Lucas Altette Car horns on A10s

[KiwiGF]

I’ve been meaning to start a thread on the Altette for a while, I’ve collected 6 cheap car horns over the last couple of years with the intent of fixing a couple of them and fitting them to my A10 and B31. I’ve finally just done this and took a few pics along the way.

Hopefully this thread will add to the info already on the site, and maybe help members search out the right car horn at swap meets etc and “convert” them (cheaply) for use on their bikes 

One thing I’ve learnt (and please feel to correct me if I get this or anything else wrong) is that by buying a chrome bezel and chrome nuts a car horn can be made into a “correct” looking horn for the A10, possibly even identical to one.

I used the “taffthehorn” web site as a source of info (tho it’s a bit of a “confusing” site I reckon) and also the Lucas service sheet.

The horns I bought appeared to be of the three types described on taffs  site, pics are below.

Type A - probably 1935 onwards and too early for an A10
Pressed steel body
Flat tuning disc
HF935 on metal tag
No “recess in body
Terminals are square
Non triangular terminal plate
2 part centre nut
External points adjuster on rear
2 screws on rear holding points assembly
No core gap adjuster nut on rear
Domed bezel (can be alloy or steel) stamped with Lucas Altette

Type B - 1938 to 1955 so probably correct for some A10s
Cast iron body
Body can have flats” on body or not
Flat alloy tuning disc
2 part centre nut
No core gap adjuster on rear
No external points adjuster on rear
Round terminals
Domed bezel (can be alloy or steel) stamped with Lucas Altette


Type C - 1953 to 1963 so probably correct for some A10s (late A10s had a different horn)
Cast iron body with flats
Points at 90 degrees to to earlier horns
Has core gap adjuster on rear
Has points adjuster on rear
Has 1 part centre nut
Has flat sided terminals
“Flat” bezel only in steel with no stamping of “Lucas Altette”
“Rippled” tone disc

[KiwiGF]

These show the “flat” bezel with “rippled” tone disc.....

[KiwiGF]

Here are the two horns I fixed and fitted, only one was marked HF 1235 but I think all the type B and C I bought were HF 1245s. HF 1234s are chrome versions of the 1235.

I was lucky to find under the black paint that I’d bought two horns with alloy bezels, which polish up very easily, and are (I think) a “correct” horn option for bikes. I’ve read Lucas supplied these instead of chrome horns at times of shortage of nickel/chrome after WW2, well I hope that’s the case as I’m not forking out for a chromed bezel! The alloy bezel horns should probably have fancy nuts on the bezel instead of screws and if so I might update them later.

Being car horns they are 12v rated, the horn fitted to the bike with 6v sounds weak, but I’ll probably alter the 6v bike to 12v at some point. I’ve still got 4 horns to experiment with.

I’d be interested in how to rewind the coil for 6v if anyone knows how? A Vincent site seems to say 76 turns of 24swg copper will do it but I’m not sure that’s right.

As far as fixing the horns, all 6 had points that had corroded and caused them not to work, this was fixed by cleaning with 400 grit sand paper.

In respect of adjustment, I did the core gap first, I used a dial gauge and found 015 made the best sounding vibration, 020 as per the Lucas manual did not work well at all, I did this without the tone disc or bezel fitted, just 4 screws holding the diaghram.

The push rod adjustment is next to be done, I did not follow the Lucas instructions and used the external adjustment to make the contact assembly “level” with the body, and then adjusted the push rod to just touch the points.

The final adjustment is using the external adjuster screw with everything altogether. I found it needed screwing in clockwise less than quarter of a turn to give the best tone.

I used type “C” horns as these are the easiest to adjust, the type “A” has the core gap adjusted using gaskets of different thickness, the type “B” also requires messing with gaskets to get core gap right, it also does not have an external adjustment screw and using the push rod adjustment to get the tone right is quite tricky to do.

[JulianS]

Lots more interesting Altette information here;

http://taffthehorns.com/

[Greybeard]

I pimped up the Altette horn that came with my bike by getting the bezel chromed. I used ready plated dome nuts from a hardware store. Looks ok. Not sure which model the horn is. It has an adjuster on the back.

[KiwiGF]

I pimped up the Altette horn that came with my bike by getting the bezel chromed. I used ready plated dome nuts from a hardware store. Looks ok. Not sure which model the horn is. It has an adjuster on the back.

As far as I can tell if it has an adjuster screw on the back it’s a (1930s) type “A” or later type “C”. It’s more likely to be a type “C”, which will have “flats” on the body.

The plated dome nuts are a good idea, did you have to fit studs instead of screws first?

[LJ.]

Lovely things, my 1953 B33 has one, has a heck of a beep to it and is 6 volt. I just don't know what the finish is...if its worn down chrome or some kind of plated coating. Heavy old things!

[Greybeard]

I pimped up the Altette horn that came with my bike by getting the bezel chromed. I used ready plated dome nuts from a hardware store. Looks ok. Not sure which model the horn is. It has an adjuster on the back.

