MTFCA Forum

I've taken several apart. They're not that complicated. Maybe you can fix it. What have you got to lose?

I confess that I have not taken it apart as I do not have a clue what to look for and have never attempted to. When the horn button is pressed, I just hear a mild click. I have checked all the connections but that is all.

Horns need adjustment and cleaning every so often

I will take it apart; what do you suggest I look for?

Dan

SurveyKing wrote: ↑

Tue Nov 19, 2024 11:45 am

I will take it apart; what do you suggest I look for?

Dan

There have been several threads on this forum pertaining to horn repair. A search for them may prove very helpful. Past that, post photos of your disassembled horn in the Discussion thread. As for disassembly, right now, just remove the back cover and show us what's inside.

Here is one such thread you can check out... viewtopic.php?f=2&t=33972&p=263505&hili ... rn#p263505

Since battery horns have a set of points that can arc and pit, thus needing more frequent adjustment, is there any benefit to putting a small condensor on the points? Hey, I'm a doc, not an electrician!

Jerry,
I am posting two photos of the interior of the horn. When I depress the horn button, the diaphram at the back does move a little but no sound, just a suttle click.

Thanks in advance for any help.

Sorry, I don’t know how to move the thread, but it’s pretty straightforward in there.
Try tapping on the set screw that emerges from the top of that coil with your finger, there is a center pole and that bob weight in there that should bounce a tiny bit and hit the diaphragm like a drum. Loosen the nut and adjust the set screw in and out a bit while testing. Resetting the point gap by loosening the two small screws and sliding the little mounting bracket is necessary if the points are reduced in thickness by wear. Which could be the ticket. It’s too blurry to see in there but if the points are angled, oxidized, pitted or otherwise crusted up, it stops making good contact and the coil does not energize fully and pull hard enough. Start by checking the wiring all the way up to the switch and back, and clean all the connections. Be sure that the squiggly wire from the coil is well insulated by the phenolic washers where it attaches and not touching the cover, as the ground for the whole system is through the horn body mounting to the engine. Make sure there is a good ground through the other mounting screws if the horn body was repainted.
Run a folded piece of fine sandpaper between the points and then clean well with alcohol or brake cleaner, and compressed air. An emory board or point file is kinda too thick and could rebend the small spring with the point in it. If it’s on the bench it will croak but it’s best to adjust that set screw on the car for the best sound. Volume will depend on how well it’s working as much as any adjustment but the tone is usually different on and off the car. It’s possible that your horn button is to blame for poor contact as well, so clean the contacts in there and check the connections and wiring. If it slowly stopped working the culprit is likely too much gap in the points, which does get fussy. Try to keep the set screw in the same place if you adjust the points then move it once they are making good contact again. I had to replace the points in mine as they were too thin for the adjustment to handle the spacing. I never found a specific gap for the points but there should be some light between them when the plunger is pulled toward the diaphragm. That gap will (sort of) adjust the frequency so there is a balance between the point spacing and the total travel that you have to find. You’ll notice the plunger has a tab that hangs off and pushes the springy point away from the solid mounted point and creates the gap, thus breaking the circuit and allowing the plunger to return and close the points again.
I added a small capacitor (with a rating close to 50/50) as I feel like any rapid on off circuit like this benefits from the small amount of current that stays available to help it restart and reduce wear by eliminating (mostly) any arcing.
Sorry if this seems long winded and difficult but after the first time it will make sense and I suspect you will fix it easier than it might seem now. Let me know if you can’t get it though, I will happily send mine down and rebuild yours as my car will be off the road for the winter anyway. Good luck and continue to let us know how it’s going! -Chris, in Boulder

Great write up, Chris!!

Chris, Thank you for that great dissertation on Horn repair! We are now departing on a ten day trip so will work on this upon my return and let you know. It is great to have such kind people on this forum. Will give you a shout out in a couple of weeks.

Dan

Chris, I pretty much did all what you suggested. Then I removed the Horn and took it to Julius Neunhoffer where he tested it and found the horn itself operates as it should when connected straight to a 6 volt battery. Mounting on my car and closing the horn switch I only get 2.5 volts which is too low to operate the horn. Checking both wires at the connection points on the horn switch I get 6+ volts, but closing the switch causes it to drop to 2.5. Any suggestions here? email me through the forum or call me. Thanks my friend.

Troubleshooting the switch mechanism and checking out the wiring is underway. Horn operates as should… Go Dan!