I grew up around a shop where we arc-ground brake linings. Most brake linings come from the factory with the radius of the shoes matched to the size of a standard-diameter brake drum. When the durms are machined oversize during routine brake maintenance, the linings are no longer a perfect fit to the radius of the drum. The contour of the lining is ground to the correct fit with the drum so there will be a correct fit and maximim contact between the lining and the surface of the drum. Otherwise, the lining must "wear-in" before there's a correct fit between the mating parts.

Now, here comes the tricky part- - - -the lining is not ground to the exact radius of the drum. It must be ground so the initial point of contact is at the center of the shoe. As the drum distorts slightly from the pressure of the wheel cylinder, the toe and heel of the brake lining comes into full contact with the drum, giving the most effective lining to drum fit.
Jerry



"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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