Wolo Horn Installation
by Eric Kobrin
The stock Miata horn is very inadequate. I was sick of being nearly run down by SUV drivers. I found an open-box Bad Boy (WOLO) air horn at Harbor Freight.
I looked for Miata horn installation instructions online, but only found info about NA installation. I drive an NB and decided to put together a photo guide to installation. This method worked for me. I make no guarantees that it will work for you.
I had three goals when installing this horn: I didn't want to disassemble any more than necessary. I wanted to reuse the stock horn bracket. I also wanted the change to be easily reversible.
There's a bit of a size difference between the horns.
The horn bracket is in the lower passenger side of the engine compartment, in front of the radiator. From this view, all you can see is the top of the upper part of the bracket
This is a closer view of the bracket top. The hole just in front of the bracket frames a lot of the later shots. It also provides access for a socket wrench later on.
The horn bracket is divided in two parts. The stock horn mounts through the empty hole in the lower bracket.
Looking closely, you can see the stock horn hanging on the bracket.
Here's a clear shot of the stock horn through the hole. It's impossible to remove the horn from above.
Since removal from above was out of the question, I took a look from below. This is the view from the "mouth" of the Miata.
Looking though the hole, you can see well enough to work a wrench. The horn bracket is divided in two parts. The upper portion is removed from above. The horn is attached to the lower section. The two sections are held together with a 10mm bolt.
Here you can see the horn and the lower portion of the bracket. The wire on the left is connected to the horn button in the steering wheel. It is hard to remove with the bracket in place.
From below you can see how the bracket is attached. The stud sticking through the bracket is also the negative terminal for the horn.
The positive connector locks in place. Squeeze the release while pulling.
After disconnecting the positive lead. the horn is easily removed.
This is a close-up of the positive connector. You can clearly see the release mechanism
You can see the positive (left) and negative (right) terminals of the air horn. The stock horn has a positive terminal and connects to ground via its mounting stud. In order to use the new horn, a new ground connection will have to be created.
Removing this 10mm screw allows the bracket to be removed
This is the upper half of the bracket.
The full bracket is not well positioned for mounting the new horn. The new horn can be mounted using just the lower part of the bracket. This mounting allows the wires to reach and the horn to is well positioned, but it seems likely to shift while driving.
The solution I came up with was to make a hole in the upper bracket so that the horn could be mounted to it at the same position as it had been when using just the lower bracket.
I put down some masking tape and bolted the two brackets together temporarily. I traced the new hole onto the tape. I separated the brackets and drilled.
This is the finished hole. The modified bracket can hold either horn.
You can see that the two brackets line up perfectly.
The mounting bolt that comes with the Bad Boy is too long to use with a socket in the tight confines of the space in front of the radiator. A hacksaw can be used to improve the fit.
Here you can see the newly modified bracket attached to the horn. I left the old lower section in place so that I can switch back to the old horn without having to search for the bracket.
Some wire, a ring terminal, and an insulated disconnect turn the mounting bracket into a suitable grounding plate.
This shows what the connection will look like once it's back on the car. As you can see the new ground connects to the negative terminal of the new horn.
Remount the bracket without the horn attached. The old 10mm hex screw can be reused. I used the one that used to hold the two brackets together.
Insert the Bad Boy mounting bolt from the rear of the bracket.
Place the ring terminal over the bolt.
Next, put the lock-washer and nut (13mm) on the bolt. Leave it loose enough that the mounting slot of the air horn will still fit over the head of the mounting bolt.
Hang the horn on the head of the mounting bolt and tighten down the nut. This is easier said than done, but it is doable.
The last step is to connect the old positive connector to the positive terminal and the new ground connecter to the new ground terminal.
