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Replacement Horn


luckylendy

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I just ordered one on ebay at the $11.50 Buy It Now price. For $11.50, it's worth a shot. Taping a duck to the front fairing would be better than the stock horn.

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Yeah, I just got mine today, and the box says Hella, and the horn says "Made in Germany". It's dustier than heck, looks like it's been sitting in a warehouse somewhere for a couple years.

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Having repaired dents on quite a few Benz's in my day while at work, and having the factory alarm go off when you open the door without disarming the car, I can attest to the fact the horn on the Benz ML series SUV is FREAKIN LOUD.

I thought I would try out the 12 buck Benz horn as an experiment, bolted it up and holy xxxx ! It is FREAKN Loud. Cheap and quick solution..... I am going to replace the flimsy two piece stock bracket with a stiffer 1/8 inch steel bracket though.....

Just note that they made those mounting pieces thin and flexible as it helps the horn sound as loud as it can, cause it has to vibrate (attenuate). The whole science in designing a loud horn is kind of strange in a way as the slightest modifications on them can really affect their volume. Strangest thing I encountered was when I drilled a very small hole (less than an 1/8th inch) at the bottom of the plastic portions of one of my Fiamme snail type horns to make sure water does not collect in it during wet rides. Surprised when the volume of the horn was reduced by three quarters. Sealed up the tiny drain hole I drilled with bit of silicone and the volume came back to normal...... mounting some horns too rigidly can have similar negative effects
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Good point about mounting. Sometimes there really are reasons for weird things like those two-piece brackets.

That Merc / Hella horn sounds (no pun intended) like a nice deal. The prettier looking ones usually sold in dissonant sets as "Supertones" are two to three times the price per disc.

I worry about TNRabbit's allegation of "plug and play wiring" though.

If this Hella is indeed anything like the Supertones, it probably draws two to three times the current of the stock horn. It's the sort of thing that will work fine... for a little while! If you're lucky you just blow a fuse. A little less unlucky, the horn switch contacts get destroyed after several uses. All the VFRs I've seen don't bother to use a horn relay and switch the current directly from the handlebar.

Good rule is that any horn that's loud enough to impress is going to draw enough current to require a relay.

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Good rule is that any horn that's loud enough to impress is going to draw enough current to require a relay.

Not being fluent in electrical wizardry, is there a simple solution to protect the OEM components? Maybe an over the counter, standard type relay that we could add midway between the switch and the horn?

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Good point on the current draw. I may have to stick a relay in there on that horn. Wish I knew how many amps it pulled. Guess I'll do a bit of checking before I mount it.

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Since I am pretty much a dumbass when it comes to coming up with electrical wiring diagrams or circuits, does anyone have a nice schematic or parts list of something that would work as a relay for this horn. I bought the same large Hella horn and would like to eventually install it.

Thanks,

Nick

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By a standard 30amp relay, then feed the existing horn wires inside the left fairing. mount the relay there & use it as the control circuit.

Then run a fused 10amp+ cable from the battery positive terminal to one of the relay switched load connectors & a short negative cable to a good earth. Job done.

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Having repaired dents on quite a few Benz's in my day while at work, and having the factory alarm go off when you open the door without disarming the car, I can attest to the fact the horn on the Benz ML series SUV is FREAKIN LOUD.

I thought I would try out the 12 buck Benz horn as an experiment, bolted it up and holy xxxx ! It is FREAKN Loud. Cheap and quick solution..... I am going to replace the flimsy two piece stock bracket with a stiffer 1/8 inch steel bracket though.....
Just note that they made those mounting pieces thin and flexible as it helps the horn sound as loud as it can, cause it has to vibrate (attenuate). The whole science in designing a loud horn is kind of strange in a way as the slightest modifications on them can really affect their volume. Strangest thing I encountered was when I drilled a very small hole (less than an 1/8th inch) at the bottom of the plastic portions of one of my Fiamme snail type horns to make sure water does not collect in it during wet rides. Surprised when the volume of the horn was reduced by three quarters. Sealed up the tiny drain hole I drilled with bit of silicone and the volume came back to normal...... mounting some horns too rigidly can have similar negative effects

That's my problem .

