How I replaced my horn with a loud trio of horns on my R1100RT

[Miguel!]

This is a long post. I wrote it primarily for other that want to swap out their OEM horn on the R1100RT for a much louder and pleasant sounding horn. I wrote it with the detail I wished I could have found when searching for information on how to do this. Also, prior to this, I'd never had the fairings off my bike and that was a bit challenging because I didn't want to break anything or lose parts. 

 

You may not want to read this post unless you are interested in changing out your OEM horn. 

 

I got my R1100RT about 1 year ago and I've wanted to replace the horn ever since. The BMW OEM horn is just too weak and doesn't have the commanding presence of a car or truck horn. I've replaced the horn on my other bike 10+ years ago and I have found it effective, especially on freeways where its already loud inside a vehicle cockpit and music might be playing. I know loud horns or even using the horn is controversial amongst some members but I am an active horn blower. I give anyone a courtesy toot if they can pull their car or bicycle or person into my path and they aren't looking at me. Some give a small wave, others a scornful look. Either way, I'm just trying to get their attention. Regardless, I replaced my horn and this post is about how I did it.  

 

It was a four step process: 1) selecting horns; 2) Taking the fairings off to mount the horns and ; 3) figuring out how to wire them up with a relay; 4) and putting it all back together. This was a much longer and time-consuming project than I expected.  I spent the better part of a week on the project because I didn't know how to do any of this to begin with or even if I'd be successful. In the end, I was successful and figured I'd write all this up for anyone else interested in replacing their meep-meep horns with one commanding attention. 

 

The first thing was determining which horn(s) to purchase. I reviewed horns online for hours but ultimately decided to buy a bunch of horns and do a listening test and measure their loudness myself, all in one afternoon. I wrote up this horn comparison and posted it on the Motorcycle Talk forum since it was applicable to all model motorcycles.

 

I ultimately selected the PIAA Super Bass Horn (actually two horn components) and a Fiamm horn so I ended up with three horns to install. I did this because each horn operates at a different pitch so, together, they have a harmonic sound structure. For the record, they operate at 330 Hz, 400 Hz and 500 Hz. And together, they are quite loud, just what I was looking for. Its easily louder than a car horn but not as loud as a semi-trailer truck or train air-horn. 

 

Next was where to mount the horns. I felt they had to live in the front of the bike. Some people mount horns on the side of the bike, attaching to some frame member but they generally are not aimed forward and are much louder on one side of the bike than the other. So I mounted them under the front fairing and aimed them down and forward. I removed the OEM horn and used the mounting stud to mount the two PIAA horns and mounted the Fiamm on another structural member. Details below.

 

Accessing the area under the front fairing requires removing a fair bit of body components. Overall, I was cautious and moved relatively slowly since I'd never done it and had no idea if I was going to pull something off and not be able to get it back on. Anyway, for people that haven't done it, here's what I did.