As far as I can tell if it has an adjuster screw on the back it’s a (1930s) type “A” or later type “C”. It’s more likely to be a type “C”, which will have “flats” on the body.

The plated dome nuts are a good idea, did you have to fit studs instead of screws first?

The plating is not as bright as chrome. I guess I must have changed the stud part to suit the metric dome nuts; can't quite remember.

[Bsareg]

Ive done a few of my altette horns by removing the studs and screwing metric socket mushroom screws from the rear to allow cheap stainless metric dome nuts instead of the acorn nuts. Retap a stainless 10mm dome nut for the centre and the jobs a goodun, only a rivet counter will notice .....

[KiwiGF]

Lovely things, my 1953 B33 has one, has a heck of a beep to it and is 6 volt. I just don't know what the finish is...if its worn down chrome or some kind of plated coating. Heavy old things!

What’s odd is that, according to the info. on taffthehorn site, both the type B and C horns were “correct” for the overlapping years of 1953 to 1955, your bike has a type C which is consistent with that info.

Another snippet of info is that bezels of type C were not marked “Lucas Altette” as BSA did not want that on the horns, however, if a aftermarket/replacement type C horn was bought, it would be stamped with Lucas branding........could be urban myth of course!

[KiwiGF]

I pimped up the Altette horn that came with my bike by getting the bezel chromed. I used ready plated dome nuts from a hardware store. Looks ok. Not sure which model the horn is. It has an adjuster on the back.

As far as I can tell if it has an adjuster screw on the back it’s a (1930s) type “A” or later type “C”. It’s more likely to be a type “C”, which will have “flats” on the body.

The plated dome nuts are a good idea, did you have to fit studs instead of screws first?

The plating is not as bright as chrome. I guess I must have changed the stud part to suit the metric dome nuts; can't quite remember.

Yours is type C, but with Lucas stamped on it, so (alledgedly) not what BSA fitted, but it could be a period replacement, or one of taffs bezels.

Personally I prefer the bezels to be branded Lucas!

[Slymo]

Ha! Just done exactly this except I rewound the coil so that it was 6v rather than 12v. Very simple in that you unwind the coil fold in half and solder the conection onto the middle and then the two remaining ends together, so twice the thickness but half the length. I did this with an aluminium bezel version for my bitsa RE Bullet with great succes some years back. With a Super Rocket one I got the wavy centred horn with the steel bezel. Made new dome headed ba screws for the rim and have them and the bezel off at the platers now.

[LJ.]

Lovely things, my 1953 B33 has one, has a heck of a beep to it and is 6 volt. I just don't know what the finish is...if its worn down chrome or some kind of plated coating. Heavy old things!

What’s odd is that, according to the info. on taffthehorn site, both the type B and C horns were “correct” for the overlapping years of 1953 to 1955, your bike has a type C which is consistent with that info.

Another snippet of info is that bezels of type C were not marked “Lucas Altette” as BSA did not want that on the horns, however, if a aftermarket/replacement type C horn was bought, it would be stamped with Lucas branding........could be urban myth of course!

Excellent info and very interesting reading.... thanks for that KiwiGF, you've certainly gone deep into research on this.

[KiwiGF]

Ha! Just done exactly this except I rewound the coil so that it was 6v rather than 12v. Very simple in that you unwind the coil fold in half and solder the conection onto the middle and then the two remaining ends together, so twice the thickness but half the length. I did this with an aluminium bezel version for my bitsa RE Bullet with great succes some years back. With a Super Rocket one I got the wavy centred horn with the steel bezel. Made new dome headed ba screws for the rim and have them and the bezel off at the platers now.

Thanks that answered my earlier question, I wondered if it was as simple as half the turns and double 5he current 

[KiwiGF]

Lovely things, my 1953 B33 has one, has a heck of a beep to it and is 6 volt. I just don't know what the finish is...if its worn down chrome or some kind of plated coating. Heavy old things!

What’s odd is that, according to the info. on taffthehorn site, both the type B and C horns were “correct” for the overlapping years of 1953 to 1955, your bike has a type C which is consistent with that info.

Another snippet of info is that bezels of type C were not marked “Lucas Altette” as BSA did not want that on the horns, however, if a aftermarket/replacement type C horn was bought, it would be stamped with Lucas branding........could be urban myth of course!

Excellent info and very interesting reading.... thanks for that KiwiGF, you've certainly gone deep into research on this.

Thanks, what actually prompted me to do a bit of a write up was that despite the comprehensive info on taffthehorn site I did not see a clear statement there that it’s possible (for A10s) to take a common car horn and “convert” it into a bike horn by chroming the bezel and fitting dome nuts, if this was generally known it would not be good for his Altette horn supply business maybe 

The car version (hf1235) of the Altette found on A10s is pretty common and so should be available cheaply in scrap yards etc, cars like Morris minors and some minis had them I think, and probably lots of other cars of that era. Some of the cars were 6v but you’d be lucky to find a 6v horn.