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Klaxon horn installation

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wkilleffer

wkilleffer

Jedi Knight
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I've decided that it would be great fun to install a klaxon horn under the hood of my MGB. It's not that I've got nothing better to do, but it sounded fun.

Has anyone else out there done this before?

It looks like I could fasten the horn to one of the radiator surround braces up front, and ground it up there as well. Then, run the +wire to the fusebox, from there run a wire to a pushbutton switch mounted on the console in one of those blanking spots, and ground the switch behind the console.

Trouble is, I'm not sure where to get the switch nor which one to buy. I'm also not sure which terminal to use on the fuse block. Is an additional line fuse needed?

Any suggestions would be appreciated.

Thank you,
 
OH! if you do it that way the horn is either going to blow all the time or blow the fuse. Activating the horn should be accomplished by grounding its coil via the cockpit switch.---Keoke
 
[ QUOTE ]

OH! if you do it that way the horn is either going to blow all the time or blow the fuse. Activating the horn should be accomplished by grounding its coil via the cockpit switch.---Keoke

[/ QUOTE ]

Are you sure? The circuit wouldn't be complete unless I pushed the button. Without conductivity, the horn won't make noise.
 
All LBC horns are activated by grounding the horn's coil unless they choose to use a relay.--Keoke- /ubbthreads/images/graemlins/yesnod.gif
/ubbthreads/images/graemlins/savewave.gif---- /ubbthreads/images/graemlins/savewave.gif
Yes, Grounding the coil generally utilises the black wire which is routed to the horn button..
 
When you say ground the horn's coil, what do you mean? Isn't that the same thing as grounding the negative wire that comes out of the horn? One of the wires coming out of the factory horns is just a ground wire that ends up grounded to the body somewhere. The factory horns don't use a relay, nor does my idea presented here.
 
What he means is that the horn has +12V all the time. When you push the horn button, you complete the circuit by grounding the horn's coil causing it to operate.

If you add a Klaxon and don't use a relay, I can almost guarantee that you'll melt something from the current draw.

I've added Hella air horns to my B, using a relay and mounted where you suggest. I'll find a photo.
 
OH!,Scott! Thank you for those kind understanding words.---Keoke- /ubbthreads/images/graemlins/laugh.gif
/ubbthreads/images/graemlins/savewave.gif
Scott do you know how much current that horn draws then we can come up with a safe circuit for him?.
 
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Yes, Grounding the coil generally utilises the black wire which is routed to the horn button..

[/ QUOTE ]

Out at the horn, isn't it purple/black?
 
[ QUOTE ]
All LBC horns are activated by grounding the horn's coil unless they choose to use a relay

[/ QUOTE ]

All cars, not just LBCs, that place the horn button on the steering wheel activate the horn by grounding. Trying to switch power with a button on a wheel that is constantly moving would be quite a challenge. Either power is applied to the horns and the horns are then grounded by the horn button, or power is applied to a relay which is operated by grounding the relay coil through the horn button.

With the relay, you can either apply power to the horns and let the relay provide them with ground, or you can ground the horns and let the relay provide power. Generally, it is prefered to let the relay provide power to horns that are grounded. This reduces the potential for a short in the horn power wires, as the power wire to the horns is only hot when you push the button. If you were to apply power to the horns and operate them by letting the relay switch ground, you would have the horn power wires hot all the time.

Either way will work, but the fewer hot wires you have running around the car, the less your chances of having a fire from a short circuit.

William, your description of your wiring scheme was OK until you got to the part about grounding the switch. With power on one side, and ground on the other - Zowee! Zap! Not good!
 
Yes Scott, for the stock Lucas horn wiring circuit the hot lead is generally purple and the return is purple with a black tracer. Add ons usually have a red and black wire .---Fwiw---Keoke

Well yes Danmas, reading your above post but it is still preferable to switch the relay ground when applying power to the horn.
 
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Well yes reading your above post but it is still preferable to switch the relay ground when applying power to the horn.

[/ QUOTE ]

That's what I was trying to say. In fact, I don't know of any other way to do it with a steering wheel horn button.
 
What is presented here in this thread is an auxiliary type horn that is not excited via the car's horn button. Consequently, there exists a greater margin for error in the choice of circuits.---Keoke
 
LOL, I had to read that three times Keoke.

You work in the Government?
 
For the switch
Use a momentary on switch that can handle the load. I used a starter button (installed in the dash) from an old car when I installed air horns in my boyfriends Volvo. An electronics store should have a momentary on switch available, just get one with a high enough amp rating. With my car, I spliced into the ground wire going to the horn button with a rocker switch. The A position on the switch would allow the stock horn to sound when I pushed the horn button and the B position of the switch would allow the air horn to sound when I pushed the horn button. If you are going to use the horn button in the steering wheel to sound the klaxon, you should install a relay to avoid a high power draw through the horn button.
 
[ QUOTE ]
LOL, I had to read that three times Keoke.

You work in the Government?

[/ QUOTE ]

/ubbthreads/images/graemlins/lol.gif Your too much Jack. haha /ubbthreads/images/graemlins/lol.gif I got a good chuckle out of that one!
 
[ QUOTE ]
For the switch
Use a momentary on switch that can handle the load. I used a starter button (installed in the dash) from an old car when I installed air horns in my boyfriends Volvo. An electronics store should have a momentary on switch available, just get one with a high enough amp rating. With my car, I spliced into the ground wire going to the horn button with a rocker switch. The A position on the switch would allow the stock horn to sound when I pushed the horn button and the B position of the switch would allow the air horn to sound when I pushed the horn button. If you are going to use the horn button in the steering wheel to sound the klaxon, you should install a relay to avoid a high power draw through the horn button.

[/ QUOTE ]

So, you spliced the switch to ground one horn or the other?

Sounds good, and I'm planning on adding a relay no matter what. Where did you get the switch? I'm a little hesitant to do anything that involves changes to the factory wiring, but will look into it.

Thank you,
-Bill
 
How much more complicated will this installation be with the addition of a relay? I've decided it's a must no matter how I do the installation. How does it fit into the circuit? It's kind of a new thing to me.

Thank you,
-Bill
 
[ QUOTE ]
LOL, I had to read that three times Keoke.

You work in the Government?

[/ QUOTE ]

-- /ubbthreads/images/graemlins/shocked.gif Wot; was sumpin wrong!!----Keoke- /ubbthreads/images/graemlins/wink.gif-
 
Give that "Kimberly" an "A" in electrics.---Keoke- /ubbthreads/images/graemlins/thumbsup.gif

---P.S. be a good idea to use the relay with the "Starter SW" too as they are not of a high current design since they are usually operating the starter solenoid.
 
I got the on-on rocker switch at an electronics store. Installed it in the undash panel cover. You couldn't see it unless you were looking for it.

In the Volvo, since the button was visible I chose the old starter button due to its size and looks. It was silver and shiney. I installed it in a similar location to the cigar lighter in a late model B.
 
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