• Remove the seat using the key in the lock under the seat on the back of the bike. Put the seat aside, you won't need it till you reassemble the bike
• Remove the side cases if you have them on
• Remove the black triangular fairings behind the side cases. Unscrew the plastic reatainer on the triangular fairing so you can remove it. You can easily see the action inside the frame with the seat off. 
• Remove the mirrors. Chris Harris posted a YouTube video showing how to remove the mirror housing. Thanks Chris!! Pull the lights out of the mirror housings by twisting the socket counter-clockwise. Set the mirror housings someplace safe and out of the way so you don't damage them. You won't need them for a while. 
• Remove the side fairings. Each removes the same way. It doesn't matter which side you remove first. Each side has 15 aluminum screws that must be removed.The screws are all pretty obvious except the one just inside the front fairing by the radiator. You'll easily see it wen you look. 
  • DON'T LOSE THE SCREWS!! They are hard to find and are almost $3 each. Some people replace all the screws with stainless steel screws. Chris Harris in one of his videos warned against that. The stainless screws are more likely to strip the plastic threaded inserts and they also don't have the pointed tips like the OEM aluminum screw so you are more likely to cross thread and then strip the threaded inserts. I heeded his advice and treated the aluminum screws with respect and only used hand tools to make sure I didn't over torque the screws when I reinstalled them.
  • You also have to remove some dashboard screws behind the mirror mounts to get the side fairing off since they share some retaining clips on the bike's frame. Once you have the first side fairing unscrewed, remove it by pulling it up in the back to it ease it off the gas tank fairing (the edge of the fairing fits into a groove on the gas tank fairing) and then pull outwards from the top. It more difficult to describe than do it. Again put it out of the way so you don't damage it. This Youtube video by Every Joe's Garage for removing the R1100RT fairings was quite helpful. I watched it a number of times till l was confident I got it. Here's another YouTube video by IllinoisBMWriders showing the fairing removal. It is sped up and was a bit hard to follow in detail but stopping the action was helpful. BTW, I find his other video's quite helpful and informative. Thanks Joe and IllinoisBMWriders. 
  • Once you have one side fairing off, remove the bottom fairing by unscrewing the bottom screws on the other side. Support the bottom fairing with your hand while you take the screws out. You don't want to let it hang there by just one screw for fear of breaking it. Then remove the other side fairing. 
  • Remove the glove box. There are five screws including a threaded plastic stud cover on the inside. One of the glovebox screws holds a cable retaining clip. Don't forget this when you reassemble. 
  • OK. That's all I removed. I debated removing the front fairing but I thought I had enough room to work and could access everything. In the end, it might have been easier to just remove the front fairing tho to make it easier to figure out where to put the horns. Knowing where to mount them now, I'd say the from fairing removal is unnecessary. 
  • Remove the OEM horn from its stud between the forks and disconnect the two electrical spade connectors by pulling them straight off. Mine were on there pretty tight. Don't damage your hands getting them off. And don't lose the nut, you'll need it later. 
• I worked mostly from the left side of the bike because it is easier to see what's going on with the glovebox removed.
• I mounted the two PIAA horns to a 6"x6"x1 (wide)" right angle bracket that I mounted to the original horn threaded stud
  • I cut all but 1" off one side of the square bracket (creating a 6"x1"x1" bracket) and painted it black to protect it from rust and make it disappear under the fairing.
  • 
  • I then attached the two PIAA horns to the bracket. Mounting the two horns took a lot of trial and error to figure out the best mounting position so they didn't interfere with the forks or rub against any cables regardless of the fork position. 
  • Here's a picture of the horns mounted on the 6x1 bracket. I used  5/16" x 3/4" stainless bolts and stainless steel nylon lock nuts (AKA "nylocs"). Both are readily available at better hardware stores or online. I used nylocs because they won't vibrate off the bolts.
  • The angle of the horn bracket relative to the modified 6x1 bracket was determined by trial and error on the bike. You'll have to do the same but you can use mine as a guide.
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  • Note that the "trumpet-like bell" is aimed backwards but essentially points down once mounted on the bike because the horn mounting stud on the bike is raked foward. Here are a couple shots of it mounted on the bike. The 6"x1" bracket interfaces to a lip on the bike that will prevent the bracket from swiveling. Note that these shots show all the wiring installed as well. I don't have any shots without the wiring. Sorry! I'll get to the wiring in a bit. 
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  • I spent hours trying different configurations to get all three horns on there. I'll spare you the details. I finally decided I couldn't make it work and gave up.
• I mounted the Fiamm horn to a bike frame under the right fairing that holds up the front fairing. DO NOT ATTACH IT TO NOR INTERFERE WITH THE RADIATOR HOSE RUNNING ADJACENT TO THIS FRAME MEMBER! I may zip tie a piece of PVC pipe around the hose for added protection. Here's a couple front and back photos of the mounted horn.
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  • I used this 1/2" stainless steel clamp I had left over from another project. You can purchase them on Amazon and eBay. The rubber surounding the steel keeps it rotating once the bolt is tightened. 
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  • Here's a zoomed out picture of the horn on the bike. Again, the wiring is shown. I may zip tie a piece of PVC pipe around the hose for added protection. 
  • 
• Here's a closeup of the born and the right fork at its closest approach. I won't have any problems but I'll check the horn's position occasionally to make sure it hasn't moved. 
• 

 

 

I'll show the electrical wiring in another post. This one is getting too long. 

