving trucks this should be a non-issue.


    I highly recommend this mod. Rear ABS was 90s marketing hype. I have owned a few different model trucks with the Rear ABS and it never worked right, even in the 90s.
     
    Last edited: Jul 14, 2017
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  3. jwilloughby1995

    jwilloughby1995 Newbie

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    Thanks for the reply bud I bought the fitting to do away with the abs today so tomorrow I'm gonna do away with it I'm tired of the mushy brakes on it and it feels like it puts way to much stress on the front brakes also i grew up on non abs brakes so I should be okay in snow and rain lol


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  4. deejaaa

    deejaaa I'm Not Awesome

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    RWAL is the correct term. look it up and you will find:
    What's needed.
    1/2" wrench/socket
    9/16" and 1/2" flare wrench for brake lines.
    5/16" male x 1/4" female brake line adapter fitting. ie, EDELMANN #258450 (available at O'reilly auto parts.....about $5.)
    15 minutes + time to bleed rear brakes.

    Master cylinder has fluid reservoir on top. Isolation dump valve is below(to be removed). To right of that is proportioning valve (keep that). Attached to proportioning valve is control box (black plastic with wired connectors).
    2012-06-09120715b.jpg
    Start by removing control box. Remove connectors from rear. Top one is part of vehicle harness. Lower plug connects to other part to be removed. Jiggle box, pull towards front of vehicle, should slip off.[​IMG]
    Should look like this....
    [​IMG]
    Next, disconnect two lines from bottom of isolation/dump valve...one is very short and connects to proportioning valve. Disconnect from proportioning valve as well. Remove two bolts (1/2") from top of valve where it attaches to bracket.
    [​IMG]
    With that out, its easy to see what's left to do.
    [​IMG]
    [​IMG]
    Fitting from Oreilly, $5.49 allows use of existing brake line and screws into proportioning valve. EDELMANN 258450. Male threads are 5/16", female are 1/4". This is a brake fitting. Can find something similar using these dimensions.
    [​IMG]
    Screw that in bottom of proportioning valve. Use teflon tape and a little bending to reposition and tighten it up.
    [​IMG]
    Bleed Rear brakes and better pedal feel.
    Isolation/dump valve is thought to degrade brake pedal feel and and trap air. System only provides anti-lock for rear wheels, via drum brakes.
    88-94 gets rid of brake light.
    1993 GMC - no adapter needed.
    A rubber button on one end of porp valve- press this to recenter valve.
    One of connectors (4 pin) is removed when deleting isolation/dump valve. Other connector, cut wires at staggered lengths, tuck into wire loom. Orange wire will be hot so if it shorts out, will need to replace 15 amp brake lamp fuse.
    [​IMG]
     
  5. Supercharged111

    Supercharged111 I'm Awesome

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    What does recentering the prop valve do and when is it required? I put one on my 98 when I deleted the also worthless 3 channel ABS from it.
     
  6. jwilloughby1995

    jwilloughby1995 Newbie

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    Well I did the abs delete on my 1990 k1500 and my brakes feel much better ended up not needing a adapter to go into the proportioning valve lines where the same size so no more dump valve and no more abs truck stops on a dime now and doesn't feel like it's killing my front brakes


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