Can anybody tell me if I can change the tone of my horn? Its a typical 6v 26-27 horn. If it is possible could I be given instructions on how to go about it? Thanks in advance. db
John Regan would be our resident expert on the subject but I just "tuned" one and I simply adjusted the small screw in after loosening the jam nut until I thought it sounded close to my other T electric horns. I'm sure there should be an electrical value associated with the adjustment so John would most likely know that answer.
Do you mean change how it sounds, or change the pitch, I.e., tune it? If you wish to change the pitch, it's normally not easy to do so, but it can be done.
I've never actually taken apart a stock T horn, but if it's similar to the other period "honking goose" horns I've worked on, this is how you would do it:
You would need to take the horn apart and either add material to the diaphragm, which will lower the pitch, or remove material, which will raise it. It's a long process of trial-and-error, but is doable.
However, you cannot weld to it, as it is made of spring steel and doing so will cause it to lose its temper. Raising the pitch will be easiest. Just take it in very small steps. No need to overdo it!
Whoops! You did mean tune it. Guess I should learn to read the titles!
I don't know if it's possible to get a pleasant sound from those dying goose horns, LOL! I know it's not right but I got an electric ahooga horn for my T.
What voltage were the 1915 horns?
The 1915 horns were powered by the magneto, so anything from probably 6V to 28V AC. They were not battery, (DC), powered horns.
I would adjust it until is puts out the loudest tone possible and a sound you like, somewhere around the middle range.. If you go too high or too low, it might not work when you need it. I adjusted mine a little on the deep tone side of the range. I too thought it was a goose horn but, the animals on the back roads have voted it to be a cow horn.
The Ford manual gives some instruction on adjusting or repairing a battery horn. It shows the adjustment points for repairs and etc.
The loudness is was I shoot for when adjusting my horn. The tone seems to be same but just not as loud when adjusting the screw shown in the diagram. Page 258 in the manual.
The original question was about a 6V 26/27 horn so I shall assume that you meant a battery horn which became available about March of 1922. This and all battery horns are in fact mechanically resonant at one frequency determined by the diaphragm, snout length, and tension on the diaghragm none of which is adjustable except by small amounts. The battery horn was adjusted for a 5 amp maximum draw from a 6 VDC source while adjusting the horn for maximum loudness. The points in those battery horns can be adjusted (unless totally screwed up which is common) so that reducing the gap will cause the horn to draw more current and increasing the gap will cause the thing to draw less current. You want to shoot for maximum loudness without exceeding 5 amps of draw.
First start by setting the gap between the end of the plunger and the diaphragm. I know - you can't see in there but you can "feel" for it. You should make sure that you cannot see any pinholes in the diaphragm from rusting due to water going into the thing. Attempting to adjust the horn with holes in its diaphragm is not going to work. There should be a lock nut holding the horn motor plunger at a specific depth. It is a 10-32 brass threaded plunger usually with a screwdriver slot in the end of it. Before you do any loosening of anything - hold the horn in one hand and with your index finger - tap on the end of the threaded plunger and you should be able to hear a "click" as the plunger hits the diaphragm from your finger force. You can tap pretty hard with your index finger and you should see the plunger return blade springs go in at the center when you tap on it. If you don't hear the "click" then somebody has over tightened the plunger already or backed it way way out. In any event you want to loosen the lock nut only enough to be able to turn the plunger to move it closer or further away from the diaphragm. If you hear the click then screw the plunger in by small amounts until the click goes away because the end of the plunger is then sitting against the diaphragm. The correct gap is 1/32" which is easy once you find the "no click" position - Simply note the position of the screwdriver slot and back the plunger out 1 full turn (its a 10-32 thread) and you will have a 1/32" gap. Lock that position and yes the darn thing will move as you attempt to tighten it but remember when you get done that the screwdriver slot should be at the position of 1 full turn out. If when you first listen for the click you don't get one then back the plunger out until you do get one when you tap on the end of the plunger then proceed back in until you just touch the diaphragm with the plunger. You need to learn to tap very very lightly as you reach the contact point and you can easily find a place at which the click just barely goes away and there is no click with even a pretty heavy tap. You can sometimes hear it better if you are an old horny listener like me by holding the snout end of the horn up to your ear as you tap on the other end. Once you set the gap to 1/32 then honk the horn and if it is loud and less than 5 amps - QUIT since most battery horns are destroyed by the point mounting frame being bent all up and screwy from too many attempt s at adjustment. Shoot for maximum loudness and forget trying to control the tone of it since that is determined by the blade springs and diaphragm as well as other housing parts. It will be resonant at one frequency and that is the max loudness point. One final point is that if your snout has holes in it or severe dings near the small end nearest the diaphragm - the horn may not honk very loud at all. I was amazed once by a horn that I was screwing with that had the right current at 4.8 amps or so but was not very loud. I happened to hold it in a way that covered a 1/8" wide "tear" in the sheet metal near the base of the snout and the thing honked louder than ever with that slot covered. You can fill any rust holes in the housing temporarily with black RTV to make it honk but longer term fix is to replace the snout - I have extras from production runs of my horns and they are made to factory drawings but you will need a spot welder to install them. You cannot fill holes in the diaphragm with anything that will work. Brazing will destroy the spring action of the thing and RTV or JBWeld messes it up too for whatever reason. I have seen both of those tried. The horn operates like a SNARE DRUM in that the perimeter is very tight and then the center vibrates. You CAN change the tone slightly by tightening the outer perimeter fasteners but that is about the only thing you can change and the affect will not be too significant.
And that's the rest of the story !
An additional bit on Richard's question: A lot of 1915's had/have aftermarket mechanical horns, I assume because the owners wanted something louder than the magneto horn or the bulb horn it replaced.
Thanks John and everyone else. I was hoping to get a deeper more goose sound out of this horn. The one I have is loud and high pitched and sounds like a girly car. Are the goosers from a particular year?
The battery horn I got from John has a nice tone, but most non-T spectators are disappointed that it isn't an aaaoogah horn!
It shouldn't be high pitched. Do you have a cracked diaphragm?
Jerry, I haven't uncovered the T to even look. I was going by the way Ed's horn sounds, in the video I made that was all about you. (OCF 2014) ~