Proportioning Valve?

Brakes for your Classic Mopar

  1. jar84203

    jar84203 Member

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    I have a 71 Duster that has been converted to 73 front disc brakes. My question is should a proportioning valve be installed to get proper brake pressures to the front and rear? From the looks of it, the previous owner never did. All I found was the brake light warning switch that illuminates the dash light if there is low brake pressure in one of the systems. Thanks in advance.
     
  2. 6dart9

    6dart9 Well-Known Member

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    Is that switch in a brass block with the lines going to it?
     
  3. jar84203

    jar84203 Member

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    Not sure if it's brass, but all lines go into it. It's mounted on the framerail just below the master.
     
  4. 6dart9

    6dart9 Well-Known Member

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    That is your prop valve so you should be ok then. Let me see if I can find a pic for you
     
  5. 1967DartGT

    1967DartGT Well-Known Member

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    I was told, when I swapped 73+ disks into my Dart, that I should grab the proportioning valve from the 73+ as well.
     
  6. 6dart9

    6dart9 Well-Known Member

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    Yea I just re read your original post I would find out what 1967dartgt is saying to make sure it's done right.
     
  7. jar84203

    jar84203 Member

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    Yeah a pic would be great that way I know what I'm looking for at the swap meets.
     
  8. 340mopar

    340mopar Sorgermotorsports

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    The brass block is really a distribution block. The proportioning is done with wheel cylinder / caliper piston sizing. When I do a conversion I use the distribution block from the disc car just because I have it but one time used the drum distribution block to see and the brakes worked fine and the braking bias seemed "normal".

    Proportioning valves actually limit pressure to the back brakes to keep the bias towards the front. When you get your conversion done take it out and do a hard stop. If the back brakes lock up before the front then you will need a proportioning valve.

    I really wonder if they are indeed the same. If someone had an old parts book they could see if they were the same part number.


    Chuck
     
  9. 6dart9

    6dart9 Well-Known Member

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    this is what 340mopar is referring to

    DSCF1838_Medium_.jpg
     
  10. jar84203

    jar84203 Member

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    Mine is vertical and a little different. I'll try what 340mopar suggests and add a proportion valve if needed. Thanks
     
  11. 65 Dartman

    65 Dartman FABO Gold Member FABO Gold Member

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    If you have just the distribution block for drum brake cars, add an adjustable proportioning valve to the rear brakes and adjust as needed.
     
  12. jar84203

    jar84203 Member

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  13. hemi71x

    hemi71x FABO Gold Member FABO Gold Member

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    Here is a picture of a valve and lines, off a car that might be of help to you.
     
  14. Purple Haze

    Purple Haze Well-Known Member

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  15. 2 Darts

    2 Darts A-body Addicted

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    The brass block, or Tee (as it is called in the Parts Manual) is fitted with valves as installed in the A-body. In addition, it contains the switch the activates the BRAKE warning light on the dash.

    From looking at the parts manual, the rear wheel cylinder size is a function of the diameter of the drum. The 9" brake used one size piston, 10" & 11" brakes use another. There is no difference whether the car had disk or drum front brakes. Also, there is no difference in the front caliper piston size as relates to the drum size fitted at the rear.

    No. For the A-body, the parts numbers are 3420 021 for the drums, 3549 947 for discs in the 72 manual.
     
  16. Mopar King

    Mopar King Beginner / Need of Help

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    I was wondering what is the right size adapter for the front brake line of the proportioning valve? The proportioning valve on the top there is a tube sticking up and I can't get the right fitting to push it down. I bought a couple of lines but it didn't fit to screw on. the car is still using the original proportion valve. I was just wondering :)
     
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