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Good rule is that any horn that's loud enough to impress is going to draw enough current to require a relay.

Not being fluent in electrical wizardry, is there a simple solution to protect the OEM components? Maybe an over the counter, standard type relay that we could add midway between the switch and the horn?

Thanks Dutchy for another of his excellent drawings. Perfect illustration of how to use an aftermarket horn and standard relay to protect the OEM switchgear. Yes, those numbered markings are for a fairly standard automotive relay.

The illustration doesn't explicitly show how the electrical path works. But I'm sensing that might be getting ahead of you?

The idea is simple. Use the existing horn wiring to trigger a relay instead supply current to the horn directly. A relay is basically a switch that is operated by electricity instead of with your finger. Supply electricity to the magnetic coil of the relay and the electrical contacts of the relay close. Those contacts manage the electricity on an altogether separate, additional path of electricity from the battery to the aftermarket horn.

-Brad

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Oh yeah I forgot, relays have an amperage rating too; I'd say get a 30A and you're good as gold.

Use a decent gauge thickness wires and use heat shrink tubing on the connectors

adhesivelinedheatshrink72-450.jpg

Or connectors that have heat shrink already on them

wt10-n.jpg

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Probably a good subject for another thread about wiring but unless your bike is a sunny weather queen, it's best to use marine-grade connectors and heat-shrink Some of the stuff marked as waterproof at Autozone/Pep-Boys is good enough. The good shrink tubing has an adhesive coating inside it that helps form a waterproof seal. Buy marine grade hook-up wire, too. Uses more, thinner strands, all plated, holds up to vibration and corrosives (water) much better.

Tie down all the wiring so it doesn't shake or vibrate.

Another thing... Dutchy reminds us that relays have current ratings. Well so does wiring. A typical lightweight gauge like #18 is more than fine for the wiring that controls the relay but use at least #14 or even #12 (remember smaller number means heavier wire) for the wiring from the battery to the relay, from the relay to the horn and from the other horn connection to ground.

This isn't just a matter of over-loading the wire itself, but the fact that lighter wiring will cause electrical losses that will result in decreased sound output from the horn.

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Good point on the current draw. I may have to stick a relay in there on that horn. Wish I knew how many amps it pulled. Guess I'll do a bit of checking before I mount it.

Your wish is my command.

Stock 5th Gen VFR horn - 1.84A

Hella 335Hz horn - 4.5A

The horn circuit is on the same circuit as the stop lights and the turn signals on the 5th Gen. The stoplights pull 3.41A.

Stoplights + Stock Horn (likely usage scenario) = 5.07A

Stoplights + Hella Horn = 7.60 A

Add in the turn signals, which are a little harder to measure current because of the cycling and you have:

Stoplights + Turn signals + Stock horn = 9.55A

Stoplights + Turn signals + Hella Horn = 11.41A

All of this on a 10A fuse. These were all measured at around 13V, so running will change the values a bit.

Common wiring logic says loads should be fused 125% greater than what they draw, so I would expect not to see over 8A for the factory horn, stoplights, and turn signals, not the 9.55A I saw.

With the combo of Hella horn, the stoplights, and the turn signals, a desireable fuse rating would be ~14.2A.

So it boils down to this: Is it safe?

I'm going to say it's likely to be okay. The most likely usage scenario is horn + stoplights. In this case, the Hella horn and stoplights together pull almost 2A less than the factory horn, stoplights, and turn signals together. With the horn being a very temporary load, I think it should be fine. If you find yourself using the horn a lot while merging with your turn signals on, then I would recommend going with a relay. I rarely use my horn, and I plan on replacing my stock taillight with the Thurn LED which should reduce draw further. Anyone with better electrical knowledge feel free to contradict me and show me the error in my ways.

RD

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Good point on the current draw. I may have to stick a relay in there on that horn. Wish I knew how many amps it pulled. Guess I'll do a bit of checking before I mount it.

Your wish is my command.

Stock 5th Gen VFR horn - 1.84A

Hella 335Hz horn - 4.5A

The horn circuit is on the same circuit as the stop lights and the turn signals on the 5th Gen. The stoplights pull 3.41A.

