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got 14 bolt in now have disks on and have a prob??

Discussion in 'The Garage' started by chulisohombre, Apr 2, 2003.

  1. chulisohombre

    chulisohombre 1/2 ton status

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    is there something in the propor valve that holds pressure in the rear brakes?i thought i heard something about it but was hopeing mine was worn out or something.my rear brakes have pressure on them now and dont turn.dont want to ruin my new toys before i have a chance to use them.anybody help?
     
  2. DesertDueler

    DesertDueler 1/2 ton status

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    You need a prop. valve for disc brakes front and rear.

    Dan
     
  3. KrebsATM02

    KrebsATM02 1/2 ton status

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    You can gut the stock proportioning valve to get rid of the reidual valve. If the write up isn't in the technical forum, it is in the bloody knuckle. You have to be a member to access it, but this question is exactly why i joined. I had no time to research it, and as broke as i am, i forked out the 25 for the information. Well worth the money!
     
  4. 45acpJr

    45acpJr 1/2 ton status Premium Member

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    That write-up is part of Grim's write-up on our 10/12 Bolt disc brake article. It's on the front page /forums/images/graemlins/thumb.gif
     
  5. Desert Rat

    Desert Rat Fetch the comfy chair

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    I plan on just buying a replacement from Inline Tube. Mine is pretty shot anyway and I did the rear disk conversion. I'm going to replace all the brake lines and fuel lines with stainless steel and will use their proportioning valve. You can see it here: http://www.inlinetube.com/Prop%20Valves/VCT104.htm
     
  6. Mudstud

    Mudstud 1/2 ton status

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    It seems that I've heard that you can run the front discs straight (no valve) and run the rear through a valve--the stock one or an adjustable one though, I'm not sure. Anybody?
     
  7. bablazer73

    bablazer73 1/2 ton status

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    Thats how i did mine. straight to the fronts, and adjustable valve to the rear. There is no failsafe though.
    Using a regular valve would be better, but I had the valve.
     
  8. ntsqd

    ntsqd 1/2 ton status

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    I see lots of confusion and dis/misinformation here.

    There are three valves commonly in a brake system.

    Proportioning valve - Regulates the pressure to the REAR brakes only. (Some special applications are different, but not on street driven vehicles.) OE are usually fixed proportioning rate, aftermarket have an adjustable proportioning rate. Must be installed downstream of the valve mentioned next.

    Shuttle Valve - turns on the brake warning light when one half of the system fails and theoretically blocks off the leaking/failed half.

    Residual Pressure Valve (RPV) - maintains a little bit of pressure in the line when your foot is not on the brake pedal. Most common on drum brake apps, used to keep the springs from completely retracting the shoes and causing a long pedal travel b4 the brakes function. In some cases they are needed in disc systems where the m/c is below the calipers. Drum versions typically keep 10 psi in the line. Disc versions only keep 2 psi in the line.

    Rear disc conversions can sometimes suffer from the rear RPV still being functional. It will cause the rear pads to drag. The RPV(s) are usually located in the m/c under the little brass cone that the outlet lines seal on. The easiest way to remove them is to run a small tap down the hole. When the tap bottoms out, keep screwing. This will pull the cone out so that you can remove the valve core. Re-install the cone and you're ready to try again.
    Any old flex hose in the system can also cause a dragging condition. They develop 'flappers' in them sometimes, and these flaps act like check valves holding pressure in the line.
     

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