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Technical Drum Brakes

Discussion in 'Traditional Hot Rods' started by bridger, Sep 12, 2013.

  1. bridger
    Joined: May 15, 2008
    Posts: 57


    i have 39-48 ford master cylinder ,where the brake line comes out of the cylinder should there be a adjustable proportining valve where it tees of to the front and back ? i cant quiet make it out on all the old diagrams i have found on the net . And what size tube should be used with drums ?
  2. 1wrench
    Joined: Oct 20, 2012
    Posts: 30

    from Michigan

    Just did lines on a '63 e100 truck. Drums around. The lines were 3/16" there were 2 ports on the m/c and the front wheel cylinders and rear cylinders have different bore sizes. That's how they are proportioning the bias. Don't know if your setup is the same

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  3. Try these diagrams:

    and no, as you can see there should not be an adjustable proportioning valve if you are talking about a stock system.

    The original system used 1/4 inch brake lines (and it worked fine) and I suggest you stay with that size to make it easier to find fittings.

    Most parts are available from local parts houses or the antique Ford parts suppliers. Two sources tat specialize in the early Ford brakes are: Richard Lacy at, (626) 338-2282, Dennis Cling at

    Charlie Stephens
    Last edited: Sep 12, 2013
  4. 40FordGuy
    Joined: Mar 24, 2008
    Posts: 2,908


    There is a residual check valve in the master cyl, but proportioning valves didn't begin to show up until the dual systems, circa 1967.

    Wheel cyl bore sizes; Ford wheel cyls (39 thru 48) have 2 different bore sizes in each cyl. The "larger" size operates the forward facing (primary) shoe, and the "smaller" bore operates the rear facing (secondary) shoe. Because of the way the lines connect, there are left and right wheel cyls.

    This is with the factory stock brake systems.

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  5. bridger
    Joined: May 15, 2008
    Posts: 57


    Thankyou all for your advice

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