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How to add weight to a Street Car Pinewood Derby Car
The heavier your pinewood derby car, the faster it will go. Most race rules limit the weight to 5 oz so you want your car as close to the limit as possible. The Street Car block will need about 2.8 oz of additional weight to bring it up to the 5 oz limit.
You should install the weights in your car before you paint it.
Before adding the weights to your car, put the car block, wheels, axles and any other accessories that you will be adding to your car on a scale. Then add the weights until the total is 5 oz. (paint will add very little to the weight of your car).
When your car is complete, weigh it again. If it is over 5 oz, drill a few holes in the bottom of the block about an inch behind the front axle to remove some wood.
Below are two suggestions for adding weights to your pinewood derby car.
Lead Wire Weights
Lead is inexpensive, dense and is easy to work with but lead is toxic. Always use gloves when working with lead and make sure that none of the lead is exposed after you install it in the block.
After determining the amount of weight needed by weighing the car and weights, cut two weights that are approximately 1 3/8", 3 at 1/2" then cut the remaining weight in three equal lengths. You can cut the weights with a hack saw, coping saw or wire cutters.
You will need:
- One set of Lead Wire Weights
- Drill and 5/16" drill bit
- Wood putty
- Sandpaper
- Hack saw, coping saw or wire cutters
- Using a 5/16" drill bit, drill two holes in the side of the car, one behind the rear axle and one above the rear axle. The depth of these holes should be slightly deeper than the length of the 1 3/8" weights.
- Drill three holes in the bottom of the block parallel to and in front of the rear axle. These holes should be slightly more than 1/2" deep. Position the holes so that you will not drill through the top of the car.
- Drill three more holes in the bottom of the car in front of the previous set of holes. These holes should be deep enough for the remaining weights..
- Insert the weights in the holes. The end of each weight should be at least 1/8" into the end of the block. This will leave room for the wood putty. Drill the holes deeper if needed.
- Weigh the block, wheels, axles and weights again. Adjust the amount of weight if needed for 5 oz.
- Seal the weight holes with wood putty. Allow to dry in a warm place for 12 hours.
- Sand the wood putty until smooth and flush with the car block.
You can now paint your car and add the wheels and axles.
If the completed car is less than 5 oz. drill one or more shallow holes in the bottom of the car in front of the other weights and insert some of the leftover lead weight in the holes. Seal with wood putty.
Tungsten Weights
Tungsten is very dense but it is more expensive than the other weights. The density gives you a speed advantage because more of the weight can be placed farther back on the car.
Use a combination of cylinders and plates for optimum results.
You will need:
- Six Tungsten Cylinders
- Two Tungsten Plates
- One Fine Tune Cylinder
- Drill and 3/8" drill bit
- Screw driver
- Using a 3/8" drill bit, drill three holes 1/4" into the bottom of the block behind the rear axle. These holes will be close together so start the holes with a small bit or use our Weight Guide. If you will be using some of the Fine Tune Cylinder weight, drill these holes a little deeper to hold this weight in addition to the Tungsten Cylinders
- Drill three more hole just in front of the rear axle. Drill these deep enough to hold one cylinder each plus any additional Fine Tune weight. The Fine Tune Cylinder can be cut with a scissors or knife.
- Insert the weights in the holes. The end of the weights should be flush with the bottom of the block.
- Weigh the block, wheels, axles and weights again. Adjust the amount of weight if needed with the Fine Tune Cylinder.
- Attach the two Tungsten Plates to the bottom of the block with the included screws. Place one plate as far to the rear of the car as possible so that the plate screw will miss the center cylinder. The plate should at least partially cover the cylinders to keep them in place. Place the other plate in front of the rear axle so that the screw is just in front of the center cylinder weight and the plate covers at least part of the cylinders.
- Paint your car and add the wheels and axles.