Pedal cars help teach preschool through primary age children the skills they need to drive soap box derby cars, without the high speeds. Younger children's reaction times are not fast enough to prevent crashes and flips, which can cause serious injuries. Pedal car tracks are usually on a straight, slightly uphill run, while soap box cars are usually run on steep hills. Use a commercial frame with a front and rear wheel and pedal assembly for best results. Adjust all car body measurements to fit the commercial frame.
Cut a sheet of 1/4-inch thick plywood to 24 inches by 48 inches. Cut a hole in the sheet 18 inches from the front and rear, 20 inches across by 12 inches from front to back. Place base plate up on blocks high enough to allow you to work with the wheel assemblies, and securely enough for your child to sit safely with her feet in the hole in the base plate.
Have your child extend her feet fully, with knees locked and toes pointed up at the bottom of the base plate. Move the front wheel assembly until she can reach the pedals comfortably. Mark the position of the bar which holds the front wheel assembly in place on both sides. Mark bolt holes as well. Attach the front and rear wheel assemblies and the pedal assembly. Have your child test the pedals to see how well they turn. Adjust the front wheel assembly until she can push the pedals easily.
Adjust the size of the base plate opening so that the rear seating area is 15 inches from the rear edge of the base plate to the beginning of the opening. If there is any room to adjust the size of the hole before the point where the front wheel assembly attaches, enlarge the hole. The less wood there is in the base plate, the lighter the car will be, and the easier it will be to pedal. Do not remove so much wood that the integrity of the base plate is compromised. The hole should not be more than 20 inches from side to side.
Stand two of the 18-inch support posts at the front corners of the base plate. Drill diagonal 1/8-inch pilot holes through the support posts and into the base plate. Attach all four posts to the base plate using 1-inch long, 1/4-inch diameter wood screws.
Attach the front and rear six-sided plywood plates to the 18-inch tall supports. Attach two 6-inch pie pans to the front plate for headlight reflectors. Attach the 18-inch by 36-inch side panels to the side supports, flush with the outer front face of the car.
Attach the first pair of 24-inch by 2-inch by 2-inch vertical supports to the front plate. Attach one of the 6-inch long, 2-inch by 2-inch top supports between the tall supports, flush with the top edge.
Place the second pair of supports so that the distance from outer front edge of the first pair to outer rear edge of the second pair is exactly 36 inches. Attach using diagonal 1/8-inch pilot holes and 1-inch long, 1/4-inch diameter wood screws. Attach the 24-inch by 2-inch by 2-inch horizontal top support between the sides of the car, flush with their top edges. Attach the 3 6-inch by 2-inch by 2-inch supports as shown in the diagram.
Mitre one long edge of two of the three 6-inch wide by 36-inch long top panels to a 45 degree angle. Attach the three top panels to the top supports, with the mitred top panels on the right and left sides of the unmitered top panel. Paint car as desired, using bright acrylic colours. Apply several coats of clear acrylic sealant, allowing paint and acrylic to dry between coats.