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Aspiring Mad Scientist
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I apologize in advance for not taking nice pictures, because in the moment I honestly had zero idea if this would work! Well it did, so here's my best shot at explaining how to retrofit your factory airbag into a racing steering wheel. This is NOT a full DIY tutorial on replacing your steering wheel, only some tips on how to get the airbag on there if you decide to upgrade.

This isn't technically a safe or street-legal modification. I tried to do this as safely as possible but it still had some sketchy moments. You do this modification at your own risk. I am not liable for damages, injuries, explosions or any other adverse consequence as a result of performing this hack.

Step 1: Choose steering wheel.

For something as critical as a steering wheel you absolutely do not make modifications to the wheel itself, so if you want to mount an airbag onto your wheel I recommend finding something with slots in the spokes that you can work with. Holes would work in theory, except that you really don't know where your bolts are going to go so it's best to leave things free and open. Examples below:

Nardi (Img Credit: Honda Tuning)


Momo (Img Credit: Some guy on Minkara with a really sexy interior)


If you're going to fabricate brackets, you could of course get one with holes.

Step 2. Get airbag out of car.

This is surprisingly simple. Behind your steering wheel rim, at the 4- and 8-o'clock positions, you'll feel two circular, rubber button-like things. Dig your fingernails under these caps and rip them out to expose the two bolts holding your airbag in. Grab a 10mm socket, undo these and be careful not to drop the bolts into your wheel as you angle them out. Ta-da, airbag can not be lifted off the wheel. Disconnect the horn wires (black on red on a single white plug) then you'll encounter the airbag plugs, which are similar to the Gen1. Easy enough, get the black clips off and then you can pull the yellow and orange free.

(Img credit: Spocket @ M3F)


So with airbag in your hand, now what? You need to decide whether you're going to fabricate brackets, or outright bolt the airbag into the wheel using some trick. If you can fabricate brackets read no further -- that is the safer, more proper way to go! But if you don't have those resources on hand, you can try the following trick.

3. Abusing factory metal

The reason why I suggested a steering wheel with slots is because the trick involves making new mounting points out of the factory horn bracket. I'll do my best to paint a clear picture, please have a look below:



Right in the middle you'll notice I've put a screw through the horn bracket -- and you'll notice that the screw points straight through the slot in the Momo wheel. You need to drill a hole for this so please don't drill the bracket with it still attached to the airbag -- remove the bracket (3x 10mm nuts) and lift the bracket off the airbag. Both left and right sides of the horn bracket have the same looking "ear" you will need to pierce (imagery intended). I drilled 7/32" holes to use an M5 (roughly #10 size, just metric) screw for strength.

Planning ahead: With this trick we can secure the left and right side of the airbag, but what about the bottom? You can drill an extra hole to do the same trick, but that screw will be hard to reach! OR you take make one concession to MacGyver and drill a pair of holes to run a cable tie through. You can cinch the cable tie real tight around the bottom spoke after you're done with the left and right.

4. Clamping down

You've seen the front of my right spoke, now see the back:



It should be apparent now what you're going to do to secure the airbag: Clamp the spoke in between two fat washers and pray that you apply enough holding torque to keep it in place even in a bad crash (if you do this right using big enough hardware, it will be sufficient).

What stumped me for a bit is the angle between the bracket and the steering wheel spoke: the horn bracket is pretty flat, but most steering wheels have a little concave dish to them and the Momo Mod 08 is pretty extreme in this regard. To get around this, we're going to design a little self-aligning clamp such that even if things aren't perfectly flat or lined up, we can still get a good solid clamp on the spoke. Source parts as follows, ignore the horn bracket (you're already looking at it).



With this assembly, the spoke of the steering wheel is clamped between the fender washers. The rubber washers will fit inside the slot of your steering wheel spoke, so either buy them in a size that you can get in there, or be prepared to trim the washers such that they go on. My personal parts list that I found useful:

M5x20mm screw (1 pair)
M5 tension locknut (1 pair)
1/4" ID fender washers (4pcs)
3/16" neoprene washers (6pcs)
#12 sealing washer (1 pair)

The sealing washers are key, they're the best thing I could find at Home Depot that allow for a lot of misalignment while pressing down consistently hard on the fender washers. And if I haven't made myself clear yet, the fender washers are doing all of the work to hold your airbag secure, so you better make sure that you can put a lot of clamping force on them!

Before you tighten both sides, make sure your airbag is level, as my hack makes no guarantees on the alignment of the airbag vs. your wheel. As you tighten the nuts, you'll start to see the sealing washers squish. Don't destroy the poor things, but don't stop tightening until they're noticeably squished. You should find then that there's no way in hell you can move the airbag with anything less than a hammer. Once those are tight, don't forget to wrap the cable tie around the bottom spoke, cinch that tight and you are golden!

5. Getting the horn back

The factory airbag is the (+) contact and the horn bracket is the (-) contact, hence when you push the two together you complete the circuit and trigger the horn. Maybe it's just me, but I had a terrible time with my Works Bell hub where basically anything would cause a short circuit and trigger the horn. Uh, Rude~

So anyways, my fix for now is just to route the sucker outside and grab a connection elsewhere. There isn't really a safe way to do this, I soldered to the airbag.



So yeah, looks like this when done.

 

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I'm really not sure what to think about this... On one hand, it's preserving a key safety feature, but it's also a very 'interesting' mod.
 
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