| Steve S | -- 03-17-2010 @ 3:49 PM |
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I just bought a set of replacement shoes for my '39 pickup. The pads that came out were as the book shows - two long pads and two short pads. The replacements I was sold are all four "medium" length. The guy who sold them to me, who runs a respectable lining shop, swore up and down that it wouldn't matter and I would notice no difference. Any thoughts on whether or not he's right about that? Obviously I want the brakes to work as well as possible, especially with my wife driving the thing.
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| tudorbilll | -- 03-17-2010 @ 4:31 PM |
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I,d be more concerned he has the right lineing.I think its a little softer. LETS GET SOME MORE COMENT
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| Steve S | -- 03-17-2010 @ 5:24 PM |
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I had another thought... I also gave up what I believe are original '39 brake shoes for a set of aftermarket ones. Did I make a mistake? It isn't too late to go back and make him reline the original shoes. The aftermarket ones he gave me are slightly more sturdy if that matters.
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| supereal | -- 03-18-2010 @ 8:57 AM |
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The brakes have a long (primary) shoe toward the front, and a short (reverse) show facing to the rear. We often find them reversed. The configuration is to put the maximum force of braking onto the anchor, not the wheel cylinder. Be wary of "one size fits all" linings, as they are often made of very hard materials that reduce braking power. When asbestos was banned from brake linings and clutch facings, the substitute materials often were inferior. Mechanical brakes suffered the most when woven linings became scarce.
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| Steve S | -- 03-18-2010 @ 9:38 AM |
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Thanks, that makes sense. Assuming the pad material is correct, should I be concerned with the four identical pads?
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| supereal | -- 03-18-2010 @ 9:56 AM |
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I wouldn't worry too much. As said, the composition of the linings is most important. If you find that the braking is poor, I'd change them. Most of us don't drive our cars at high speeds. If you do, I'd practice a few panic stops just to be sure you can do it if necessary.
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| Steve S | -- 03-18-2010 @ 10:12 AM |
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I don't have any point of reference, as this is my first truck of this type! It will be some time before it's running anyway... On a related note, does anyone know how far the brake drums can be turned? I can't find it in any manual.
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| supereal | -- 03-19-2010 @ 7:38 AM |
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Standard diameter is 12". The "book" says not to turn them more than .060
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| jerry.grayson | -- 03-19-2010 @ 10:44 AM |
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The secondary shoe does not matter much, but the primary shoe does most of the braking and I would want it to be as long as possible. It sounds like your parts guy does not understand how early Ford brakes work.
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| Steve S | -- 03-19-2010 @ 11:33 AM |
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That makes sense, and I just called my lining shop about it. He tells me that earlier models used the long/short configuration and that my '39 should have them all the same length. I don't have a clue if he's right or not. Perhaps I'm mistaken in my thinking, but a shorter pad may grab harder since it's the same pressure being applied but over a smaller surface area?
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| supereal | -- 03-19-2010 @ 12:11 PM |
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The long/short configuation was used thru 1948. As Ford didn't use hydraulic brakes until 1939, I don't know why "earlier models" would apply. I'm not a brake engineer, but brakes should be applied evenly, not grab. As the system pressure increased, it is fair to assume that the secondary (short) shoe would come into play. One of the main drawbacks of drum brakes is "fade", caused by heat. It follows that longer lining create less heat than short one due to differences in surface area.
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| Pauls39 | -- 03-19-2010 @ 6:20 PM |
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Your 39 brakes are not truely self energizing like the later Ford brakes. The larger pad on the forward shoe does much of the braking when you are going forward. Sound like your brake guy dosen't understand these brakes. I would recommend using the original type of shoes, larger pad forward smaller pad on the opposite shoe.
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| supereal | -- 03-21-2010 @ 10:48 AM |
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The early hydraulic brakes were "Lockheed". The later, '49 and up, are "Bendix" type.
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