The Stick Shift Auto Racing Simulator is a modification to commercially available steering wheel joystick interfaces for computers. It provides a much more realistic auto racing environment for computer games such as NFS (Need For Speed by Electronic Arts), yet requires no special modifications to the computer game. The computer games are very realistic in most respects, but they provide a poor imitation of clutch and stick-shift driving. This simulator add-on involves a simple mechanical modification to the ThrustMaster steering wheel and pedals as well as a true stickshift (the commercial unit just has a cheesy little knob that acts as a stick shift). An 8051 circuit monitors the stickshift, clutch pedal, and throttle; it then controls stick shift and throttle settings based on the current setting and velocity of the clutch and stickshift inputs.

Like many people I know, I immensely enjoy auto racing games like Need For Speed (Electronic Arts). They are an incredible way to experience performance car driving without the drawbacks: the expensive car, the danger of accidents, the expensive insurance, the expensive activities of the police department when I go too fast! However, the standard PC pedal/steering wheel gameport controller does not reproduce the manual stick shift that most exotic sports cars use. It is my understanding that no serious auto racer would consider using an automatic transmission car (although now that automatics are computer assisted and much more efficient at power transfer between shifts than humans can replicate, I hear that this attitude is changing). The computer game NFS (Need For Speed) would be the ultimate racing simulation if I could more realistically model the stick shift. Note that NFS does permit a choice of Manual (Stick Shift) or Automatic, but the stick shift works very crudely. To upshift, I push a knob forward once, and to downshift, I push it back. No clutch, no gear selection, not a very realistic setup.

To give me further incentive to build a better stick shift simulator, my son is turning 15, and will start driver training soon. Like every parent of a teen, I want him to be an expert driver as quickly as possible (like before he begins driving on the street!). Many states, including ours, are putting more and more restrictive driver training requirements on teenagers to try to cut back on irresponsible teen driving, I have good reason to try to assist my son to be a skilled driver before he even gets on the road. I believe that computer games such as NFS can actually help. Since our son will only have stick shift cars to learn on, it would be desireable if he already had a feel for the required clutch and sitckshift coordination before stripping the gears in one of our real cars. The Stick Shift Auto Racing Simulator will provide this training environment.

So, with these reasons in mind, I built in modifications to the Thrustmaster Steering Wheel (see photos). I added a third clutch pedal to the existing pedal system, and hooked it up to a potentiometer. This can be seen in the photo of the interior of the Pedal Controller on the left (note the clutch pedal spring is disconnected for the photo). The Pedal Controller cover was modified to accept the new pedal mechanism. The 87LPC767 microcontroller board is also inside the Pedal Controller and accepts connectors for the clutch, speaker, and the stick shift mechanism. I built a simple stick shift assembly with the standard H pattern, and put reed switches to detect which gear was active. The gear shift knob is connected to a sliding bolt assembly with a magnet. Two reed switches in parallel are mounted below each gear position (each at 90 degree orientation from each other because reed switches are magnetic field polarity sensitive). The microcontroller circuit board has a Philips 8051 derivative chip, the 87LPC767, which includes an ADC (Analog to Digital Converter). The ADC reads the clutch pedal potentiometer (the blue pot near the left pedal. The 87LPC767 monitors the ADC and the stickshift switches, and provides signals that used to be provided directly by the throttle and cheesy little stickshift knob on the ThrustMaster steering wheel. A small speaker driven by the 87LPC767 (via a transistor) provides a grinding gears sound. I wanted to make this setup work with any computer game that used the steering wheel, so the clutch and stickshift modification do not provide any additional signals to the computer—they are passive in that as long as the user does things correctly with the stickshift and clutch, the game will operate normally. However, if the clutch is released too quickly, the throttle is cut out by a relay (simulating the effect of a stalled engine). If a gear change is attempted when the clutch is out, the 87LPC767 generates a "grinding gears" sound on its speaker, and it also sends a command to put the car in neutral to the computer, rather than doing the desired gear shift. In the former case, releasing the clutch while the stickshift is in neutral "restarts" the engine, and stickshifts are once again permitted from neutral. In the latter case, the desired gear must be reattemped by pushing in the clutch again. If the sequence of gears is not up or down (eg from first to fourth), the grinding gears effect also occurs.

With a Stick Shift Auto Racing Simulator like this, I now really feel like I’m behind the wheel of a hot performance car, and my son is getting invaluable driving experience in a safe environment.