I looked at Bergwerks' website, and figured out what their first gear start was doing - basically, looking at the speedometer pulses and energizing/deeneergizing the transmission solenoid depending on the speed (this is what you do when you go to "B" on the shifter). I thought it would be neat to build one similar in function to it, so I did. Slightly tricky aspects are cleaning up the speedometer pulses (the voltage is not computer compatible) and designing a switch that can handle the solenoid current, about an amp (I was conservative, and I used a relay). I considered making a "production" unit (I actually did this, using a more common and less expensive processor) and selling it but I think that there are too many liability factors for me to want to get involved with it. The Bergwerks unit is fairly priced, considering what it does.

__________________
86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm