Horns?

[f1fascination]

Hi all, has anyone stripped apart the Fiamm horns on their 105 series?
I have stripped them down for refurb but on reassembly all I get is a "thunk, thunk" sound when I power them up. I understand the magnetic field between the coils causes the disc to vibrate, but there is a selection of spacers and washers between the disc and the part that sits between the coils, the "hammer" I believe, and I'm sure I've just botched the reassembly process.
Has anyone seen a diagram or knows what goes where?
I know that new style Fiamm horns are regularly available but I would like to keep my originals if I can get them working!

[colcol]

About twenty years ago, i had the Fiamm horns stop working in the 33, so one Sunday with nothing better to do, i pulled them apart and cleaned them up, and upon reassembly, couldn't get them to work, and got the thunk-thunk sound you talk about.
There is an adjustment screw, but that made no difference, after a few hours stuffing around, i went to K-Mart and purchased some replacement Fiamms, they were the same!.
You may wish to purchase some new ones and put the new insides on the old shells, so they look the same, Colin.

[f1fascination]

That sounds like a great idea. I fluffed around with them for about an hour on the bench, using a jump pack to power them up, but to no avail.
I think I'll shout the old girl a new set.
Cheers!

[Cool Jesus]

Is it a membrane that is pulsated inside the casing?

[cjheath]

I think it's a traditional Klaxon type, which means it should have an adjustment screw. I can't check mine right now, but the adjustment has to be within a fairly tight range - any disassembly will change the dimensions slightly and will require careful re-adjustment. When the horn is first powered, the "click" should de-activate a contact that removes the current, and if that happens *with the right timing* then the horn will sound, otherwise it'll just click-on, click-off.