Momo Competition Steering Wheel Install

Here is the stock steering wheel on the car. It's the basic airbag wheel from the late 80's.
 

WARNING

I do not recommend replacement of an airbag unless you have a specific reason.
I take no responsibility if you follow these instructions and have any problems

For racing purposes, I decided to replace the stock, airbag equipped steering wheel with a lighter, non airbag wheel. After doing some research I decided on the Momo Competition wheel.

Since I wasn't sure how to install the new wheel, I put a post on Rennlist (rennlist.org) looking for instructions. Within a few hours I was looking at Tom Pultz' site ( http://www.944s2.com/ ) and I had a general feeling of the work required.

As per Tom's instructions, removing the old wheel was very easy. I disconnected the battery for 30 minutes so there was no chance of accidentally deploying the air bad. Then I removed the two Torx T-30 bolts in the rear of the wheel. That allowed the air bag to come out. The air bag is connected with a red plug, pull the plug and the air bag is out.

The torx screws are behind the red circles (from the back of the wheel).

The steering wheel is held with a single 24 mm nut. I removed it, but the wheel would not budge. I pulled and pulled and it would not come off. A friend suggested twisting it up and down, and after two or three twists it popped right off.


You can see the 24 mm nut that holds the wheel on. The red plug attaches to the airbag. The other wire is for the horn switch.

So far so good, but now it gets tricky. The replacement wheel mounts onto the steering shaft with a 'hub adapter' and the new wheel bolts to the hub adapter. The hub adapter is not really designed to work with an air bag wheel. So I had to figure out what to do (Tom's instructions helped some, but his steering wheel was different than mine.

First, you must remove more parts. The horn operates by closing a circuit. The stock wheel has a metal 'button' that rides on a brass ring. The ring must be removed. There are four phillips screws that attach a cover over the ring, or in Porsche speak, rotary switch. I removed the cover, then the two screws that hold the rotary switch. There were three wires from the dash to the switch, one was for the horn (brown) the other two are for the airbag. I removed the plugs and the ring was out.

Now I should have been all set to install the hub adapter, then the wheel. Of course, this being a Porsche and all, nothing is ever that easy. First I have to come up with a way of connecting the horn. Believe it or not,  I have used the horn on the track and it is very useful in the paddock. Since I do not like to just cut and slash electrical connectors, I found a spade connector that fit the horn plug. I crimped the connector on, plugged it in, and used some electrical tape to make sure it stays in place.
 


This is the rotary switch. One connector for the airbag, the other for the horn.

This shot shows the cable I made with the spade connector for the horn.
I put some electric tape on the connector to make sure it stays in place.

With the rotary switch removed, I could put the decorative cover back on the steering column. When I went to put the hub adapter on, I found that it hit the cover and caused some binding when the wheel was turned. No good. I emailed Doug Donsbach some questions (since he has done the same installation), and he solved the problem by removing some material from the hub adapter. So, at 10:30PM I used a 4" grinder to remove about 1/8" from the end of the hub adapter. I used a dremel to clean it up, then test fit it on the steering shaft. It fits fine.

Time to test the horn. I placed the hub adapter on the shaft, held the wheel to the hub, connected the horn wire, held everything in place, turned the key on, and pressed the horn button. Nothing, no beeps at all. Hmmm, I guess the paint on back of the wheel did not allow a ground to the steering shaft. I could sand the paint off and hope that the bolts made the ground. I didn't like that idea. So, time to create a ground on the hub adapter.The Momo people must be used to that because the horn button has another connector for the ground and they give you the wire pre made with a spade on one end and a lug on the other. I drilled a small hole in the hub adapter and bolted the ground to it. I test fit everything again, turned the key on, pressed the horn button, and beep beep. Not really the sound you want to hear at 11:00PM, but I was happy.

The rest was easy, bolt it together, torque the hub adapter to the steering shaft, line up the horn button, wheel and bolt it on. The car will run like that, but the main warning light, airbag light, and seat belt light will be lit in the dashboard. That is not something I want to have lit when I am driving. According to Tom, there are two ways you can fix that. Find the connector at the airbag module and either jump two pins or cut two wires.


 
 

This section taken directly from Tom Pultz' site:

The SRS controller is the bright orange module bolted to the underside of the dash in front of the glove box.  It connects to the car harness through a round, 7-pin connector.  The wire colors and functions are as follows:

1- brown, ground
2- red/black, central electric KL50
3- black/white, central electric N48
4- black /red, supply for DME relay
5- white, buzzer relay, seat belt
6- unused
7- yellow/black, airbag warning lamp

End section taken directly from Tom Pultz' site:

 In this shot I have disconnected the connector. I planned on jumping two pins (3 + 4, DME power) but I didn't have a suitable jumper. I tested it with a wire and the car ran, but I was not comfortable doing that. So, even though I dislike it, I cut two wires (5 + 7). It has finally dawned on me that my car is race car and will never go back to pure street car. So, I cut the wire, taped them back and put it all back together.


All done!