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How to add weight to our Comet Pinewood Derby Car
Your pinewood derby car should weigh 5 oz. when conpleted. This means that you will have to add weight to your car. The Comet block will need about 2.5 oz of additional weight to bring it up to 5 oz. Install the weights in your car before you paint it.
The first thing that you should do is weigh the block, and everytning else that will go on your car. Add enough weights until the total is 5 oz.
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 the comet pinewood derby car.
Lead Wire Weights
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.
When weighing the car and weights, cut the weights 1 3/8" long. If you need shorter weights to bring your car to the 5 oz limt, cut them 1/4" long. 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
Side View
Bottom View
- Clamp the car block on a flat surface.
- Using a 5/16" drill bit, drill the same number of holes as you have full length weights straight in the side of the car starting with one hole behind the rear axle and the other holes in front of the rear axle. The holes should be about 1/2 inch apart. Drill to 3/16" of the other side of the block but be careful to not drill all the way through.
- Remove the clamp from the block.
- Drill holes for the shorter weights in the bottom of the block in front of the other holes. Be careful to not drill all the way through the block.
- Insert the weights in the holes. The end of the weights should be at least 1/8 inch in from the side of the block.This will leave room for the wood putty. Drill the holes slightly deeper if needed.
- Weigh the block, wheels, axles and weights again. If you need to add more weight, drill another hole in the bottom of the block.
- Install the weights in the block and seal the weight holes with the 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 hole in the bottom of the car in front of the other weights and insert some of the leftover lead weight in the holes.
Tungsten Weights
Tungsten is very dense but it is more expensive than lead. 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 a flat plate for optimum results.
You will need:
- Eight 1/4 oz Tungsten Cylinders
- Tungsten Plate
- Fine Tune Cylinder
- Drill and 3/8" drill bit
- Wood putty
- Sandpaper
- Screw driver
- Using a 3/8" drill bit, drill two holes side by side into the bottom of the car behind the rear axle. Drill just deep enough to hold one 1/4 oz weight each. The end of each weight should be flush with the bottom of the block (these weights will be held in place by the tungsten plate that will be mounted on the bottom of the block).
- Drill a hole in the center of the block just in front of the rear axle. This hole should be deep enough to hold two 1/4 oz cylinders.
- Drill another hole in front of the last hole. Drill this hole deep enough for three 1/4 oz cylinders. If needed, drill holes for the remaining cylinders in front of the other holes. The ends of the cylinders in these last four holes should be in 1/8" from the bottom of the block. This will leave room for the wood putty. You may need to tap the cylinders into the holes with a small hammer.
- Weigh the block, wheels, axles and weights again . Adjust the amount of weight if needed by adding part of the Fine Tune Weight in a hole in front of the other holes.
- Insert all the weights in the holes and fill the weight holes with the wood putty. Do not use the putty on the weight behind the axle. Allow to dry in a warm place for 12 hours.
- Sand the wood putty until smooth and flush with the car block.
- Paint your car and add the wheels and axles.
- Attach the two plates to the bottom of the car using the supplied screws. One plate should go behind the rear axle and right under the two cylinders. The second plate should be placed in front of the rear axle and between the cylinder holes so that the screw will go into the wood and not the putty.