Steering wheel adapters
Published: 2016-04-03
In this section, I describe some of the considerations of fitting an aftermarket steering wheel to airbag-era cars, including the the technical issues and workarounds.
C4 Corvette (1995)
When deciding on an aftermarket steering wheel for my '95 Corvette ZR-1, I found conflicting information about the MOMO adapter that should be used for the car. Some sources state that the 2702 should be used (with some modifications), and some claim that the 2401 is correct. Although most GM steering columns use the same splined shaft, there are apparently some differences between the telescoping and tilt columns that must be accounted for in the design of the MOMO adapter. The 2702 might be more appropriate for some Cadillac models, but the 2401 is almost a perfect fit for the late C4 Corvette.
| Measurement | 2401 | 2702 |
|---|---|---|
| Total height | 2 13/16" | 4 1/8" |
| Diameter at base | 4" | 4 9/16" |
The steering wheel on the '95 Corvette has a hole to provide clearance for the wiring on the air bag clockspring. The MOMO 2401 adapter does not have such a hole, which means that the clockspring must be removed entirely. (It only provides a connection for the air bag on this car, so no other function will be lost.) If the connector at the other end of the clockspring (underneath the dashboard) is cut off, the lead can then be pulled up through the steering column and the clockspring removed from the car.
The only other modification that I found to be necessary was removing the bulk of four small strengthening ribs in the plastic steering column shroud. These ribs are found inside the top of the shroud, and you can either grind them down with a rotary tool or cut them off with a sharp chisel. This will allow the skirt at the base of the 2401 adapter to rotate freely without rubbing on the inside of the shroud.
Finally, the switch to a MOMO wheel meant the removal of the air bag, which caused the air bag system to illuminate its fault lamp. This can be remedied by fitting a 2Ω resistor across the air bag connector in the harness. If, for some reason, you want the resistor to survive airbag-detonating current, you'll probably need a power resistor in the multi-watt range (although I wasn't able to find a spec on this.) Otherwise, it's perfectly reasonable to fit a common 1/8W or 1/4W. If you've removed the clockspring from the car as described above, there will then be a loose two-contact yellow connector under the dashboard, near the base of the column. The cleanest solution uses a mating connector, to which you wire the resistor - this allows you to leave all of the harness wiring intact. The mating connector that you'll need (which is the same as the connector at the base of the clockspring) is an ACDelco part, no. PT1159. If you want to measure the impedance through this part once you've soldered in your resistor, note that the connector produces an internal short when it's disconnected.
Jeep TJ / LJ
Aftermarket steering wheel adapter kits are readily available for the Jeep CJ and YJ, but manufacturers such as Grant, Sparco, or MOMO do not offer a kit for the TJ/LJ Wrangler. Although an adapter (such as the MOMO 2401) will fit on the TJ steering shaft, the lower part of it will occupy the same space as the clockspring assembly. Without a clockspring, the Jeep will lose the driver's airbag circuit, cruise control, horn, and the self-cancelling feature of the directionals. Only the last two of these features are particularly valuable or necessary, and they can be restored in some form even with the MOMO adapter fitted.
To do this job, it's easiest to disassemble a spare clockspring and scavenge its components:
- Self-cancelling indicators: The plastic center spool (inside of the flex cable) should be removed from the spare clockspring and modified to fit over the center boss on the bottom of the MOMO 2401. This can be done by using a rotary tool with a small end mill to remove some of the material that forms the internal structure of the spool. The spool should then be a snug fit over the center on the bottom of the adapter. I used a coating of JB Weld and a set of hardware to secure it. Be sure to align it properly first; you will want the steering wheel to be mounted at zero degrees when no steering lock is applied. If the splines on the steering shaft don't allow the adapter to fit without some deflection to the left or right, you will need to loosen the Jeep's drag link collar and turn the drag link to fix the alignment.
- Airbag warning lamp: Presumably it will be very self-evident that your aftermarket steering wheel no longer contains an airbag module, and it is possible to extinguish the warning lamp in the instrument cluster by wiring a 2 Ohm resistor across the two pins that connect to the airbag harness. To avoid cutting/modifying the car's wiring harness, you can use the small terminator board with the header pins from the spare clockspring. It's located at the outside end of the flex cable, and it breaks out the five contacts from the cable. On my 2005 LJ, the airbag pins were the two furthest toward the wide end of the board. After you wire the air bag resistor and horn switch wire (see below), the whole assembly might be somewhat delicate, so I'd recommend securing it with something like a section of large-diameter shrink tubing.
- Horn: In the OEM design, the clockspring flex cable carries the horn signal as well as the airbag and cruise control signals. After some experimentation, I decided that using a loop of wire where the flex cable once was would not be reliable; it gets snagged too easily as the steering wheel is turned. Instead, I moved the horn button to an empty slot in the center console. (OEM-looking switches are available with the "Horn" label and icon.) This avoids the need to have a rotary coupler between the steering column and steering wheel. The horn signal wire is simply shorted to ground to activate it.
Jaguar XJR (X300)
The X300 was the first generation of the Jaguar XJ to be equipped with airbag wheels in all markets and trim levels. As a result of this (and the fact that full-size Jaguars are rarely the recipients of aftermarket steering wheels), there are very few manufacturers that offer a hub adapter advertised to fit. In fact, the only adapter I could find is the Luisi CAB3506. It's actually listed as fitting the XJ8, but I confirmed that the center hole does match the steering shaft on my 1997 XJR (X300). It's a 66-spline shaft that I measured at .820 inches (~21 mm). Although the center hole was a good fit, the clockspring connector was too large to pass through the gap near the center of the adapter, so I did need to remove some material.
The Luisi adapter is drilled with two sets of holes to accept wheels using either the MOMO 70mm or Nardi 74mm pattern. Most aftermarket wheels are either a classic style (wood rim and and polished steel spokes), or very race-y. There are relatively few non-airbag wheels that look appropriate in the Jaguar X300 interior; I think the Nardi Gara 3/3 L/W is a good choice for an XJR with dark leather and walnut.