Stebel Nautilus horn install

6mileZ

Like many here, I was disappointed with the wimpy horns on the 370 and longed for a way to wake up the oafs drifting into my lane. I liked the look of the Stebel Nautilus and decided to do the install. The bumper removal was a bit intimidating, but it went fine (remove bottom bolts, side bolts, top plastic doohickeys; install in reverse). The videos online helped, and I was pleased to learn that I could do it without jacking the car.

I apologize for not having pix, but I just wanted to pass along a few hints that really don't need a visual.

The horn comes with the required 30 amp relay. I also purchased the wiring kit, which was good for the required 30 amp inline fuse and better instructions than those that come with the horn. But the kit is likely sized for motorcycles because the length of wire is way too short. Plus, the enclosed female blade connectors did not work with the 14 gauge wire you need to connect from battery to relay to horn.

I bought new female blade connectors that worked with the 14 gauge wire, plus a 25 ft length of 18-2 wire to run from the horn back to the relay (the old horn used two wires, so you connect to these and run to the relay). I bought 25 ft of 14 gauge wire, too.

I installed the inline fuse and the relay inside the battery compartment. The fuse line connects to the + terminal and to the #87 blade on the relay. I ran 14 gauge wire from #30 blade on the relay to the + terminal on the horn. The 18-2 wire is used to run from the other two blades on the relay to the two wires that are removed from the old horn. I chose to keep the horn in the center and replace the horn that is forward of the left front wheelwell. The new horn fits easily into the hole of the old one.

One key is to make a good ground of the horn to the chassis. My first choice was close to the horn, but too weak, so the horn just sputtered. So I ran a new 14 ga line from the neg terminal of the horn to an obvious chassis ground on the wheelwell itself. Problem solved.

The result it impressive, much louder than the old horns but not like a train or semi. Hope this helps if you want to install a new horn.
- Jeff

Chuck33079

How do these compare to Hella Supertones? Are they even louder? I may have to throw in a set next time my bumper is off.

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2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

6mileZ

I have no direct comparison data other than the listed outputs. The Stebel is listed as 139 dB and the Hellas are listed as 118 dB.

Chuck33079

Oh wow. That's a big difference.

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2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

JARblue

Thanks for the info. I really want a train horn but not willing to spend the money or install an air compressor. These might be a good compromise

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JARblue

I purchased a horn a while back and finally getting around to install. I bought the Nautilus Compact Truck Mini Air Horn (11690058). It emits at only 110db but it’s single low tone at 300 Hz instead of the the standard 400-500 Hz horns.

If anyone knows, I am having some questions about the install. There are two OEM horns, so I’m wondering do I need to connect wiring from both old horns to the relay for the new horn? Or can I just abandon the wiring for one of the old horns and just use the wiring from the other one for the new horn? Or maybe I need to do something else?

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6mileZ

I just replaced one horn and left the wiring for the other one in place.