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horn advice

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jvandyke

jvandyke

Luke Skywalker
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The other day my horn went off an hour or so after I parked it I was told it blew for a few minutes then died down to nothing.
After I push the horn button and hear the relay click. Took horn out (Delco Remy out of something sometime) apply 12 volts and it just sparks. So, since it seems like this horn is riveted together or something I didn't get far with my usual MO of tear it down and see what's what, I need to throw one in. I guess I'll just get some generic one at a parts store? Very weird why it would go off like that on it's own, shorted internally I guess.
 
Is this on the car that you installed the custom steering wheel and horn pushbutton on?

The horn itself shouldn't have gone off unless there was either a short with the horn pushbutton or in the relay. Take a look at that spring loaded wiper pencil behind the horn pushbutton and make sure none of the wires associated with it are touching ground.

I have some used horns of unknown origin on our project Spitfire. There are usually nice aftermarket horns (Fiamm?) for sale in places like Advance Auto and I'll likely install them later in the restoration project. They are much less expensive than buying Lucas parts, even used Lucas.

If you want to open a riveted horn, I typically drill out the rivets one at a time and as I go I replace the rivets with machine screws and nuts. I seem to remember that 8-32 screws work well on Lucas horns. Inside the horn are a set of contacts (usually right under the large adjusting screw and nut... which are not on the center of the horn). The points corrode and once carefully cleaned the horn usually works again.
 
Yes it is the "custom job". I thought maybe the brush had shorted to ground, causing a full on situation but it stopped on it's own, maybe it burned out the contacts? It's installed via relay and fuse so maybe that saved anything sensitive. I'll cut off the rivets....I guess.
 
The horn if it is an orginal can be rebuilt.
 
It ain't, Delco Remy is a GM thing I'd guess, no? Just not too sure I want to spend an hour trying to resurrect an old crappy horn but well, I will because my time is free, my money cost me.
 
just remember, that the horn switch is a ground. It does not feed juice to the horns and then to ground. Juice is at the horns and goes to the push to make a ground.

m
 
Yep, although I put a relay in so the relay does feed juice to the horn, it is grounded through it's mount. I managed to grind off the "rivets" and get the top off, I think it's garbage, black stinky oozy stuff in there, a set of points, looks burnt to me like the whole thing fried, little windings in there and all that, but it doesn't matter. I'm getting a generic one from NAPA tomorrow, for $15 I'm done trying to salvage this. Glad for the relay and the fuse. Neither was there a few weeks ago. May have been a bigger problem.
Here is a picture for, well, whatever. The dark splotches are the gooey stuff.
hornguts.JPG
 
Horns aren't made to stay on a long time; probably burned the sucker up. You can get a perfectly good replacement horn at the auto store, so I'd just do that. Cheap & effective.

Also, you should make sure that the relay isn't sticking or something shorted in the horn button, as Doug mentions, or it probably will happen again.
 
Will check system over thoroughly. Still don't know what could make it suddenly go off after it sat for a while. It was hot day and I had been stuck in traffic, engine temp was alright yet everything else was feeling the heat, gearbox was stiff and sticking in gears. Maybe after it shut down the heat sink effect from the radiator caused a short in the horn itself and that was all she wrote. Maybe I should have left my electric fan run for a bit.
 
I'm not suggesting that the following applies to your situation but it is something that happened in my past.

My wife owned an '81 VW Rabbit. The center of the steering wheel was covered with a large molded plastic/rubber piece that covered the spokes and provided a contact surface to push on to activate the horn. Several times when the car was parked in a cold place, the plastic "shrank" (shrunk?) causing the horn to go off. After the third or fourth time we figured out what was going on and I modified the cover to be a bit looser and I placed some rubber foam gasket tape in a few spots to push the plastic cover away from the horn contacts. With those mods, the problem never returned.

Based on that, I'd take a look at the wiper and the slip ring for your setup and see if there is any way parts slipping or changing shape with temperature might cause the problem you're experiencing. Of course... it could be that nice looking horn button itself.
 
dklawson said:
Of course... it could be that nice looking horn button itself.
Click to expand...
Not so nice looking anymore. When this happened my 14 year old son called me on my cell, reception was so bad I had to text him instructions, "pry the black plastic piece off the steering wheel" I told him, he tried (with screw drivers) to pry the actual push out of it's plastic housing, so now it's all marred up and looking crappy....oh well. I'd take an original nice '63 in trade.........
 
I could duplicate Doug's story. I once had a '72 pinto, with the same kind of horn covering. Late one very cold winter evening in Socorro, NM (where I lived in the mid 70s), I heard a horn blowing outside. Got up, went to the door, and it had stopped. Nobody there.

After a couple more cycles of this, I realized it was MY car, sitting in the driveway, blowing its horn all by itself. I pretty quickly figured out what was going on, but there wasn't much I could do to stop it--how can you service a single-piece, molded horn, with the contacts buried down deep in the plastic? So, I just took off the horn button assembly, if I can call it that. Put it on next morning. Just the kind of thing a Pinto owner has to live with.
 
Ooooh... so sorry about that horn button. In my mind I can see the before, and after pictures. That is a real shame.
 
A much better way to stop the horn sounding is to disconnect at the horns. Just disconnect either one or two connectors, depending on how many horns. Off it is. Common way to take care of alarms that are going off.
Scott in CA
 
The horn in this case is buried behind the grill, no easy access, especially not for a 14 year receiving instructions via broken up text messages. I got a similar horn from NAPA 132dB or so. Heading out to bolt it up and see what happens.
All done, horn did not sound as I hooked it up. Can't really test as it is 1:30 am and horn testing is frowned upon at that hour, why I don't know, doesn't everyone work on their LBCs in the wee hours of the morning?
I also managed to get my electric fan properly installed (since the grill was out) and rerouted my bonnet release cable, it was always getting snagged on the bonnet catch which made it hard to get it open. Good work session. Here's to hoping the horn actually blows!
 
Had to replace the fuse before it fired up (it was blown due to overload from the shorted horn, I guess) Works again.
I did check the old horn, 12v direct and it only sparked something fierce so it was bad, whether it went bad as a source of the problem or a result of something else I don't know. All is functioning fine as far as I can tell.
 
The horn itself should not have been the problem since it was the load in the circuit. Something had to be closed to supply it power. Before you say you're done with this, do take a look at the horn relay and horn button contact arrangement.
 
Yep, looked it over, can't see anything amiss. Is it possible for a relay to get too hot and short (causing the horn to blow itself up) then cool off and work fine again? Could have been anything in the circuit I guess. I'll just have to watch things. Now wishing the horn was on a switched circuit.
 
I can't imagine anything the relay could do that would blow the horn--except to get stuck on, and then heat would fry the horn. Horns use quite a bit of current--I think the stock Sprite horn, if I remember correctly, pulls about six amps. At ~13V, that's almost 80 watts, easily enough to fry the thing if it stays on too long. So, check the horn button and maybe just replace the relay, to be safe--they're cheap.
 
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