The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: KiwiGF on 11.08. 2018 07:01

Title: Lucas Altette Car horns on A10s
Post by: KiwiGF on 11.08. 2018 07:01
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  *smile*

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




Title: Re: Lucas Altette Car horns on A10s
Post by: KiwiGF on 11.08. 2018 08:08
These show the “flat” bezel with “rippled” tone disc.....

Title: Re: Lucas Altette Car horns on A10s
Post by: KiwiGF on 11.08. 2018 08:41
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.






Title: Re: Lucas Altette Car horns on A10s
Post by: JulianS on 11.08. 2018 09:42
Lots more interesting Altette information here;

http://taffthehorns.com/
Title: Re: Lucas Altette Car horns on A10s
Post by: Greybeard on 11.08. 2018 09:48
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.
Title: Re: Lucas Altette Car horns on A10s
Post by: KiwiGF on 11.08. 2018 12:46
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?
Title: Re: Lucas Altette Car horns on A10s
Post by: LJ. on 11.08. 2018 13:20
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!
Title: Re: Lucas Altette Car horns on A10s
Post by: Greybeard on 11.08. 2018 15:10
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.
Title: Re: Lucas Altette Car horns on A10s
Post by: Bsareg on 11.08. 2018 18:00
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 .....
Title: Re: Lucas Altette Car horns on A10s
Post by: KiwiGF on 11.08. 2018 22:58
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!





Title: Re: Lucas Altette Car horns on A10s
Post by: KiwiGF on 11.08. 2018 23:03
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!
Title: Re: Lucas Altette Car horns on A10s
Post by: Slymo on 12.08. 2018 08:07
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.
Title: Re: Lucas Altette Car horns on A10s
Post by: LJ. on 12.08. 2018 11:41
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.
Title: Re: Lucas Altette Car horns on A10s
Post by: KiwiGF on 13.08. 2018 05:26
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  ;)
Title: Re: Lucas Altette Car horns on A10s
Post by: KiwiGF on 13.08. 2018 05:40
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.
Title: Re: Lucas Altette Car horns on A10s
Post by: KiwiGF on 13.08. 2018 05:45
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.

Out of interest is this method of rewinding only easy on the horns with a core gap adjustment on the rear? The coil on those horns without adjustment appear to held in place by a pressed on washer that looks tricky to remove.
Title: Re: Lucas Altette Car horns on A10s
Post by: Slymo on 13.08. 2018 06:54
I think the days of cheap Altettes from the wreckers are long gone. I ravaged my older bro’s supply for mine.
Title: Re: Lucas Altette Car horns on A10s
Post by: trevinoz on 15.08. 2018 22:54
A six volt coil has sixty turns of 0.8mm wire, I have made many of them over the years. This is for the type C but works equally well for the others.
The type B had 68 turns of a lighter gauge.
The armature movement should be in the order of , I think, 0.011" to 0.013".
It varies with the condition of the diaphragm, some work very well with 0.010"
Some trivia, the type B which was introduced for 1949 had a round body for that year only but had the flats the next year.
Title: Re: Lucas Altette Car horns on A10s
Post by: trevinoz on 16.08. 2018 02:38
Further to this on re-reading the first post.
The cast iron body was first used in 1949.
From 1937 - 48 the body was cast iron with 3 screws on the back, 2 for the points mount & 1 for points adjustment.
They were all HF 1234/1235 regardless of the body type.
I don't think that the alloy bezel was used on motorcycle horns though plenty are there now, I have never seen an original 6v horn so fitted, only 12V.
The wire gauge on the early horns winding was 0.6mm, 68 turns.
To rewind, the points have to be removed, easy on the pressed steel body but rivets have to be drilled out on the others.
To get at the winding the retainer must be butchered out, brass on early, aluminium on late.
The horns up to about 1946 had the winding encapsulated so must be chopped out.
I fit the new winding and seal it in position with RTV compound, usually non acidic.
I think that the horn with the rear pole adjuster was first used in 1952.
These are the easiest to get working, no need for multiple gaskets under the diaphragm.
Title: Re: Lucas Altette Car horns on A10s
Post by: cyclobutch on 16.08. 2018 11:29
I picked up a good looking and original Altette from ebay a couple of years back. All still with nicely chromed furniture. I must have lucked in as it really wasn't much money.

It turned up with connecting wires still attached but clipped an inch and a half or so away from the connectors. Left me with the horrible feeling that maybe the vendor had just half inched it from someone else's machine. It's quite out me off ever fitting it.

I have a certain paranoia for leaving my bike in the same place twice for fear someone would steal the clock - mine is on the cafe racers style plate mounted on the top fork nut. I guess after the speedo the horn is then best highest value and easiest thing to remove.
Title: Re: Lucas Altette Car horns on A10s
Post by: KiwiGF on 16.08. 2018 13:04
I picked up a good looking and original Altette from ebay a couple of years back. All still with nicely chromed furniture. I must have lucked in as it really wasn't much money.

It turned up with connecting wires still attached but clipped an inch and a half or so away from the connectors. Left me with the horrible feeling that maybe the vendor had just half inched it from someone else's machine. It's quite out me off ever fitting it.

I have a certain paranoia for leaving my bike in the same place twice for fear someone would steal the clock - mine is on the cafe racers style plate mounted on the top fork nut. I guess after the speedo the horn is then best highest value and easiest thing to remove.

I hope yr bike is not tampered with but I hope you can see from this thread your best insurance is to pick up a suitable car horn “just in case”!

