Tuesday, February 3, 2009

Knucklehead Lightening

OK, sure, its a play on words. The original Knucklehead "Lightening cam" has pretty much passed into the realm of legend; at least among those of us old enough to remember such things. This post has only a tangential connection to those camshafts from the 1930's. It was once common knowledge that you could identify a Lightening cam by the "lightening holes" drilled in the cam gear. I am about 95% sure that was bad information. I think most of the cam gears (as well as circuit breaker drive gears and idler gears) were drilled in the same manner on all pre 1940 Harleys. Whatever the case, the idea of reducing weight to add performance is certainly a valid one.

When I first prepared to go drag racing back in the winter of 1984-85, things were still transitioning from the days when the racer did most or all of the modifications himself, to what we have now; where exotic materials are used on custom manufactured pieces to lighten the bike. I have bored many of my friends with the tale of how I had no drill press that first winter, and used a 3/8" Black & Decker electric hand drill to lighten most of the parts on that bike. I would drill holes until the drill was too hot to hold, put gloves on, and continue drilling until the drill was burning my hands through the gloves. Then I would let the drill cool off and start over. Yeah, a lot of stock parts with a lot of holes.

In the spirit of that early experience, I am approaching the build on "Vinnie", my nostalgia drag bike project, in much the same way. Nothing fancy. Just a lot of holes. Thankfully I have both a drill press and a mill to aid me now, since I doubt that anyone currently makes a hand drill that would survive the abuse like that old Black & Decker did.

Vinnie's rear wheel. Vintage rim with original spokes from my wife's '47

Vintage brake backing plate, well ventilated

New Repop hub with Repop brake drum, also well ventilated

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