1. 44067gtdart

    44067gtdart Well-Known Member

    Messages:
    193
    Likes Received:
    50
    Joined:
    May 22, 2014
    Location:
    Nevada
    Local Time:
    12:57 PM
    Is the proportioning valve a direct replacement for the distribution block on a 1971 Dodge Dart Swinger? Will I need to use adapters or buy new lines? I did switch to a proportioning valve on my 67 Dart, and I believe everything bolted up without any modifications.
     
  2. Dana67Dart

    Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

    Messages:
    5,571
    Likes Received:
    3569
    Joined:
    Jul 16, 2017
    Location:
    Northern Colorado
    Local Time:
    11:57 AM
    upload_2021-1-11_9-3-15.png

    I say... Can't tell with out knowing what "proportioning" you are referring to.

    In 67 there was a proportioning valve and a seperate distro block. Some where in the later years they replaced the 2 seperate parts with a combo unit.
     
  3. 44067gtdart

    44067gtdart Well-Known Member

    Messages:
    193
    Likes Received:
    50
    Joined:
    May 22, 2014
    Location:
    Nevada
    Local Time:
    12:57 PM
    Car now has 4 wheel drum brakes. Upgrading to Kelsey Hayes front disc brakes. Same thing I did with my 67 Dart. I believe I just took the distribution block out and bolted the proportioning valve in place. I just didn't know if the 71 was the same. On the 67 I believe I just had a distribution block.
     
  4. Mattax

    Mattax Just the facts, ma'am FABO Gold Member

    Messages:
    11,263
    Likes Received:
    7126
    Joined:
    Feb 7, 2013
    Location:
    Phila. Pa
    Local Time:
    1:57 PM
    • Thanks! Thanks! x 1
    • Agree Agree x 1
    • Dana67Dart

      Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

      Messages:
      5,571
      Likes Received:
      3569
      Joined:
      Jul 16, 2017
      Location:
      Northern Colorado
      Local Time:
      11:57 AM
      Based on what Mattax posted, your car has the combo type valve so I would assume that you can just bolt in a 70 up combo valve
       
    • 44067gtdart

      44067gtdart Well-Known Member

      Messages:
      193
      Likes Received:
      50
      Joined:
      May 22, 2014
      Location:
      Nevada
      Local Time:
      12:57 PM
      Great news. Thanks for all the help guys.
       
    • Mattax

      Mattax Just the facts, ma'am FABO Gold Member

      Messages:
      11,263
      Likes Received:
      7126
      Joined:
      Feb 7, 2013
      Location:
      Phila. Pa
      Local Time:
      1:57 PM
      Not with a drum brake car.
      A factory disk equiped car built after Jan 1 would have come with the combo valve.
      When converting the fronts to k-h fixed calipers use either
      the original safety with a proprtioning valve in the rear line (as was done '67-69)
      or
      a combination valve.

      Factory valving works well with matching factory rear brakes; or depending on shoe and pad linings, tires, pavement, etc., sometimes slightly smaller rear wheel cylinders.
       
    • Dana67Dart

      Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

      Messages:
      5,571
      Likes Received:
      3569
      Joined:
      Jul 16, 2017
      Location:
      Northern Colorado
      Local Time:
      11:57 AM
      My reasoning was the 71 would have had a combo valve or a distro block but both would have the brake warning switch in it. If the OP has a post 70 combo valve I assume ( and we know what that means) if he had a drum / drum distro /brake warning block that the combo valve would be a bolt in.

      Again it was an assumption that the factory would have used the same hard lines for either disk or drum to save money and the combo valve / distro block would have the same mounting and inlet / outlet locations would be the same.

      I could be 100% wrong and they made them unique to prevent a distro block being put into a disk brake car.


      I'm so confused!
       
