07 January 2024
First post of the new year! Work has been ongoing for the last month or so, but more so on fixing little issues with the car that have been annoyances since June of last year, and then work has focused on electronics. Being a nerdy engineer it is always interesting to me to pack plenty of modern tech into every car build. Some previous builds saw various options that did not exist when the cars were made being integrated in. Most got some sort of custom electronics that would add new functions, or enable newer devices to work in the car. This would range from modern OEM radios, to cruise control, to entire engine management systems. For instance, while it is an "old" concept now, I have a Megasquirt running my 1962 Triumph TR-3B, but it wasn't so old when it was first installed in 2007. (Yes it still works, and in fact the Triumph was driven today) So now the Crossfire is getting a similar treatment. As you are reading this thread, you know it has a M113K V8, but if you didn't catch the last few updates, you might have missed that it now has a 7-speed automatic transmission from a 2014 SL63. It took some crafting of electronics to make that work. But now it is time to add some more. As noted much earlier in the thread, the plan is to add a digital dashboard system, but before that can happen a couple of other projects must be accomplished to lead up to it. First, electronics need to be added that will gather data from many sources and digitize it. The Crossfire is still an old school car in many ways. When you turn that headlamp switch or turn signal lever, you are moving a switch that is directly manipulating the device you are wanting to use. Turning the headlamp switch directly switches the headlamps on and off. The same with the turn signal lever, and even the ignition switch. In modern cars when you do the same, a message is placed onto the vehicle's CAN bus network, and that message is received by various modules that will then trip a relay or other device to turn on and off a lamp, fan or move a motorized door somewhere. To bring the Crossfire into the next decade or two of automotive development, some of these functions need to be brought on to the CAN bus, or at least set a status of each lamp on the bus. Fortunately, the board I designed and showed earlier (below) is equipped to do that.

This board was designed and built a couple of years ago. It is mostly outdated now, but it still works. (There is already a more modern, easier to use and tailored PCB on the drawing board) By connecting to the wiring in the car for each of the lamps and switches, the status of those can be digitized and added to messages that newer devices will understand. At the same time, we can add newer devices to the car, and read their data from the CAN bus and turn those into usable functions. Enter the second item to accomplish: a modern steering wheel with buttons for the radio, dashboard and paddle shifters, just like a newer car! Several steering wheels were purchased and tested on the bench. In hand now is one from a C63 (W204), E300 (W212), E63 (W213), and another C63 (W205). The silver of the W204 wheel matches the CF the closest, but it has red stitching and it will clash with my black and grey interior (besides, my son claimed it for his SRT6 that he swapped a cedar red interior in to). So, the E63 (W213) wheel it is!

CATUION: Before proceeding with this story, you must understand that a steering wheel is a safety item, and it contains another safety item, the driver's side airbag. These are engineered and crafted for each specific vehicle, and then tested relentlessly to ensure the highest level of safety possible. Changing these is inherently unsafe for most situations. In other words, it's risky. If you read this, and decide to follow anything you see in this, do a lot of research, and then anything you do, you do it at your own risk. No pics or step-by-step instructions of this process are included as a result.

The 2003-2006 Crossfire uses a single stage airbag, and the 2007-08 Crossfire uses a more modern dual stage airbag. Pretty much everything made after 2007 features this dual stage airbag, including all of the steering wheels listed above. The subject Crossfire is a 2004 - single stage airbag. Eventually this car will to go to the later Crossfire dual-stage setup, but for now, it is a 2004 single stage system. Next, the Crossfire uses a clockspring mechanism with four wires in it. Two for the airbag, one for ground, and one for the horn. That's it. The W213 steering wheel has four wires for the airbag, and three wires for the button controls. Plainly, something would have to be changed to add more wires. In this case a W203 (C-class) clockspring was used, as it has four wires for the airbag and four wires for everything else the W203 had in the steering wheel. It is very close to the Crossfire/R170 clockspring, but it has slightly different mounting, it is thicker and one of the connectors is different. If you get one of these, make sure you get the connectors that run down the steering column to the car. The turn signal switch has a bracket to it that holds the electrical connector, and this has to be modified to allow the W203 connector to fit. Once that is on, you'll find that the splines of the new wheel are the same but the outer diameter of the shaft is too large to fit the clockspring, so the wheel itself will have to be turned on a lathe to get that to fit. Then you will see that the spline section is about 10mm longer than the Crossfire, so you will need a longer M16x1.5 bolt to hold the wheel on. You will also have a nearly 3/4" gap between the wheel and the steering column that is ugly as sin. My son @QuadPrism , a mechanical engineering student and wanting the W204 wheel in his car, designed a sleeve that was 3D printed, and is simply glued to the steering column plastic, covering this gap up nicely. So that solves the mechanical aspects of the wheel. This is what it looks like installed:



So it looks quite good in there, but it feels absolutely perfect in the hand! The thumb cutout areas of newer steering wheels really do a lot for positive feel and control. That alone is worth it. The yellow lights on the A-pillars are for blind spot protection. The system works quite well, but unfortunately will not work with the Crossfire out of the box, as the Crossfire does not put needed data onto the CAN bus to make it work. The system itself is an off the shelf device, but designed for a more modern car. It will light up one of the yellow LEDs when someone is in your blind spot, and if your turn signal is on and someone is in the blind spot, it will beep at you. Also, it will sense traffic and people walking behind you when you are backing up, again beeping at you. Very nice setup! Available here: Unfortunately, it has gone up in price pretty significantly since I purchased it. Also, it will not work with the Crossfire as-is, because the Crossfire does not put data it needs onto the CAN bus. I hope to offer some electronic devices in the future that will enable everyone to add more modern tech to their Crossfires (and other MB products) at reasonable prices and low installation complexity. If you have a newer vehicle that needs blind spot protection, this system is pretty good.

I have a whole M113K V8 Crossfire with a 7g MCT transmission mocked up on a bench to develop these devices out. Every control module is wired up, programmed, and all "think" they are in a car. This speeds up development and testing tremendously! Once the device for this function was working on the bench, it was moved out to the car for testing. Here is a video showing operation of the paddles, directly after getting it to work:

A road test happened shortly after, and it worked perfectly! Now back to the red circuit board above to enhance the functionality, and bring all the various devices that are deployed in the car into a single unit that does it all, and is tightly integrated. More on that to come in a bit. Thanks for reading!