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Pontiac Master Cyl Upgrade 1956

Discussion in 'The Hokey Ass Message Board' started by Pontiacres Ranch, Sep 27, 2008.

  1. Pontiacres Ranch
    Joined: Jan 26, 2008
    Posts: 649

    Pontiacres Ranch

    OK, so Im supposed to be headed to Duck Tails yesterday, the Brakes on the 56 Pontiac 2 Door Wagon have been a bit mushy for about 2 weeks. Since the 4 hr trip back from Stanton & the Pure Stock Drags. This week they had been slowly getting worse, a pump or 2 at this stop, 3 pumps at another, next one Is fine depending on speeds. Before I drive the 2 hrs to Duck Tails, I figured Id adjust the Shoes and check the levels. The shoes are dragging nicely, the fluid level is good! I get a buddy to come by and brave the mosquitos to do a quick bleed. No air from any wheel. Quickly came to the conclusion the master cylinder is bypassing the seals. Bottom line, Im not going, not worth killing myself or someone else to go to a show.

    Question to the Pontiac guys with frame mounted single cylinder brakes, anyone know where I can get a replacement in a hurry?

    Anyone upgrade to a Dual Systems? If so What did you use? Got any Pics?


  2. MissPrint
    Joined: Sep 11, 2008
    Posts: 760


    Quite curious on this one too. My master went out on the Edsel Thursday night (driving home, luckily in my parking lot, not on the road) and ordered a single port today to replace it as a temp fix so I can get her on the road by the weekend and head to Kerrville.

    Everyone I've talked to has recommended up grading to a dual system as well. . .I'd like to know what's involved in doing this as well. Thanks!
  3. Crease
    Joined: May 7, 2002
    Posts: 2,878


    Typically, here's how it goes.....

    1) Measure the piston on your old master (it's probably 7/8" or 1")
    2) Find a dual master with the same bore (or close). A smaller piston will make it easier to stop, but be careful cause it might make the pedal go right to the floor. Often a good match is a mid 70s mustang master (finally, there good for somethin'). However, you may need to do some internet searchin or diggin at Auto Zone. If your super resourceful (AKA sneaky), find someone that manufactures a dual or power kit for your car. Call and tell them you need a rebuild kit. They'll tell you "just go buy one at Auto Zone, here's the number". At that point, your set. Even the guys at AZ can now find your master!
    3) The new one sure as heck aint gonna fit, so you need to make an adapter plate. Go big on the plate and use grade 8 bolts, cause......well it's kinda obvious.
    4) Replumb the whole darn thing! Sometimes, the reservoirs are plumbed as follows. Front right and back left to one reservoir with front left and back right to the other. I have also seen fronts to one reservoir and backs to the other. Personally, I would plumb it as it was in the "donor" vehicle.
    5) However, after all this you'll probably be thinkin "I shoulda gone with POWER BRAKES!!!!. That evil Ebay place is littered with inexpensive power brake boosters with matching masters. You can then hit the junk yard to find the matching swing pedal.

    Honestly, it's a heck of a lot easier to just go buy yourself a Honda, they come with power brakes right from the factory!
  4. bryan6902
    Joined: May 5, 2008
    Posts: 1,137


    You will not find a modern power booster to mount on your frame rail on your 56 Pontiac wagon so focus your energy else where. Even finding a dual master may be difficult. I switched the master to the firewall using a universal street rod pedal set-up and I have heard the pedal set-up from a 57 Chevy works also. Getting this done requires a lot of work though so maybe just rebuilding the old one isn't such a bad idea. Just my 2 cents, good luck.

  5. oldschool1956olds
    Joined: Nov 16, 2008
    Posts: 25


    does anyone out here know of any places that make a upgrade master cylinder for a 1956 olds.
  6. Chimera Motors
    Joined: Jan 27, 2015
    Posts: 1

    Chimera Motors

    Which booster/master did you end up using?
  7. Shouldn't be too hard to find something to fit in there for a firewall mounted cylinder. I once had a wrecked '66 Riviera and needed to re-do the master cylinder on my '56 F-100. Just pulled the entire pedal assembly, booster and cylinder out of the Riv and with a little modification it fit right in the Ford.
  8. Olds Dad
    Joined: Sep 22, 2011
    Posts: 216

    Olds Dad

  9. stationWAGONS
    Joined: Mar 2, 2008
    Posts: 796

    from Vegas

    I know it is an old thread, but I found it while looking for the same answer.
    Or...basically any direction to rebuild the original booster in the '56 Pontiac wagon I just got.
    (There is less help out there than with the Chevy stuff, and there are two different boosters in 1956!)

    First, I thought of But his site doesn't mention the Treadle-Vac type stuff.

    Searched...Thought about using SoutheastChevy Parts's rebuild service but who is doing the work? I kinda doubted they really had an expert in house. Like if I were to believe a chain transmission place could rebuild my ancient hydramatic...they'd have to send it to some old shop sent somewhere to get actually done.

    Then I Found:
    Ed Strain, at:

    In his website it has an endorsement from the Southeast 55-57 Chevy parts place (so they farm it all out?) and Booster Dewey saying he is the guy to do these. So I guess so!
    All routes end up with him.

    Hope this helps someone else. Took me Several odd searches to even come across him.
  10. If you decide to go with a firewall mounted M/C you might to check into this pedal assembly.

    I ordered this pedal for a customer at work for a late model GM full size van. They're not always sold as a complete assembly like this and the price seemed surprisingly tolerable. Looked like a part that might be useful for somebody's project car or truck. It includes the pedal, pad, bracket, pin and bushing as highlighted in the picture.

    GM part #25775282.

    And best of all it lists for under $50 (at least it did back in January) and can be ordered from any GM dealer. I don't have any specs or dimensions but just look under the dash of any '03 or newer full size GM van to get an idea of the layout.


    A little more info here if you need a brake lamp switch and harness...

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