HELP with master cylinder 4 wheel disc

Brakes for your Classic Mopar

  1. dodge71demon

    dodge71demon Well-Known Member

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    For those that have done this I'm looking for help on what master cylinder to use
    I have power brakes - 73 + disc on front + Right stuff disc on the rear.
    prefer 4 bolt but not a must no high dollar mc---thanks

    I see where some are using the mc from a 85 fifth avenue with the adapeter plate
    and they say it works good ?????????????
     
  2. Sedanman

    Sedanman 67-9 Valiant specialist

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    Just use a 4 wheel drum master in the 15/16-1" bore. A disc prop valve isn't required for 4 wheel disc.
     
  3. 65 Dartman

    65 Dartman FABO Gold Member FABO Gold Member

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    Doesn't the drum master cylinder have residual valves that need to be removed or do I have it bass ackward?
     
  4. salinasjoel

    salinasjoel Learning Daily

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    why no prop valve? Just curious... Will it be 50/50?
     
  5. dodge71demon

    dodge71demon Well-Known Member

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    Thanks I'm looking at 69 - 70 with 10 or 11" drum brakes Rockauto has several to choose from prefer new which they gave
     
  6. BrianT

    BrianT Let's go!

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    I'm running this one from Dr. Diff on mine. Stock style discs on front and Master Power discs on back. Stock proportioning valve (disc/drum) was used.

    [​IMG]
     
  7. Sedanman

    Sedanman 67-9 Valiant specialist

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    With 4 wheel disc it will be 50/50 so no disc prop valve needed,just make sure it is for 4 wheel drums. They don't have a residual valve. This has come up a lot in the past few months here and those threads should still be up.
     
  8. Sedanman

    Sedanman 67-9 Valiant specialist

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    I tried locating the threads with no luck,try google searching mopar abody 4 wheel discs or disc swap.
     
  9. AJ/FormS

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

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    Sedanman; check post 7 re the residual valve, in a drum m/c.
     
  10. famous bob

    famous bob mopar misfit

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    85-87 5th ave., standard dist. block manual brakes, offset mastercyl. adapt.(for big heads)
     
  11. AJ/FormS

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

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    Hi there Famous Bob
    Just wondering how your post relates to mine.
     
  12. dodge71demon

    dodge71demon Well-Known Member

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    Thanks I have ordered a new RAYBESTOS MC36221 master cylinder
    for big drum brakes with a booster hope it works
     
  13. AJ/FormS

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

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    To joel; why no prop valve? Just curious... Will it be 50/50?
    It would be, if all pistons were same size. Typically, however,the fronts are way more powerful. Typically the fronts do upwards of 80 % of the braking. If the back gets to be too powerful and locks up first, then spin outs are imminent.Not good at any speed.:eek:ops:

    And to OP; when you receive your new m/c, check it for residual valves. Remove any that you find, from ports destined to have discs. If you do not theres a very good chance that the pads will remain dragging on the discs.
     
  14. salinasjoel

    salinasjoel Learning Daily

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    thanks... So running a prop valve is not a bad idea... How do you check for the residual valves?
     
  15. dodge71demon

    dodge71demon Well-Known Member

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  16. AJ/FormS

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

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    Well I can think of at least 2 ways. Since the valve is just a rubber flapper;
    1) Try to push a tag-wire into the piston cavity
    2) Try to blow through the port
    3) pull the seats out and look
    Oh, wait, thats 3
     
  17. 1qwikScamp

    1qwikScamp Well-Known Member

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    You will need an adjustable proportion valve just to set the front to rear bias
     
  18. GMachineDartGT

    GMachineDartGT Senior Member

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  19. dodge71demon

    dodge71demon Well-Known Member

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  20. BrianT

    BrianT Let's go!

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    I've had those calipers on the rear of my Dart for a while now and have no problem with them but I don't run them hard like I'm sure I lot of other people do. I think they got a bad rap in the eighties because people didn't use their emergency brakes and the calipers get out of adjustment then the adjusters eventually seized up and you're right they were junk. I keep an eye on mine and pull the emergency brake twice every time I take the car out.

    My kit came with a new proportioning valve and the instructions called to take it apart and turn it into a distribution block. My brakes work good with no lock up. But again, I'm not auto crossing it or anything. Just normal street driving to cruise nights and such.
     
  21. GMachineDartGT

    GMachineDartGT Senior Member

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    I did just that, removed the internals from the prop valve, used front pin type calipers and 1 1/32 mopar master, bled as instructed (bleed valve isn't at the top of the caliper) and felt the brakes were pretty crappy...I think the piston in the rear is just too large and the mopar master can't fill the volume properly.
     
  22. dodge71demon

    dodge71demon Well-Known Member

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    Ok for anyone interested here's what I did and found. First the old MC used is one for disc/drum ended up tapping the hole and using a screw and nut as puller removed what ever it's called (from drum side) no residual valve found I presume it probably has to do with the proportioning valve with this set up so onward and upward to the next step
     
  23. Jhenry70

    Jhenry70 Well-Known Member

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    Looking through this thread trying to find answers for my build as well. Maybe you guys can see if I'm headed in the right direction. 72 Duster non/power drum originally. Converting to disc off of 77 Aspen up front with rear mounted calipers. Using a shortened 8.8 rear off of a 94 Explorer disc set up in the rear... plan on getting the MC setup from Dr. Diff http://www.doctordiff.com/aluminum-master-cylinder-kit.html and the adjustable proportioning valve from them as well http://www.doctordiff.com/adjustable-proportioning-valve.html --- I'm planning on running all new lines and flex lines since most of my originals have had some damage, Do I need to ditch the stock prop/dist valve or can it be used as a distribution block and then just put the adjustable in line to the rear? Do I need to get a different dist block instead? Staying with Non-power MC.
     
  24. BillGrissom

    BillGrissom Well-Known Member

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    Jhenry70,
    Good plan and good research. The block in your Duster is a "distribution & imbalance warning" block. It does not have the proportioning (rear) and metering (front) functions of the "combination valve" on factory disk cars. Yes, you can re-use it, and should since it keeps your dash imbalance warning lamp working. Yes, you also need an adjustable prop valve to the rears ($30 cheap), and it must be after the imbalance switch to keep that working correctly (i.e. install it down in the mud). You could also replace both with a combination valve, but pricey and non-adjustable.

    Your drum MC would actually work. It just doesn't have as large a reservoir for the disks. Also, some have a "residual valve" on the outlet ports that would need to be pulled out so the disks don't drag. Many MC's would work. I am putting a new one for a 99 Breeze w/ ABS ($25) on my 65 Valiant w/ manual brakes, via a 2-4 adapter plate ($30). Many use an 80's Dodge truck MC w/ same adapter, which is what the Dr Diff setup looks like. You could buy the same parts cheaper on ebay, but his price isn't painful. I abhore rust in my brake components, so use silicone fluid in all my non-ABS cars.
     
  25. Jhenry70

    Jhenry70 Well-Known Member

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    Thanks for the information! Very helpful to a newbie like me. My original MC was missing in action when I got the car so I will be getting a new one any way. I'll check into the truck MC's. I see you're in Sacramento... I'm just up Hwy 99 in Yuba City. Good to see some local guys around for resources.

    Jerry
     
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