Original Horn ID and operation questions Options

[Literati914]

While reassembling my ‘72 project it’s come time to figure out my horn situation. I found these two horns in a box and am not sure if one or both were original to the ‘72. My car does have the wiring for two horns but I can not remember if both of these were on it before disassembly. I kind of think the smaller one was on my ‘74 parts car.

Either way, I need to know: are these two normally used in conjunction with one another as low/high (quiet/loud (IMG:style_emoticons/default/biggrin.gif) ) - if that can even be determined without part #s? If they are both of the same volume I guess I’d just be using one - or do two quiet ones make a loud (IMG:style_emoticons/default/confused24.gif) Are there any knowledgeable horn experts that can help? Thanks

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[technicalninja]

I've brought old horns back to life by submerging them in WD/40, letting sit a couple of days.
I'll then go nuts with the blow gun and the needle tip...

Try them again, lather rinse repeat.

Slap them around while applying power.

I saved many this way (not a single Porsche yet!).

All of the ones I have come across (mostly Japanese sportscars) were riveted and could not be dissembled easily.

I have saved some German ones (Bosch?) but they were BMW/Mercedes.

It's really just like johnhora posted, just clean them up!

As for polarity I'd first check if either of the posts have continuity to the horn case.
If one does, I'd put the ground on that one.
If one has continuity the other side will as well but it will show the resistance of the coil and its reading will be different than the other.
Lowest resistance to case gets ground.
Both not have continuity?
I'd try it both ways and use what sounds best.

I'll look to my stock 75 and see how Porsche did it and report back.