    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

      Messages:
      19,947
      Likes Received:
      7568
      Joined:
      Jan 19, 2014
      Location:
      South-Central Manitoba,Canada, 900ftelevation
      Local Time:
      12:57 PM
      You need to know WHY, you would need a P-valve(Proportioning) or a C-valve(Combination), and what the words really mean.
      So first-off, the definitions;
      A P-valve reduces the pressure to the rear brake cylinders to a percentage of whatever pressure is being sent to the front.
      A C-valve is a P-valve with a safety switch incorporated into it, that can be used to turn on a light on your dash, to tell you that one end (either front or rear) of your system has suffered a pressure loss.
      Now, the reason.
      There is only one reason to run a valve like this, which is to prevent the rear brakes from locking up prior to the fronts. When the rear locks up first, at speed, the rear usually steps out from behind the fronts and quickly sends you into an irrecoverable spin.
      With Drum/drum brakes,and four same-sized tires; the front brake shoes are wider than the front, making them do about 85% of the braking. Ergo, the system is balanced by the engineering of the total shoe contact area, and sometimes the the balance of the W/Cs gets involved.
      But when you install disc brakes on the front only;
      It requires way more pedal pressure to affect the same stopping power because the self-energizing feature of drum brakes is no longer helping, and of course, that, way more pressure is also fed to the rear. And so, the rear brakes have a tendency to lock up first under heavy braking...... with four same-sized tires. And so the P-valve was invented to help prevent that.
      Now; if you have different sized tires from one end of the car to the other, then you will have different proportioning needs.
      Hotrods usually have big fat rear tires, so the proportioning CAN be engineered to send more pressure to the rear for even better braking , in combination with the front discs.
      On my car for instance, a 68 Barracuda;
      On the front I have 235/60-14s, with the KH four piston calipers. and
      On the rear I have 295/50-15s, with 10x2 shoes.
      I found that I could run NO PROPORTIONING at all, AND, I changed the rear w/cs to one size bigger, for more brake-force on the rear. This was done by field-testing, to make sure the back of the car stayed in the back, under the most severe braking situations.
      My rear shoes now wear out faster than my front pads.

      If you are running four same-sized tires, in a disc/drum system, then you NEED a P-valve, period.
      If you have a light on your dash to tell you that the parking brake is on, then you can use a C-valve, and connect it to the light.
      The C-valve from a 73 up disc front brake A-body will work just fine. And if you don't want to wire up the Safety switch, then don't,lol.

      There is only one over-arching caveat, namely, do not let the rear brakes lock up prior to the fronts, because; when the back steps out, you only have milliseconds to avoid a spin-out.

      Ok I hope that helps.
       
      Last edited: Jan 13, 2021
    • satfish

      satfish FABO Gold Member FABO Gold Member

      Messages:
      14
      Likes Received:
      7
      Joined:
      Oct 10, 2011
      Location:
      texas
      Local Time:
      12:57 PM
      Find the Ram Man site. Fort worth Texas has all ya need
       
    • Dana67Dart

      Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

      Messages:
      5,571
      Likes Received:
      3569
      Joined:
      Jul 16, 2017
      Location:
      Northern Colorado
      Local Time:
      11:57 AM
      I think we are getting into semantecs but...


      There are 3 devices that our cars use from the factory.

      1. Distribution block with a brake warning light in it. (Drum/drum)

      2. A distribution block with a brake warning light, with an external proportioning valve. 67 to mid 70, probably earlier years as well. (Disk / drum)

      3. A "combo" valve that has distribution block, brake warning light, and proportioning valve all in one. Mid 70 up, (disk / drum)


      Your points about the rear locking too soon are spot on.
       
      • Agree Agree x 1
      • Mattax

        Mattax Just the facts, ma'am FABO Gold Member

        Messages:
        11,263
        Likes Received:
        7126
        Joined:
        Feb 7, 2013
        Location:
        Phila. Pa
        Local Time:
        1:57 PM
        Not quite.
        They do nothing when the line pressure is moderate.
        They proportionally reduce the increase in line pressure above the set point.
        Yes its used with front disk-rear drum combinations to offset the amplification of braking force of the duo-servo drum system in the situations where heavy braking has shifted the weight to the front.

        That pretty much sums it up.
         
      • Mattax

        Mattax Just the facts, ma'am FABO Gold Member

        Messages:
        11,263
        Likes Received:
        7126
        Joined:
        Feb 7, 2013
        Location:
        Phila. Pa
        Local Time:
        1:57 PM
        That's a logical theory.

