MG T-ABC

I`ve been trying to get my Altette horn apart for 3 days now with soaking etc -even a little heat (throw your arms in the air) with no real success. The difficulty is removing the diaphragm. I`ve been following the description on the Triple MMM site. https://www.triple-mregister.org/upload ... ltette.pdf. It separates by about 10mm but refuses to as stated in the write up mentioned ccome out of the housing. I would add that I`ve yet to remove all of the bezel fixing studs basically due to corrosion. Is that necessary to be able to "tilt" the armature?

Having struggled with mine I would not bother again.
Rather than try and restore it, I would trade it in for a professionally rebuilt one and save hours of frustration.

I don't recall having issues taking one apart, but you might try http://taffthehorns.com/

Thank you Ray and Steve. For me part of the enjoyment of owning my cars is attempting repairs. I must admit at the moment I`ve a couple of projects that are frustrating me the horn and my attempts at plating cast iron fittings.

If the problem is the coil you are in trouble because it will not come out. I was able to get the diaphragm off by holding it in a vice and freeing off the nut. In the end I took it to my local auto electrician. Even he couldn't fix it... but he knew an old guy who could.

The altette horn is not exactly deafening which is why people replace them. The risk then is that they put far more amps through the button than it was designed for. The answer is a relay - but even there you need to take advice with the wiring.

http://www.mg-tabc.org/library/Altette_Horn.pdf

Mine had sat in a damp garage for 47 years and it came apart with no problem. It makes a huge honk, not that I ever use a horn

OK so got the diaphragm off. Mistake was not removing the bezel studs. They needed a good soak to get out and eventually did so using hydrochloric acid. Just now got to get the screws out to dismantle the contacts. There in soak.