Again folk,
this was called for on another forum....
Let me know if you want more.....
I erred to make reference to short circuits causing burned wires.... but a fuse should have prevented this.....
as posted...
Subject: Car horn not working - stumped
Hi John,
yes - mine started to work erratically and for some reason just swapping the terminals seemed to overcome this - I have an old Holden (EK) and the horns in most from FE - EK were pretty much the same .... they have a great deep loud blast in lieu of the tweet of modern vehicles......
I was pretty careful when I decided to go peek inside - I took lots of photos and marked everything so that it would go back exactly as it came apart - even to placement of individual nuts/bolts washers etc......
If yours is anything like mine - the main body will be in two parts - a base and a cover....
Within these two are a "sealed" diaphragm - this is the piece which generates sound waves.
The cover side of this diaphragm is sealed and should prevent anything entering the underside (base) where the working parts are...
There should be an adjusting screw and locknut which "sets" the stroke of the diaphragm - I have a Holden genuine workshop manual and it states the amperage on which to set this diaphragm "gap"....
Inside the base - there will be two armature "windings". These are enamel coated and should not really ever need removing or re-winding...... you can do it - but you will need to measure the induction so that they match the existing ones..... I didn't have to do this - phew!
On the underside of the diaphragm, you will find the "armature"... basically a "U" shaped metal bracket pinned to the centre of the diaprhagm.
This armature is what gets acted on by the two coils - it sort of pushes with one and pulls with the other.....
From what I have seen in the horns I have dismantled - most of the time it's crud and rust which stops them working - mainly on the contacts..
A good clean up with some fine emery (very fine) usually will get them working again - whatever you do... DON'T paint that diaphragm (I did and it "muffled" the power of the horn.... after removing the fishoilene - it is again fine)..... just clean the diaphragm up - maybe even give it a coat of wax......
The terminals (both inside and outside) are another cause for failure - there will be two bakelite or fibre washers on each side of the terminals - obviously if either of these have failed - you will either blow your horn fuse or it will sound continuously.......
You will most likely have to fabricate a sealing gasket - this was only on the underside of mine - for keeping the elements out of the electrical parts.... not the diaphragm face......
If you do make another and don't re-fit the original - it will then be necessary to "tune" or adjust the 'gap" of the armature.... your ears are probably the second best way to set this up.... you'll note (excuse pun) when it sounds correct..... if you go too far one way or the other, you will also find that it fails to sound every time it is connected..... I suppose I used the factory settings (ballpark) then fine tuned it by ear and operation.......
My suspicion with your fault - is because it has been "dunked" - that there is corrosion in the coil heads/armature area ..... along with a lot of whatever may have found its way in......
Just make absolutely sure you mark everything exactly as you pull it apart - nothing will spring out at you... I have a number of pix from when I did mine - I would have to go and find them - but they are there...... for future reference..... I'd be interested to learn of what is in the Zephyr horns, John - I would be very much surprised that there should be a lot of difference.......?
End result with mine is that it is again a great sounding horn - and a little more knowledge on how things in my old bus work ....
I went to a lot of trouble to grind out burrs, castings etc and etched, primed and multi-coated in acylic both the base and cover then blocked back and "cut and polished" to get "that" finish...... it fits in with many other little "projects" I have completed in my engine bay.......
I also drilled out all joining bolt holes to take 4mm stainless button head bolts - along with stainless mounting hex headed bolts, nuts and washers...... all these were polished on a sisal and calico buff.....
I'll post this up on the forum, John...... someone else might get something from it......
frats,
Rosco
ps - pm me if you want more - I tend to go a bit overboard (or is it "overbored") when it comes to working in the shed.........