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Home > Miata Tech > First Generation (NA) Tech > NA Steering Wheel Replacement Steering Wheel ReplacementSubmitted by "Voodoo" Bob Krueger Installing A Non-Airbag Aftermarket Steering Wheel In The MiataThe following is an edited compilation of various bits of information that I saved over the past few years from online sources such as CompuServe's Miataville and the Internet Miata mail list. I have personally, and successfully, participated in a number of these modifications that were done according to these instructions without incident. I know this method will work if done as described...at least on my and other Miatas of vintage 1990-1993 [on later cars, you may need to insert a 3 ohm (1/4 watt) resistor between the two airbag wires to fool the computer into thinking an airbag is present so that it will turn off the dash indicator light]. Anything you decide to do to your car is, however, your decision and your responsibility, not mine...which is only as it should be. I just wanted to make that clear up front. You start with a hub adapter for the Mazda 323 from any Momo or Nardi (or whichever wheel you want) supplier. The Momo part number of their adapter is 5702. The Momo hub adapter has a contact slider ring on its back side that is meant to mate with a horn circuit contact inside the clock spring assembly on a 323. This ring is encased in plastic and merely pressed onto the back of the hub with a friction fit. The ring is NOT used in the Miata installation. Just take a small screwdriver and insert it under the edge of the plastic piece. That piece, with the horn contact ring and horn wire, will easily separate from the rest of the hub adapter.
CAUTION: When carrying a live airbag module, make sure the trim cover is pointed away from you to prevent possible injury in the case of an accidental deployment. When placing a live airbag module on any surface, always face the trim cover upward to minimize the movement of the module should it accidentally deploy.
There are three wires coming from the clockspring assembly at the bottom center of the steering hub. Two of these wires go to the blue airbag module connector (the same two you will eventually crimp together) and the other wire is the +12v to the orange horn connector, to which you will add a spade connector and connect to one of the male spade lugs on the back of the MOMO horn button (this wire was green and red striped on my car). It is necessary to cut off the molded plastic connector (that originally went to the airbag module) and slide off the rubber accordion boot before you can do this. Cutting off this connector is the proverbial "point of no return". Well, you can return from here, but things will no longer be cosmetically exactly as they were if you do. Hold your breath, snip the wires at the steering wheel end, and slide the accordion boot off. You want to leave as much wire length intact as possible. The more you have to work with later, the better. Do, however, leave enough wire on the molded connector you removed (airbag end) so that the airbag can be re-installed later if desired. None of us plan to ever sell these cars, but you never know. HELPFUL NOTE: Get yourself a Dremel tool before starting the next operation. Without a borrowed Dremel tool, I would NEVER have gotten the connector body cut down to size and the extra metal hogged out of the back of the hub adapter. The next day, I went down to Home Depot and bought a Dremel tool of my own for the next time I do this job. The three wires come out of a rectangular black plastic connector riveted onto the turn signal canceling ring. They are secured with a strain relief tie-wrap. Both the tie-wrap and the plastic protrusion it's tied to need to be cut off. The remaining plastic connector is riveted onto the face of the canceling ring. In order to minimize the amount of metal material that needs to be removed from the back of the adapter hub, it is necessary to shave, file, sand, or cut as much black plastic material from around this 3-wire connector assembly as possible. The idea is to reduce the cross-sectional area of the plastic so as little as possible (width, length, and height) will protrude into the back of the MOMO adapter hub. Lay a towel down in the seat to catch all the little black plastic filings. Lay several towels while you're at it; plastic filings will be flying EVERYWHERE once you start this step. Also roll some masking tape into long, thin, sticky-side-out tubes and lay them along the lower edge of the turn signal canceling ring to prevent small pieces of shaved plastic from getting down into the steering hub area. The plastic connector around the wires is actually a two-piece affair. Use the Dremel tool to cut carefully around the base of the outer piece and remove it. You can then use diagonal cutters to carefully trim away the excess material at the outer edges of the inner piece. BE CAREFUL NOT TO NICK OR SEVER THE WIRES! Obviously, not all the plastic can be cut away, hence the need