        For the OP, going from a 10" drum brake system to a K-H front, with the nominal 10 x 1.75 rear drum, changin to a combo valve very well may avoid having to change or modify the hydraulic hard lines.
         
      • 44067gtdart

        44067gtdart Well-Known Member

        Messages:
        193
        Likes Received:
        50
        Joined:
        May 22, 2014
        Location:
        Nevada
        Local Time:
        12:57 PM
        So what would be the correct combo valve to use? I definitely would like an easy bolt in swap.
         
      • AJ/FormS

        AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

        Messages:
        19,947
        Likes Received:
        7568
        Joined:
        Jan 19, 2014
        Location:
        South-Central Manitoba,Canada, 900ftelevation
        Local Time:
        12:57 PM
        Do you have four same sized tires on the car?
        If yes then any valve off a disc/drum A-body will work.
        You can fine tune it, if you need to, for your application with one of three sizes of rear wheel cylinders, or by the use of braking materials.

        I started with a 73 disc/drum C-valve, and as my rear tires got progressively taller and wider, I eventually just gutted the proportioning part of the block.
         
        Last edited: Jan 14, 2021
      • 44067gtdart

        44067gtdart Well-Known Member

        Messages:
        193
        Likes Received:
        50
        Joined:
        May 22, 2014
        Location:
        Nevada
        Local Time:
        12:57 PM
        215/60/14 front and 245/60/14 rear
         
      • Mattax

        Mattax Just the facts, ma'am FABO Gold Member

        Messages:
        11,263
        Likes Received:
        7126
        Joined:
        Feb 7, 2013
        Location:
        Phila. Pa
        Local Time:
        1:57 PM
        And what rear brakes?

        What other changes?

        Actually probably don't want answer this any more directly than I've indicated above.
        If its stock, then following the factory setup will be the best bolt in all 'round performance.
        The one thing that won't be quite the same is the lining materials (unless you buy old stock and that's got pros and cons). So that's one variable you'll still have to experiment a bit with.

        For not quite stock, or specialized performance use (such as high speed track or circle racing on pavement or loose ) then it may be desireable to have an adjustable proportioning valve. Also another tuning variable that I mentioned earlier is very slightly smaller (or sometimes larger) wheel cylinders.
         
        • Like Like x 1
        • AJ/FormS

          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

          Messages:
          19,947
          Likes Received:
          7568
          Joined:
          Jan 19, 2014
          Location:
          South-Central Manitoba,Canada, 900ftelevation
          Local Time:
          12:57 PM
          215s are pretty skinny fronts,
          and the F/R size differential is pretty small,
          so I would start with a stock C-valve.
          Better safe than sorry.
           
        • 44067gtdart

          44067gtdart Well-Known Member

          Messages:
          193
          Likes Received:
          50
          Joined:
          May 22, 2014
          Location:
          Nevada
          Local Time:
          12:57 PM
          Thanks for all the help.. I will get on it this weekend
           
        • AJ/FormS

          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

          Messages:
          19,947
          Likes Received:
          7568
          Joined:
          Jan 19, 2014
          Location:
          South-Central Manitoba,Canada, 900ftelevation
          Local Time:
          12:57 PM
          As already mentioned;
          the aftermarket makes an adjustable one. This will grow with you if you foresee up-sizing the rear tires. You just plumb it into the rear line wherever it is convenient.
          images?q=tbn:ANd9GcTkLchoRV5wke1A8C65LgQ98nDJZeqJkvElMQ&usqp=CAU.jpg images?q=tbn:ANd9GcR4DlDkg1cxWLb4iKiQ5d-u4jnneXSqU17aEg&usqp=CAU.jpg images?q=tbn:ANd9GcSpcuEx8BYroJMqq_1vKGGMZmuHZCgzNHABmw&usqp=CAU.jpg images?q=tbn:ANd9GcR6eeROKzXeXp1hXtzgf_yhYivcwEz_cHW0Yw&usqp=CAU.jpg
           
          Last edited: Jan 15, 2021 at 11:00 AM
          • Agree Agree x 1
          1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
            By continuing to use this site, you are consenting to our use of cookies.