Brake Combination Valve

Discussion in 'Camaro Questions' started by RRD, Jun 17, 2005.

  1. RRD

    RRD Veteran Member

    256
    0
    Oct 17, 2000
    Sanford, MI.
    This is also referred to as a proportioning valve or control valve and is located under the master cylinder. Can anyone tell me if it is normal for the pin to move out when the brakes are applied ? From everything I have read this shows it to be failed and that it cannot be serviced. Problems with the brake light staying on resulted when bleeding the system after a master cylinder install. There is also a difficult time getting much pressure to the back brakes after bleeding. Any information regarding this would be appreciated

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    Ryan
     
  2. 73454

    73454 Guest

    Have you pushed the pin back in? This usually cures the problem. Prop valves usually don't just fail all of a sudden. They usually fail slowly over a number of years. You still likely have air in the lines. Did you bench bleed the master cylinder?
     
  3. RRD

    RRD Veteran Member

    256
    0
    Oct 17, 2000
    Sanford, MI.
    Thanks for the reply. Yes I did push this back in and and still moves in and out when braking The master cylinder did get the bench bleeding. This is a 1st for me for I have never seen this problem before. I did remove the brake switch on the valve (for cleaning) and installed back with no problems, unsure if failed the unit ? I did remove the valve and cannot find anything wrong from the outside. I will try bleeding them again and go from there.

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    Ryan

    [This message has been edited by RRD (edited June 17, 2005).]
     
  4. RS_SS350

    RS_SS350 Veteran Member

    well, it is supposed to move out when you apply the brakes, but only after you have pressed it in, like when bleeding brakes. it should not be moving in and out. if you're looking to replace it, http://www.inlinetube.com/ has them, but you will also need to buy a new switch connector because the old one does not fit the new switch...
     
  5. rscamaro73

    rscamaro73 Administrator Staff Member

    OK....SOMEONE needs to hold down that button WHILE you're beeding the brakes. Otherwise its just wasting your time....

    I JUST got done swapping a M/C and booster & prop valve a few weeks ago and found out the hard way. Wife was PISSED she had to pump the brakes so many times...lol...

    Really though....in my 73 maintenance manual, it shows a picture of a special clip on the prop valve that has a little finger that pushes the button in while doing this. Once I got the button pressed in...the job took no time at all. [​IMG]
     
  6. RRD

    RRD Veteran Member

    256
    0
    Oct 17, 2000
    Sanford, MI.
    I bled the system (with the metering rod pushed in) and yet still having problems. The rod still moves out when the brakes are applied and there is not much pressure to the back brakes. The switch is working fine now. The only thing I did was take the switch off the valve to clean it up and then reinstalled everything. I find it hard to believe that this caused any failure on the unit. Is it possible that now the master cylinder has a leak and will not get enough pressure to the back? I have looked into a new combination valve, however they are a totally machined block now and I need the correct look. Any ideas ?

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    Ryan
     
  7. towhog

    towhog Veteran Member

    507
    0
    Mar 30, 2003
    Oak Harbor Wa.
    RRD get a small 90 degree braket or make one. place the brack on the proportioning valve so that the bracket holds the pin on the end of the valve in and will not let it move out. Use a vice grip plyers to hold it place. Then start to bleed your brakes. Start with the wheel that is farthest from the master cylinder, then the next farthist and so on. You do not have to push the brake peddel to the floor or push it to hard. Just use your hand to push it in 1/4 to 1/2 or untill you fill pressure against your hand. (you may not get much pressure at first or fluid). Then hold it in that position. Have some one help you to bleed the wheel cylender. Make sure that the brake pedel does not move out at all untill the bleed valve is closed. Go esey at first. You may not feel much pressure at the start just keep working around all the wheel cylenders. Make sure that the master cylender stays full don't let it get to low. After you get fluid from all wheel cylenders and a good feel on your peddel you can take the bracket off and see if the pin does not move. Make sure that the master cylender is bleed befor you hook the lines up to your brake system. I beleave that you may have pushed the brake beddel to far alowing the proportioning valve to over extend. Most of the time when this happens you will feel a click or pop in the peddel and the it does not feel right after that. The valve has blocked of the back brakes as if you had a leak keep the rest of your fluid in the front side of the system. In is made to work that way. Rember don't push your peddel to far or to hard, and don't let the peddel move out befor the bleed valve is closed. Your braks will come back. If you have any questions just e mail me.
     

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