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Project Plymouth gets a decades-old brake trick…
Drilled Drums
Text by Dave Hill / Photos by Jerry Weesner and Dave Hill
What's the first thing you think of when considering updating your '50s cars brakes? Discs of course. There are many ways of adapting discs these days, the easiest of which is ordering a kit from one of our advertisers. But what if nobody makes one for your car? If you are building a mid-'5Os Mopar, I can assure that such is the case. It certainly is with my '55 Plymouth wagon, and I'd bet with any year Nash, Hudson, Kaiser, Packard, or similar orphan. After calling around and searching the web, I resigned myself to a lot of custom fabrication and junkyard searching. Then I remembered a guy I'd met on the Internet with a '55 Plymouth powered by a 440 Mopar. What had he done for binders? Bob McGee at My55rock@aol.com likes to help out fellow '50s Mopar fans, and turned me on to C.H. Topping in Long Beach, California, where he had his '55 drums drilled. I checked out Topping's web site (www.chtopping.com) and learned all about drilling holes in brake drums. When I called, I talked Vince Bunting, who gave me the whole scoop.The company was founded in 1931 by C.H. Topping to sell auto parts. Topping later learned the drilling trick from a fellow named Mel Hamer, who came up with ventilatedif he drilled some holes in his brake drums the heat would escape and the car would stop better. It worked so well, that all the other racers wanted him to do theirs also. Apparently this became a well-kept secret, as nobody I mentioned the technique to had ever heard of it. It was while he was working with Bill Stroppe on various Ford race car projects that a production car engineer told Hamer drilled drums would never work near as well as the new disc brakes they were then developing. Bunting figures that comment led to the reason Detroit never produced ventilated drums and why the rest of us know nothing about them.The first question people ask is about water and dust. If you've driven a drum brake equipped car through water you know braking is non-existent. With holes in the drums, centrifugal force not only evacuates dust, but water immediately as well. But the main benefit is the fact that when drums are vented properly, so as to eliminate balance and material integrity problems, they virtually eliminate fade, which is.the primary reason discs replaced brakes while racing at the dry lakes. He figured drums in the first place. Gasses are vented as well, as the holes create what amounts to a venturi effect, venting gases created by compression of air between the shoes and drum that would otherwise be trapped in a stock, unvented drum, hindering braking efficiency. This also holds true with disc brakes (believe it or not), so venting is beneficial here, too.
Another benefit is reduced unsprung weight, which improves ride quality. Surprisingly, a brake disc weighs three times what a drum does, and calipers are four times heavier than a wheel cylinder. Cars designed with discs take all those extra pounds (approximately 60 total) into consideration in their suspension system. Therefore, adding discs to the Plymouth would likely roughen up the ride quite a bit if I didn't change the springs and shock absorbers to compensate for the extra pounds.
I can't think of an easier, less expensive way to upgrade your stock brakes. All you have to do is box up your drums and send them to C.H. Topping. They will have them back to you in just a couple of days. It would be a good idea to have them checked for cracks or excessive wear first. They also supply a wide variety of master cylinders, including the modern dual chamber model I decided to replace my stock one with. Oh, they will also ventilate disc brakes, if you are already so equipped. Give them a call for more info.
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