Assembling Your Car

Finally it is time to bring everything together

Tools and materials you'll need:

  • Hot melt glue gun and glue
  • A small paint brush (like you would use for painting small parts of a model car)
  • Your favorite graphite preparation
  • A Bic pen or other "stick" type pen with a slightly rounded end. (The end away from the writing point!)
  • A piece of newsapaper to cover your work surface
  • A tack hammer or other lightweight hammer
  • A nail set
  • An architect's scale or something else that makes a good base on which to balance the car
  • A piece of thin plastic (0.010" to 0.030" thick), about 1" square, with a slot cut halfway across it, just wide enough to clear the shaft of the axle nail

Steps in the process:

  • Slide the longest piece of weight stock into the rear weight hole and the next-longest into the middle weight hole. Slide the shortest into the front weight hole. Do not glue them in place yet!
  • Put the wheels on axles and very lightly press them into the axle holes (no more than 1/8" for now)
  • Balance the car on the architect's scale, making sure that it is square across the edge. If the balance point is between 3/4" and 1" in front of the rear axles, you're in good shape. If not, adjust the positions of your three pieces of weight stock to achieve this balance. (Worst case, you have to go back and cut some different pieces of weight stock, one longer and one shorter, that add up to the same total but allow you to shift more of the weight in front of or behind the rear axle, as required.)
  • Now, slip the wheels off the car and hot-glue the weight stock into the holes. Don't go overboard on the hot glue but make sure the weights are secure. (Using too much glue may put you over the 5-ounce limit even with all five screws out of the car!)
  • Scoop a very small amount of graphite out of the container with the brush and place it onto the body next to one of the axle holes. Using the back end of the Bic pen, burnish the graphite into the paint in a large enough circle to cover the area where the hub will contact the body. Repeat two or three times and then repeat the whole process for all four axle holes.
  • Do a last "spin-down" test on all four wheels. You want the two best wheels on the rear of the car. Take the worst of the four and save it for the "up" wheel in front, if you have drilled one axle hole high to lift that wheel off the track when the car is running.
  • Pick up a wheel/axle pair and place the plastic shim around the axle. With the shim between the hub of the wheel and the body of the car, and with the body of the car resting on a scrap of wood, gently tap the nail into the axle hole until it just snugs up against the shim. Then remove the shim and do not press the nail in any further.
  • Repeat the step above for each of the four wheels.