MTFCA Forum

Thanks to youse guys, the friend's 1925 horn under discussion in the last few days has been fixed and mounted back on the engine. The horn sounds great! To my pleasant surprise, the horn button on the steering column is functional! I was expecting a bare knuckles fist fight there, too. Whew! One less headache for me to deal with.
Headache #2 is on the horizon, however, with a second horn. This horn is mine and I've owned it for a couple years. Unlike Horn #1, this one is set for a '26-27, judging by its bracket. The mechanism differs from Horn #1, as you can see in the photos below, if you compare them to the views posted in the earlier discussion. The horn's innards are quite rusty, but I hope salvageable. Of course, it doesn't work right now. SURPRISE!!! That's what I'd like to correct. After all, we're on a roll here with one Model T horn diagnosed and fixed. Let's try for two!
Is there an electrical cleaner chemical I can spray all over the little motor that will make the rust come off without damaging the delicate coil, wiring and other small parts that make the motor go? I'd prefer not to completely disassemble the poor thing for fear that it won't go back together properly. The points are stuck together, so that part of the horn will definitely need to come apart. Any other recommendations that would help make this horn a horn again?
As always, T.I.A. (I'm too lazy to type out "Thanks In Advance". Ha, ha, ha!)
ADDED: Just to be clear, my question in this posting is directed more towards how to clean up the motor and parts rather than how to make it functional again. All the excellent advice posted in the earlier discussion will take care of that nicely.
Marshall

Horn shown in the pictures is a pre 1926-27 horn.

Some light wire brushing, being careful to NOT touch the coils may be all you need. Like maybe a small wire wheel on a Dremel tool. You can focus on small areas and have good control that way.

I see 2 potential problems. The coil shown on the left in photo #2, appears to have gotten very hot at one time. Insulation is burned off towards the top of the coil. Also, what can be seen of the diaphragm shows that it's very rusty and I believe I also see a crack in it, which is not too uncommon. Rust can be sanded off, but lots of times, there are holes rusted through. Cracks & holes require a new diaphragm. Given the overall condition of this one, you should probably replace the gaskets as well. Either way, to clean it properly, the diaphragm needs to come out. You'll have to drill out a few rivets to disassemble it.

"Horn shown in the pictures is a pre 1926-27 horn."
It appears then that someone put a '26-27 bracket on the horn to mount it underneath the coil box on the engine, where it was moved in 1926. Even being an earlier horn, I assume the operating principles are the same my friend's horn?
Marshall

... .- ...- . / --- ..- .-. / -.-. .-.. ..- -...

Marshall, the 26-27 horn bracket mounts to the engine using 2 bolts on the water inlet. The horn bracket in your picture, a pre 26-27 style, mounts to the engine with one bolt at the water inlet and one head bolt. The battery horns themselves are the same over the years but there were some differences from one manufacturer to another.

Yup! Right you both are! I just went down to the basement and looked at the mounting bracket again - it is the pre-1926 style. 'Don't know how I messed that one up! My mistake. So, the horn AND bracket are the earlier design. Thanks.
Moving forward...
M.

Any progress?

"Any progress?"

Unfortunately not. Other Model A and T repair work will have to take precedence and be attended to first. I think this rusty horn project will have to be an "as time allows" kind of deal now, especially since it will require so much tedious cleaning of tight and delicate areas on the horn's motor. It will after all be necessary to drill out rivets and disassemble the whole shooting match to do a thorough job, I fear. Well, I'll learn a new Model T skill by the time I see light at the end of the tunnel and hear the familiar goose honk from this puppy.
Marshall