Ask Dave: Clanking Parts and the Valve Levers

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Bruce B. asks:  

Following up on your article on clanking valves. My horn (Holton 179, early 90s vintage) will clank if I am careless about adjusting the string position relative to the valve rotor.  If I adjust the string so that the finger lever is positioned close to the lead pipe, the back end of that finger lever can strike the tubing near the valve cluster.  Clank!  The solution is to adjust the string so that the finger lever is relatively high — away from the lead pipe.

Dave replies:  

Your note is about clanking parts, but it brings up a point about lever positioning. Some horns have very little tolerance for adjusting the lever height by only using the string set screw on the rotor stop.  If the height of the levers in unacceptable in this small range, then you’re only option is to modify the levers.

I don’t recommend taking a pliers and just bending them.  You can mar the surface of the lever paddles pretty badly.  And, you could possibly break the lever paddles.

Instead, take the horn to your technician and decide the best way to modify the levers.  Bending them down might be just the right thing, but your technician can do it without marring the metal.  And, if there is a problem then the technician is equipped to handle it.

And, while you have the levers off the horn it would be a good time to make sure everything about your grip and the geometry of the levers is correct.  Your technician should check the positioning of the lever arms against the rotor stop.  Even factory made levers are sometimes not bent exactly right.

The lever should be positioned so that the string does not “saw” against itself throughout the down stroke.  And the lever arm should be close to, but not touching, the rotor stop with enough clearance to allow the string to go around the rotor stop in both directions without touching the arm.

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