I am in the process of installing an original horn on my ‘46 Truck. I will be using a universal horn button that clamps onto the steering column. Just a simple press to blow button.
Do I need a relay or can I wire it straight?
Care taker of a 1946 1/2 ton. Pretty much period correct original. Danny T, from B’ham, Al
A relay will make the contacts on the horn button last a lot longer, especially if you're running a 6V horn on 12 volts. Of course, that depends on your personality- - - -I've used my horn maybe three times in the past 6 months. Saw a bumper sticker a while back- - - - "Horn's broke- - - -watch for finger!" LOL! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Thank you!! It’s an original system, but upgraded to 12volt with alternator.
Well then not original. Most members say it's OK to run a 6V horn on 12V. Not many fuses if any in 46. The horn is drawing the same amps as before so if you installed a new "12V" harness, the wire size and fuse needs to be investigated....as well as the button as said.
The horn is drawing the same amps as before so if you installed a new "12V" harness
Actually, the horn will have the same resistance (or more properly impedance) as before, but because the voltage is doubled the current (amps) will also double. AND IT WILL BE REALLY LOUD, at least for a while.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
The same ceramic resistor that's used for a 12V ignition coil can be wired in series with a 6V horn running on 12V- - - -problem solved. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
The definative way to answer your question is to use an ammeter to measure* how much current (units: Amps) your horn draws. With that information you can check your switch and the wire gauge you are running to see if they are rated for that much current.
Be aware that you will need to use the high current postion if you are using a standard multmeter to measure it.
Jerry's idea of repurposing a ballast resistor to drop it down is interesting. I have a 6V horn that I just rebuilt and it is *loud*. I might give that a try and see how it affects the volume.
*You could theoretically calculate the current based on the resistance of the switch/windings, but the ones that I have messed with have low enough resistance that the measurement error in consumer grade tools would be significant.
converting to 12v and new wire harness. what relays are recommended (and source) for the "loud" original working horn and also the halogen headlights?
Larry Old man᠁Old truck᠁neither one goes very fast. All you need in life is TIME, PATIENCE and MONEY. If you are missing one component, you'll need an abundance of the others two.
60 amp Bosch-style relays. They're all over Ebay at dirt cheap prices. That heavy a capacity isn't necessary, but the wires on the plug-in connector included with each one are much heavier gauge than the "30 amp" version. The relay won't care if it's not working at max capacity.
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
The same ceramic resistor that's used for a 12V ignition coil can be wired in series with a 6V horn running on 12V- - - -problem solved. Jerry
I tried the ballast resister on my dual 6 volt horns, and they would not work. I hooked them up to a full 12 volts and so far this last summer, I’ve only used mine to show people how nice (and loud) they sound!
Phil Moderator, The Engine Shop, Interiors and Project Journals
1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum
"Dual" horns- - - - -you'd need one resistor for each horn. Trying to flow enough current to run both horns through one resistor doubles the voltage drop. Ohm's LAW is not a "suggestion". Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