to "hog out" some clearance area on the back of the metal adapter hub. On the back of the adapter hub are two small holes 180 degrees from each other flanking the center splined hole. These engage the two small nylon protrusions on the clock spring assembly. Note that the hub adapter has TOP marked on it. Try to position the hub correctly and align the two small holes with the nylon protrusions. You will see that it will be necessary to use the Dremel tool or some other metal router to carve out a rectangular relief cut in the back of the hub to provide clearance for the remaining portion of the clockspring connector (with the now-unused airbag wires and the horn wire) because not all of the protruding connector can be cut away without endangering the wires. This relief cut needs to be centered immediately below the lower of the two small holes used for the turn signal cancelling protrusions, approximately halfway between the hole and the outside edge of the hub adapter. Finding the correct location to grind away is one of those jobs where two heads are better than one. I strongly recommend that you recruit a friend to share this job with you...to shine a flashlight on the work area if nothing else. Or one of you can hold the adapter more or less in place while the other looks at the backside of the adapter and locates the place where you must start grinding. The hub material is very soft pot metal and grinds relatively easily. Once you locate the proper starting place, you will need to drill a 3/8-inch pass-thru hole in what will eventually be the top center of your new cutout. This will be used to pass the 3 wires through the base of the hub adapter. If you have access to one, It's best to use mount the hub adapter securely in a drill press to accurately drill this hole. The position of the hole will come very close to one the hub "spokes". Be careful when the drill bit is about to penetrate the front side of the hub adapter; do not allow the drill bit to deform or penetrate the hub spoke. Once the pass-thru hole has been drilled, proceed to use a high-speed cutter (a number 117 works really well) in the Dremel tool to hog out the recessed area into which the remaining plastic protrusion will fit. This whole process will likely take several iterations of removing material and then test-fitting the hub adapter. It is definitely a trial and error procedure to determine exactly what size recess will be required.
NOTE: 1.8-liter cars may require the addition of a 3 ohm resistor between the two airbag wires to simulate the load that an airbag provides to the circuit.
From here it is mostly a matter of following the (probably pictorial) instructions that came with your steering wheel to make the stack of parts, connect the horn and ground wires to the button, and mount the steering wheel using the six hex-head bolts that came with it. NOTE: Some Momo horn buttons utilize an integrated ground wire ring that protrudes from the side of the button and articulates with the metal horn button mounting plate. These buttons will not require the use of a separate ground wire from the mounting plate to a spade lug on the button. If the back of your horn button has only one lug, you have this type. A SUGGESTION: Momo makes a 1/2-inch steering wheel spacer that sells for about $16. This piece is finished in a crinkle black that matches the adapter hub and includes six longer allen-head bolts for attaching it and the steering wheel to the hub. Using this spacer will allow for more room between your fingers and the control stalks, more closely matching the position of the Mazda wheel. I recommend that you contact your Momo dealer and obtain one of these spacers before you start the wheels swap. Believe me, unless your hands are very thin, you'll be glad you did. Stacking the accordion boot, horn grounding ring, horn button, spacer, and steering wheel properly so that they can be bolted together is another one of those tasks that will make you glad you invited a friend to help you. This part of the job is MUCH easier with one person to hold everything together while the other person gets the bolts started.
Once the wheel is on and tight, re-connect the blue and orange clockspring connectors under the dash, replace the access panel, re-connect the negative lead to the battery, and you're done. Turn on the ignition switch and verify that the air bag light goes out. Honk the horn. If you're as lucky as I was, everything will work as it's supposed to. Now isn't that better looking than the OEM wheel? Now you get to reset all your radio stations and the clock...a small price to pay for all that beauty. DisclaimerPlease note that these tips and pointers are not reviewed or approved by Mazda Motor Corporation or any other corporation or entity other than the originator. The San Diego Miata Club does not accept any liability for damage or injury as a result of utilizing these tips and pointers. Please use common sense and always remember safety first. |
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