How to Build a Pinewood Derby Car

Pinewood Derby
Lynn Seeden / Getty Images

The Pinewood Derby is one of the most anticipated Cub Scout events. Boys and their adult partners are hard at work designing and building their Pinewood Derby cars. If you're new to Cub Scouts, you may not know how to build the car. These instructions will walk you through the process.

Review Derby Rules

Before you begin designing your Pinewood Derby car, review the race rules. Your Cub Scout pack should pass them out, but if it doesn't, ask your den leader for them.

It's important to know the rules because some of them may impact your design. Some requirements in the rules are:

  • Length of the car
  • Width of the car
  • Weight of the car
  • Bottom clearance of the car

Typically, cars are inspected prior to the start of the Derby and may be disqualified if the car doesn't meet the requirements.  No one wants to see the face of a Cub Scout whose car has been disqualified.

Gather and Inspect the Car Parts

Most Cub Scout packs use the official Boy Scouts of America (BSA) Pinewood Derby kit. You'll want to inspect each part to ensure that there are no issues that will impact how fast your car is.  

The Block

  • Look at the wood block to see if there are any chips, cracks or scratches.  If there are, replace the block.
  • Place the block on a table and push down on one side.  If the block rocks, it is warped, and your car won't run properly, so replace the block.
  • Check the location of the axle grooves to ensure that they are perpendicular to the side of the block.  If they don't line up, replace the block.

    The Axles (nails)

    • Inspect the axles for defects, scratches or broken pieces.  If there are any issues, replace them.
    • Ensure that the axles are straight by placing them in the head of a drill and turning it on.  If they don't spin straight, you should replace them.
    • Look for marks along the shaft of the axles and for rough edges beneath the head.  They should be removed, and the axle sanded.  Use high grit sandpaper or a jeweler's file to polish them.

      The Wheels

      • Look for any defects in the wheels. Place them on the axles to test that they spin properly.  Replace the wheels if they wobble or don't spin continuously.

      Design and Build your Car

      Most boys enjoy this part of the process more than any. They get to use their creativity to design a cool car.  One of the most fun parts of the Pinewood Derby is seeing what kinds of cars the boys create.

      Draw it Out

      • Using graph paper for scale, draw out the plans for the car before you start actually building it.
      • Use the squares on the paper to measure your car so that the length, width, and height are within the acceptable limits.
      • Note where the axles and wheels will go. If the wheels aren't marked, they may cover up part of your design on the finished car.

      Cut it Out (Only with adult supervision)

      • Cut out the design from the graph paper.  You can tape it to your block for a good template.
      • Cub Scouts aren't allowed to use power tools, so a parent will need to cut out the design for them.  An exception to this is for mature boys who can use a hand saw such as a coping saw.  
      • After the initial design has been cut, add details using a wood rasp.

      Sand It

      Your car will need to be sanded until it is smooth.  Use rough, medium or fine grit sandpaper to accomplish this.

       Rub your car with a clean cloth to remove any dust after you've sanded.

      Add Weights

      The weight of the car is what determines its speed.  When you are cutting out your design, you are also removing weight.  Cars should be as close to the weight limit as possible, typically 5 oz.

      • Weights can be made from different materials.  Zinc and tungsten are the most common and can be purchased specifically for Pinewood Derby cars.  Another good alternative is coins.
      • Position your weights at the rear end of the car, about 1 inch in front of the back axle.
      • Drill holes into the bottom of the car so that you can insert the weights into them. 
      • Use wood putty or glue from a glue gun to fill the holes after you've inserted the weight.
      • Continue adding weights until your car is as close to 5 oz. as possible.  
      • When you weigh the car, put the axles and wheels on the scale also.  If you're adding any embellishments, add those to the scale.  Remember the paint will add some weight, so make sure you account for it.

        Paint and Decorate Your Car

        • You aren't limited to one type of paint for your car.  Enamel or acrylic paints work well.  You can spray paint the car or use a brush.
        • After the first coat, sand the car lightly.
        • When your final coat of paint has dried, add decals, stickers and other embellishments.

        Axles and Wheels

        The axles and wheels of your car can also impact your speed, so follow these steps carefully.

        Lubrication

        Graphite can be used to reduce the friction between the car and the wheels.  Be careful with the graphite, a fine black powder, because it is difficult to clean up. 

        • Start by sanding the axle slots.  Next, add a small amount of graphite to the slots using a Q-tip or your finger.  Continue this process until the slot is covered.
        • Add graphite to the wheel hub until there is a ring around it.  Put graphite into the bore of the wheels.
        • Shake off any loose graphite.

        Axle Installation

        • Pour graphite into the bore as you install the wheel onto the axle.
        • Spin the wheel around the axle, adding more graphite.

        Mounting the Wheels

        • Carefully insert the axles into the axle slots.  They should be positioned as high in the axle slot as they will go.

        Your Pinewood Derby car is complete.  The only thing left to do is win the race!