Monday, February 13, 2012

Hamilton 917 clutch lever spring fabrication

As I was disassembling the Hamilton 917 for the first time, I made the bonehead move of letting the clutch lever spring fly out....f$%k!I looked around to find that no one has the spring available, when asking vendors if a given assortment of springs would have one that would fit but no answer there either as no one can tell me. Well, looks like I am fabricating one.

Looking at the application, I figured that the wire had to be spring steel stock and any old wire simply wouldn't do. To find out what is the ideal material for this, I tried everything I had on hand from twist ties on. The twisty tie stripped easily from the casing and I decided to hammer the wire flat to fit where it needs to go. The problem is that the material work hardens easily and becomes brittle. Iteration two had me heating and quenching the wire to relive the work stress but still too brittle in the end. Next I hammer out a paperclip but with similar results as the twisty tie.

The pics of the hammered piece is for the viewer's benefit of the process and not the actual pieces used (it was 2am and I was sleep deprived) which is why the hammered piece shown is flat the wrong way. The pictures should however server to give the viewer an accurate scale of objects.

To make matters worse, I do not have any tools that would bend the wire evenly and at the ideal circumference and aperture. I measure the post on the dial that the spring wraps around and discover it to be .165mm wide, and the closest thing to the diameter on hand is a screwdriver at .160mm wide which i clamped in my vise and have been wrapping the various materials around. 3am and sleep calls....

The following day with a bit more rest, I re-approach the problem and two things are evidently clear, I don't have the proper tools or the material. Lets take look around the shop again and.....material wise I find a pack of .09 guitar strings and for tools, I went out and bought round nose pliers from AC Moore (

This time around, the guitar string despite being way thicker than the original spring (the click spring is the same and can compare it to that), but it fits and once shaped properly, is an ideal fit and better action on the clutch than the standard spring! There is a lot more tension on it but totally worth it.

I can finally happily say, suck it hamilton 917 clutch lever spring

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