 

Miguel

[AndyS]

Or simply fit the second horn from the R1150 RT!

[Miguel!]

2 hours ago, AndyS said:

Or simply fit the second horn from the R1150 RT!

Honestly, I didn't know about them. I have since found them. They operate at 355 Hz and 510 Hz. It hard to tell from the parts catalogue how they mount on the bike so they may or may not have fit on the 1100 easily or if the existing wiring would support the power needed for two horns. The R1100RT horn wiring is pretty small, I'm guessing AWG 20 or 22. Comments?

 

Overall tho, I'm pretty happy with the loudness of the horn trio I installed. But while an interesting project, truly was a very time consuming process. 

 

Best

Miguel

[dirtrider]

56 minutes ago, Miguel! said:

Honestly, I didn't know about them. I have since found them. They operate at 355 Hz and 510 Hz. It hard to tell from the parts catalogue how they mount on the bike so they may or may not have fit on the 1100 easily or if the existing wiring would support the power needed for two horns. The R1100RT horn wiring is pretty small, I'm guessing AWG 20 or 22. Comments?

 

Overall tho, I'm pretty happy with the loudness of the horn trio I installed. But while an interesting project, truly was a very time consuming process. 

 

Best

Miguel

 

Afternoon  Miguel

 

The 1150 RT's horn power & ground wire is .75mm & that easily powers both 1150 horns from the same .75mm power & ground wires.

 

The 1100RT used a .75mm power & ground for the horn with a tap for adding a 2nd horn. (I don't think the 2nd horn tap has a built in ground wire though so that would need it's own added ground wire)

[Miguel!]

48 minutes ago, dirtrider said:

 

Afternoon  Miguel

 

The 1150 RT's horn power & ground wire is .75mm & that easily powers both 1150 horns from the same .75mm power & ground wires.

 

The 1100RT used a .75mm power & ground for the horn with a tap for adding a 2nd horn. (I don't think the 2nd horn tap has a built in ground wire though so that would need it's own added ground wire)

Thanks for that DR. That corresponds to a AWG #22 stranded wire. Looking at some tables online, #22 stranded wire is capable of carrying only 2-7 amps, depending on which table you look at. I've not been able to find the amperage used by the BMW OEM horns but I guessed 5 or 6 amps so a #22 wire would just be to small for two horns. 

 

Thanks

Miguel

[dirtrider]

19 minutes ago, Miguel! said:

Thanks for that DR. That corresponds to a AWG #22 stranded wire. Looking at some tables online, #22 stranded wire is capable of carrying only 2-7 amps, depending on which table you look at. I've not been able to find the amperage used by the BMW OEM horns but I guessed 5 or 6 amps so a #22 wire would just be to small for two horns. 

 

Thanks

Miguel

 

Afternoon  Miguel

 

The 2 horn BMW 1150 uses a .75mm wire (single wire run from the relay to the horn split)  & fuses that circuit with a 7.5 amp fuse. Seeing as BMW fuses to the circuit not the device that tells us that a 7.5 amp fuse easily handles the circuit load plus the added instant overload protection.

 

The BMW horn wire-runs are pretty short so that increases the wire load carrying ability.   

[RogerC60]

I had owned my R1150RT for about a week before ever trying the horn. First time I did I was very pleasantly surprised. It has a far better horn than either of my 4-wheel vehicles (Nissan Rogue SUV and Nissan Frontier small pickup truck). It somewhat reminds me of my (long gone) '69 Chevy Impala. So apparently 22 AWG is perfectly sufficient.

