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Old 07-14-2020, 01:47 AM   #21
ford38v8
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Default Re: '40 rear brake question: How snug should the drums be on the shoes?

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Originally Posted by V8COOPMAN View Post
Alan.....Read carefully! By "immediate efficiency", I alluded to the LIKELY attempt to improve front to rear brake bias by differing the size of the front/rear wheel cylinders. Ford obviously felt the need to update the brakes in '39. YOU mentioned that "Hotchkiss" brakes were less-efficient than cable brakes. Sorry to say that I'm just not familiar with the "Hotchkiss" term relative to brakes. Did you mean "Lockheed" brakes?


You also mentioned...."I have to accomplish the pressure differential with adjustments at the shoes." I don't believe that you're actually adjusting 'pressure' with this method. I believe that you are only adjusting the timing of the application of the rear shoes to be slightly later than that of the front shoes.


We own a very stock '37 coupe with the stock brakes, so I do have first-hand experience with that set-up. I agreed with you that the cables don't leak, nor do they sit there and make nasty, rusty fluid over time. My opinion though (and who cares what I think)….when reasonably-maintained, I prefer the hydraulics over the cables, especially with Bendix-types in the front and the Lockheeds in the rear. It's a combination that seems to work pretty well by default for a lot of guys, including my experience. I believe the reason that combination does work so well is that the rear Lockheeds are so marginal to begin with, both because of narrow shoe sizing and the fact that they are NON-self energizing. One thing that any of us should be careful of is oversizing or over-energizing the rear brakes.


With biasing in mind, it would be interesting to find-out whether the Ford cable brakes may have different length levers on the rears in an attempt to modulate the application of those shoes compared with the fronts. That's the only method I can imagine that would differentiate pressures derived from a single mechanical input. DD
Doggone it, I don’t know where I got locked into the name Hotchkiss while meaning Lockheed, but that’s not even the first time I made that mistake. I’m glad you know what I meant, anyway!

And in rethinking the differential of pressure thing, While a first thought would be different lengths of actuating levers, I think that approach would produce an equal pressure at first movement, but with increasing pressure on one and decreasing on the other, very soon achieving 100% pressure on the set having the longer levers. I’ll go back to my method, which effectively delays rear shoe movement, while maintaining the differential percentage from light braking through panic braking. Now you must excuse me, I’m off to gobble some aspirin.
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Old 07-14-2020, 04:50 AM   #22
51woodie
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Default Re: '40 rear brake question: How snug should the drums be on the shoes?

I Installed the Boling Bros kits on my "46, and had the same problem as my4dv8 had. Solution was the same, sand to correct the lining radius. If you look at the measurements noted in the attached picture, the thickness is reverse to what it should be; thinner mid lining than at the ends. The other problem was, the park brake cable spring was too long, and would become coil bound, preventing full travel of the arm to apply the park brake.
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File Type: jpg Left Front Lining Contact.jpg (41.0 KB, 20 views)
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File Type: pdf Brake Lining Thickness.pdf (524.0 KB, 18 views)
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