Stoplights + Stock Horn (likely usage scenario) = 5.07A

Stoplights + Hella Horn = 7.60 A

Add in the turn signals, which are a little harder to measure current because of the cycling and you have:

Stoplights + Turn signals + Stock horn = 9.55A

Stoplights + Turn signals + Hella Horn = 11.41A

All of this on a 10A fuse. These were all measured at around 13V, so running will change the values a bit.

Common wiring logic says loads should be fused 125% greater than what they draw, so I would expect not to see over 8A for the factory horn, stoplights, and turn signals, not the 9.55A I saw.

With the combo of Hella horn, the stoplights, and the turn signals, a desireable fuse rating would be ~14.2A.

So it boils down to this: Is it safe?

I'm going to say it's likely to be okay. The most likely usage scenario is horn + stoplights. In this case, the Hella horn and stoplights together pull almost 2A less than the factory horn, stoplights, and turn signals together. With the horn being a very temporary load, I think it should be fine. If you find yourself using the horn a lot while merging with your turn signals on, then I would recommend going with a relay. I rarely use my horn, and I plan on replacing my stock taillight with the Thurn LED which should reduce draw further. Anyone with better electrical knowledge feel free to contradict me and show me the error in my ways.

RD

Your dead on and the easiest solution is to install LED's bulbs.

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Thanks for the info, that's great. I have the wire, relay, and fuse block, fuse block is already in use for other accessories, so I guess I will just run the horn off the relay through the fuse box. Looks like a 5A fuse will be good.

I got the horn mounted and it fits right in there. I figure to mount the relay right above it and run some 12 gauge wire from the fuse box to the relay and then to the horn, and back to the fuse box. Could just ground it near the horn, but as long as I'm doing it, might as well do it all. Then use the horn button to energize the relay. Should work like the business. :beer:

LED bulbs sound kind of kewl though.

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Thanks for the info, that's great. I have the wire, relay, and fuse block, fuse block is already in use for other accessories, so I guess I will just run the horn off the relay through the fuse box. Looks like a 5A fuse will be good.

I got the horn mounted and it fits right in there. I figure to mount the relay right above it and run some 12 gauge wire from the fuse box to the relay and then to the horn, and back to the fuse box. Could just ground it near the horn, but as long as I'm doing it, might as well do it all. Then use the horn button to energize the relay. Should work like the business.

LED bulbs sound kind of kewl though.

I think I'd run a 7.5A fuse. With the horn pulling 4.5A , you need a bit of overhead.
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Yeah, you're probably right, I'll have to see if I have any. I know I have 3, 5, 10, 20, and 30. Not sure about 7.5 though.

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Thanks to SCguy for the current draw recon work.

Switching to LED signal lamps helps with the overall circuit draw and gives the stock fuse the breathing room it may need, but that doesn't make up for the fact that you're pulling 2.5x the current through the horn switch and its wiring as it was designed for. The losses in the stock wiring will be slight but enough to lessen the sound output from the horn. Nothing in the wiring or the switch will melt but repeated switch actuations will over time cause pitting on the switch contacts and inevitably a failure will occur. Hopefully that failure will not be at the very worst possible time.

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MarantzManiac, are those the right pages for the LED lamps? The one you have for brakes says it's for turn signals. I'm thinking I might go this route and want to get the right one the first time.

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A sound argument can be made that all switches will fail inevitably... but don't go tooting your hella too much or a little pitting will be the least of your worries...

Sound argument. LOL. Ignore good advice at your own risk. A horn switch isn't something you want failing unexpectedly and OEM switchgear already has enough challenges with weather exposure, etc. Shifting the larger currents through the path of a relay means either the cheap and easy to find and replace relay will inevitably fail instead of your bike's expensive (and possibly difficult and/or lengthy to source) OEM switch.

Aftermarket horn kits come with relays for a good reason. I think it's amusing when backyard engineers are convinced they know better.

Yeah, do it the lazy way. It'll work. Until it doesn't. But it'll be more reliable AND louder if wired properly.

http://www.rattlebars.com/avalanche/relay_basics.html

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