A7/A10 Horns

[trevinoz]

The other day I was rebuilding an Altette horn and wondered how many different types were fitted to the A7/A10s.
I went through my pile and the Lucas book and found there were five different Altettes, HF 1441 and 8H.
One HF 1234 was used until 1948, identified by a flat back with an adjusting screw and two point mounting screws.
In 1949 a modified HF 1234 was fitted which has an indent on the back with rivets, no adjuster and no flats on the sides where the bracket fits.
In 1950 the 1949 type was modified with flats on the sides. This one was used until 1952.
In 1953, the Plunger models had the HF 1235 which is the cheap version of the HF 1234, having screws on the bezel instead of acorn nuts and painted finish, no chrome. The body was modified with a point adjuster and pole adjuster on the back, identified by a large nut and small screw.
The Swinging Arm models had the HF 1234 which had a different appearance to all previous types.
The body was as the HF 1235 described above but the front had a chromed bezel, chromed dome bolts and a corrugated tone disc.
This was fitted to all bikes until 1957 and to bikes without a nacelle until 1963.
The nacelle models had the HF 1441 fitted until about 1960 and thereafter the much smaller [and lighter] 8H was used.
There were also colour variations which I have not included.
The HF 1234 had two different brackets, depending on the bike they were fitted to. The Plunger/Rigid had a straight bracket and the Swinging Arm had a cranked bracket for the horn to clear the generator.
Hopefully I haven't confused everyone!
  Trev.

[mrshells]

Nice one Trev
but my 52 has a chrome bezel fixed with srews ?
i havnt looked but is the model number stamped on the horn some where ?

[trevinoz]

mrshells, the model number is stamped on the triangular insulator on the terminals, if you still have the original bit.
Yours looks like an HF 1235 with the bezel chromed.
The rear of your horn should be plain with a recess with two rivet heads.
After all these years and lots of rain and corrosion, it is rare to find the original horn on a bike.
Trev.

[olev]

Gday Trev,
You probably have this .. but in case you havent??
http://www.bolsover.com/lucas/sectionL7partA.pdf

for a bit of light reading as you seem to be interested in electrics, check out
the rest of the site www.bolsover.com/lucas has service sheets for maggys and generators.
cheers
 

[manosound]

Olev,

Thanks for the Bolsover post. I've seen several of these manuals, but not all in one place and not necessarily in their entirety. Knowing that websites are transient [not that I am not - question for self - will I still be riding (or breathing) at when I'm 85?] I copied all the files to my own computer, whether I needed them or not, to hold them like a child's comfort blankie.

I noticed that the electrical diagrams did not cover A7s or A10s, which is a shame, because those diagrams were quite good with respect to explaining the switch positions (our switch, but shown for a different bike.)

Richard L.

[olev]

Manosound,
for your security blankie,
Maybe your wiring diagram can be found on service sheet 808.
http://www.bsa-oc.com/modellen/service_sheets.html
Its a pity they don't have one for front forks though, which I'd love to get hold of.
cheers

[manosound]

Olev,

In fact, I've had, for some time, the A10 diagrams shown in your recommended site (quite a good site, by the way). What I liked about the diagrams for some of the other bikes was the way they detailed the action of the light switch, like the contact 1 and 7 levers, which they do not show in the A-group diagram. However, I can now extrapolate the switch details based on the drawings for other bikes.

Thanks for sharing the useful site.

Richard L.

[iansoady]

Manosound,
for your security blankie,
Maybe your wiring diagram can be found on service sheet 808.
http://www.bsa-oc.com/modellen/service_sheets.html
Its a pity they don't have one for front forks though, which I'd love to get hold of.
cheers

Just browsing through here trying to catch up and noticed this.

I have a copy of that service sheet kindly supplied by a RealClassic contributor here in the UK.

Is there somewhere on the site I can post it, or I can PM it to you if you like.

[lawnmowerman]

G'day Trev

Try Taff the Horn's website - I know it sounds like a real dodgy site but there is some real good stuff on there http://www.taffthehorns.com/

Jim

[rocket111]

Sorry to liven up an old thread ,am i correct in thinking that the 8h horn i have for my 1961 super rocket is therefore the correct one ?and should it bolt to the bottom yolk or down by the dynamo if its thee latter i guess i will have to source a bracket

[lawnmowerman]

If you mount it down by the dynamo make sure you get a cranked bracket or it will not fit. Got mine from Lyford classics.

Jim

[trevinoz]

Rocket,
               These are fitted to the nacelle type bikes and are fitted to the bottom yoke.

  Trev.

[beezermacc]

I can't get the 'bolsover' link to work, what am i doing wrong?!