Whilst I can understand those involved in supplying horns for our bikes need to earn a living, and restoring them is not the quickest or simplest job (so I have no problem with prices like 200gbp) but just for those who want to get an adequate horn for next to nothing I hope this thread has been useful.

I bought 6 horns “randomly” for a total of something like 20gbp and I’ve got 2 half decent ones from those with no additional cost apart from a bit of paint. Some mates will no doubt get the spare ones off me as I’m easily bribed with a beer  *beer* .

I have not taken the option but on top of the purchase cost would be the cost of a chromed bezel and set of nuts is what you want to get the correct look, and there are a few sources of these (some cheaper than others). Hopefully this thread will enable readers to pick up the correct horn from a car breakers etc. if you are a rivet counter (no offence) you should be able to make sure you have the correct number of nuts on 5he back of your horn  *respect*

Cudos to Trevinoz who has provided some “missing bits” of information, and also given us the method and coil specs so we can make a 6v horn from 12v, that’s my next mini project. I’ll report back how that goes with some pics (unless Trev beats me to it).
Title: Re: Lucas Altette Car horns on A10s
Post by: Bsareg on 16.08. 2018 18:05
I was at the VMCC festival of 1000 bikes at Brands Hatch when a call went out over the Tannoy to keep our eyes out for someone carrying a Lyta tank pinched from one of the bikes there. Never heard if he was caught but there are a few good high trees at Brands if he was.
Title: Re: Lucas Altette Car horns on A10s
Post by: chaterlea25 on 16.08. 2018 18:35
Hi All,
I'm sure I heard of a similar story a while ago *????*
Hanging is too good for the bsatards *angry* *angry*

I remember some years ago seeing "security" tank centre bolts advertised
Wish I had bought some then *sad2*
At the moment I have two tanks being repainted one is an original RGS that has been de dented and rechromed
the other is a copy but quite a good one, I need to come up with something like those bolts above  *????*

Friends with vintage cars always remove radiator and other easily removable item when they put their cars on show
About two/three years ago at Stafford the stall holder next to me had a chronometric speedo stolen
later that day I spoke with another stall holder who had a rare magneto stolen
I keep all the goodies in perspex covered display boxes now, and have resorted to tying a few big items to the table using inner cable

John

Title: Re: Lucas Altette Car horns on A10s
Post by: trevinoz on 16.08. 2018 22:35
Kiwi, a couple of pictures of the new coil and as fitted.
Title: Re: Lucas Altette Car horns on A10s
Post by: a101960 on 17.08. 2018 09:11
Quote
I remember some years ago seeing "security" tank centre bolts advertised
Wish I had bought some then *sad2*
John, as far as I am aware, these bolts are still sold by George Prew.
Title: Re: Lucas Altette Car horns on A10s
Post by: chaterlea25 on 17.08. 2018 19:57
Hi A10,
Thanks, I will check with him
John
Title: Re: Lucas Altette Car horns on A10s
Post by: Slymo on 24.08. 2018 02:59
Got the rim and the new 3/8” homemade dome screws back from the platers today. Gotta say I’m chuffed with the result. Certainly prettier that the house paint yellow one that I got from my Bro.
Title: Re: Lucas Altette Car horns on A10s
Post by: kiwipom on 24.08. 2018 05:57
hi Slymo,  nice job will it fool the `bean counters` cheers
Title: Re: Lucas Altette Car horns on A10s
Post by: Slymo on 24.08. 2018 06:04
Hope so, my mate suggested punching Altette into the rim prior to plating but I thought that was asking for tuts from the anorak brigade. :)
Title: Re: Lucas Altette Car horns on A10s
Post by: Black Sheep on 24.08. 2018 06:31
Punching Altette onto the rim. Hanging offence clearly. It's not just tanks that can disappear. Came back to my Norton once and found it minus timing cover, rev counter gearbox and rev counter.  So it must have been a fellow Norton owner. Rather disappointing. At least he left me the screws. 
Title: Re: Lucas Altette Car horns on A10s
Post by: Greybeard on 24.08. 2018 09:34
Will you horn experts tell me which model I have?
Title: Re: Lucas Altette Car horns on A10s
Post by: KiwiGF on 24.08. 2018 09:50
Will you horn experts tell me which model I have?

You have a “type c” Lucas hf1234 (flat bezel, rippled tone disc, tone adjuster screw on the back). Urban myth has it that their should not be “Altette” stamped on the bezel but where the rivet counters get that info I don’t know  *smile*

Note the “type a/b/c” is not as far as I know a Lucas descriptor, just an indication of what year they were made, as the design of the Altette changed through the years. Type c is thought to be circa 1953 onwards.
Title: Re: Lucas Altette Car horns on A10s
Post by: Slymo on 24.08. 2018 12:42
No well I didn't do it although the Lucas and Altette stamps in this one look rather tasty. Other than that pleasingly like my copy. Slightly concerned that the shiney black centre looks better than my matt silver but I can change that at aother time.
Title: Re: Lucas Altette Car horns on A10s
Post by: Greybeard on 24.08. 2018 17:37
Will you horn experts tell me which model I have?

You have a “type c” Lucas hf1234 (flat bezel, rippled tone disc, tone adjuster screw on the back). Urban myth has it that their should not be “Altette” stamped on the bezel but where the rivet counters get that info I don’t know  *smile*

Note the “type a/b/c” is not as far as I know a Lucas descriptor, just an indication of what year they were made, as the design of the Altette changed through the years. Type c is thought to be circa 1953 onwards.
Thanks KiwiGF. So it may be the original for this bike. I have another horn in my box of bits. I'll dig it out and ask you about that one later.