The Right? proportioning valve for rear disk

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blue85, Nov 8, 2001.

  1. Blue85

    Blue85 Troll Premium Member

    Jul 26, 2000
    Likes Received:
    Grand Rapids area
    Now that I've gone 4 wheel disc, I am still confused about what is the right way to plumb everything. The stock proportioning/metering block should be all wrong for this setup. It seems that some people are getting away with it just by the chance that they have chosen a certain caliper or whatever. The adjustable prop valve that many are recommending is NOT a replacement for the factory prop valve, which has two inputs and three outputs. You can only add it in series with the factory valve to cut the already low brake pressure to the rear. It seems that you should do one of the following three things:
    1) get rid of the metering/prop valve and hook the master cylinder right to the brakes, using the adjustable prop valve in the rear line.

    2) Use an Eldorado or camaro distribution block and a) hope that it's right or b) put the adjustable prop on the rear. You could also couple this with the master cylinder from that vehicle.

    3) Open up the end of the factory block and take out the proportioning valve and spring to run full pressure from the master cylinder to the rear brakes. Again, this can be balanced out with the adjustable prop valve. I am not sure yet whether or not this would give proper function of the brake warning light switch.

    What does everyone think?

    Has anyone actually gotten their rear discs to lock before the front using the stock metering/proportioning valve? If so, what calipers were you using?

    I haven't found anyone yet who can get an Eldorado prop valve.

    <font color=green>There's nothing like the smell of a rich V-8 in the morning...</font color=green>
  2. Thumper

    Thumper 1/2 ton status

    Feb 17, 2000
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    Alberta Canada
    Well, I have finally got mine workin right... almost. I used the stock front rotors, calipers, back plates on the back 12 bolt. I removed the rear line completely from the dist/ prop valve, and ran it straight back to the rear calipers. It works good, but I can lock the rears before the front if I get on them hard. I am afraid that when the snow hits and things get slippery, it will send me spinnin around when I put them on any harder than a normal stop. I am planning on picking up an adjustable valve for the rear as soon as I can. My "Brake' warning light is on all the time... Im going to just pull the wire off the stock valve. Other than that... it works pretty well.


    <font color=blue>Thumper
    85 Fullsize Jimmy
    <font color=red>Aint Skeered!! </font color=red>
  3. prjt_blzr

    prjt_blzr 1/2 ton status

    Mar 4, 2001
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    COS, CO
    I'm using the eldo prop valve. Unfortunately the truck is not able to move under its own power yet. The eldo valve is nothing more than a splitter with the idiot light switch for the brakes from what I recall. I have also plumbed in an adjustable prop valve so that the rear brakes can be dialed in. I got my valve from GM a while back without a problem.

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