Wednesday 19 August 2009

The Model 18 cranckshaft

Picked up the 1928 Model 18 cranckshaft yesterday. A new big end from Alpha Bearings was fitted, a new small end was made, and at the same time the opportunity was taken to dynamically balance the cranckshaft. While the Norton factory certainly did a very good job in the 1920s, things have improved; Bob van der Zijden uses decades of experience and computer-assisted equipment to spin the cranck and measure the unbalance. In the case of my cranck, 15 and 20 grams were removed from respectively the left- and right-hand side of the cranck; which apparently is still quite a lot on a cranck that weighs in at 13 kilo's; you can see the two holes that were drilled to remove metal close to the bigend-nut. This should result in much less vibration, higher revs and increased speed!