1965 Corvette Horns

[Jerry DiTullio]

Hi,
Is there a way to adjust the sounds of the horns? I noticed there is a screw on each horn. Are they used to adjust the sound? Thanks

[Jack H.]

Re: 1965 Corvette Horns

The adjusters, fine tune the horn's volume (output). If you want/need to adjust the frequency (tone), that means opening the horn and adding/removing mass at the vibrating diaphram.

That's one of the 'featured' services of Dennis Portka during his horn restorations. His belief (right or wrong) is you never know when you might run into a judge with a musical background and an ear for perfect pitch.... Hence, he claims he test honks each horn using a special clamping fixture and 'trims' each diaphram to put it on pitch prior to the final riveting assembly....

[Joe C.]

Re: 1965 Corvette Horns

Jerry,

The limit screw that you refer to adjusts the amplitude of the diaphragm's travel between it, and the fixed, energized contactor. By turning the screw clockwise, you will decrease the amplitude, and thus, increase the frequency of the vibration. This adjustment has a very narrow band of tolerance, and will noticeably affect the pitch/loudness of each unit. Once out of that desired band, horn operation will abruptly stop. The horn(s) is(are) designed to operate within a very narrow sweet spot, based on the aforementioned weight/flexibility of each diaphragm. The most important consideration, bar none, when assembling a horn assembly, is absolute flatness of both "cochlea" halves. Clamping force of each rivet must be consistent, also.
One very, very problematic area, is continuity between the positive lug, its rivet, and the conductor within the housing.
If your internal components are serviceable, then adjustment for max volume should also yield proper tone.

Joe