 

[AndyS]

Yes, those of us that had the twin tone 1150RT horn and have now migrated to the new Wetheads really miss that sound. 

[RK Ryder]

If one were to simply use the existing BMW wire that runs to the existing horn, why would that wiring not work without having to use use a relay? 

[dirtrider]

8 minutes ago, RK Ryder said:

If one were to simply use the existing BMW wire that runs to the existing horn, why would that wiring not work without having to use use a relay? 

 

Afternoon RK Ryder

 

It really depends on the added horn load. If the added horn(s) draw more current than the dual horn BMW system then you would need to add a power relay & separate 12v source . 

 

A number of available aftermarket horns draw a fairly high amp load so those would need an added  power relay.

 

If just using the BMW 1150 horns then those are sized to run on the stock wiring & fuse size so those shouldn't need an additional  power relay. 

[Miguel!]

On 12/24/2019 at 12:52 PM, dirtrider said:

 

Afternoon RK Ryder

 

It really depends on the added horn load. If the added horn(s) draw more current than the dual horn BMW system then you would need to add a power relay & separate 12v source . 

 

A number of available aftermarket horns draw a fairly high amp load so those would need an added  power relay.

 

If just using the BMW 1150 horns then those are sized to run on the stock wiring & fuse size so those shouldn't need an additional  power relay. 

RK Ryder,

Adding to DR's comment a little further, if you exceed the wire's amperage, hopefully the fuse blows. If not, its possible to melt the horn wire and possible damage in the same bundle. I didn't think it worthwhile to take a chance. That said, I was able to use a 15 amp fuse on the wire feeding the horns from the relay so maybe it would have been possible but I almost always over-build. 

 

I'll tell you the most work was trying to shoe-horn the horns in place, not the electrical wiring. 

 

Best

Miguel

[FarmallA]

Hello everyone

Does anyone know if the stock R1100RT single horn is the high note (of the 1150 pair) or the low note. Or is it neither?

I’d like to add the one I don’t have, the harmony would be better than the unison. 
 

I do like pretty music. 

[Miguel!]

Compared to my horn trio consisting of 330 Hz, 400 Hz and 500 Hz, the 1100RT horn has a higher not than any of them. 

 

Best

Miguel

[FarmallA]

Never mind, I just answered my own question about the single R1100RT horn. It’s is the single “pancake” horn, not one of the snail horns that are on the 1150. Oh well. Looks like I’m looking for a pair of the 1150 horns. 
 

BTW, the pancake horn seems to be about D# above middle C, (approximately 311.127 Hz).  It even wavers a little in pitch. It’s not a pretty sound at all. 😳

 

Steve

[FarmallA]

Thanks for the reply Miguel!  Yeah, the sound from the stock 1100pancake is such a mishmash of harmonics, it’s hard to tell what the note is.  Maybe its an octave above what I thought. To me it sounds bad (though maybe that’s what’s needed in a warning horn). 
 

The good thing is it’s going to be a while for enough ice to melt from my driveway to be a concern. 

 

Steve

[Miguel!]

I'm quite happy with the horn trio I put together. I think I said this earlier but I tried including the OEM horn but I couldn't fit it so gave up. I read someplace that someone had tried including it with some dual horn combination but they didn't like the combined sound so I dropped the idea. I'll get a sound recording of both the OEM and my horn trio this weekend for comparison. 

 

By contrast to snow in the driveway, I plan to get out for a 2-3 hour ride tmw. Sunny and 60 degrees, typical winter temps for my area. Sorry!! Rain on Sunday tho so no riding.

Miguel

[Miguel!]

I finally did a video of the horn. IT IS LOUD!! I rode out to a farm area so I could play it a relatively long time without attracting attention. When I give it a toot, people pay attention and look at me which is what I want. If I lay on it, it sounds like an 18-wheeler. 

 

The YouTUbe video description provides a link to a train video. My horn trio has a pitch similar to many of the trains but obviously not as loud. 

 

Best

Miguel