I have a school project. I used an old toy truck 9.6 volt, made a homemade Pendulum switch, out of a clothes hanger wire (which is to shut the car down when it levels out, on top of a ramp). We can use only two 9 volt batteries, so I put two in parrell. The problem is the cars speed is to fast it needs to be cut about in half, or start out slower, because it jumps and the pendulum switch gets a bad contection, any suggestions.