Weights for Pinewood Derby Cars

Most people preparing their car know that the pinewood derby max weight of 5 ounces (141.7 grams). Fewer understand that controlling the weight distribution of the car can make it go much faster. But what most derby enthusiasts do NOT know, however, is that the type of weight actually makes a difference.

What to Use for Pinewood Derby Weights

Traditional pinewood derby car weight options include Lead, Steel, Zinc, and most recently Tungsten. But there are other options such as copper, bronze, or a copper-zinc mix. The below table will help quickly identify options.

MaterialDensity lb./in3Cost/oz.Notes
Brass0.308 (medium)$0.13/oz.Good if in the right shape
Bronze0.318 (medium)$0.16/oz.Good if in the right shape
Copper0.323 (medium)$0.20/oz.Very good and easy to get
Lead0.409 (med-high)$0.05/oz.Heavy but poisonous (wash your hands)
St. Steel0.281 (med-low)$0.02/oz.Good if in the right shape
Tungsten0.700 (very high)$ VariesCosts $5.50/oz finished cylinder retail
Zinc0.258 (med-low)$0.14/oz.Cheap and easy to get

Metal prices can change daily. Above prices are from 10/22/20.

What you want in derby car weights is the highest density material, in the best shape arrangement, for the lowest cost.

Metal Trade Value versus Worth

Regardless of raw metal material cost based on the market (trade exchange), you also need to consider availability of the shape that you want. This will add some cost.

For example, zinc is traded as a metal at $0.14 cents per ounce on the open market. However, casting and packaging costs money. That said; zinc pellets might cost $0.40 per ounce, while flat “snap-off” zinc derby car weight plates average $1.75 per ounce, and zinc cylinders weights are generally close to $2.00 per ounce. That’s a big difference from fourteen cents, but the more convenient it is for the user, the more value or worth it will have.

Why Weight Material Matters – Density

The secret to getting the most speed available out of weights in a derby car is distribution. The more you can control exactly where the weight sits on the car, the more speed you can get (all other things being equal). The trick is to get as much weight into the smallest area possible and pinpoint it as much as you can. Believe it or not, a kid’s joke explains it well…

See also  Pinewood Derby Car Grooved Axles in 2023

There is an old joke that goes “What weighs more, a ton or feathers or a ton of bricks?” The answer, of course, is a ton is a ton regardless of what material is being weighed. The reason a lot of people immediately think the answer has got to be bricks, is because bricks are so much denser than feathers. While it only takes 400 common red clay bricks to equal one ton of weight, it takes about 2,000,000 medium sized feathers to get that same weight. This is the equivalent of about 700 pillows.

Imagine a full-size pickup truck. In the back you can either place a pallet of bricks that takes up only about one-third of the bed and does not go above the sidewalls. Or, you can fill the entire bed with feather pillows, compressing them as much as you can and still have them stick up several feet above the sidewalls under their tarp. Which arrangement offers you more control when trying to pinpoint weight placement? The bricks, of course!

Securing the Weights

One of the Pinewood Derby rules that most standard races follow is that there can be no loose items in, on, or under the car. This is for several reasons.

  1. First, from a safety perspective nobody wants flying projectiles if a car suddenly stops.
  2. Second, if any debris lands on the track it can hinder the performance of other racers – whether in your heat or one upcoming. Something the size of a grain of sand can ruin a race.
  3. And third, some people have tried to arrange sliding or rolling weights inside of hollow spaces in the car’s body in order to try to gain a mechanical advantage.

Regardless of the reason, the bottom line is that all parts (including weights) must be well secured to the car. The Boys Scouts of America PWD website has out “in the box” info at this link if you would like to check it out.

This leaves you with several options: embedding, gluing, mechanically affixing, and sticking. We will look at each.

  • Embedding weights typically means drilling or carving cavities into the body and wedging the weight in place. The weight is also often glued in if there is a reasonable chance of it becoming dislodged during the race. The officials will make this call, so if you have any such weights bring along a tube of Crazy Glue.
  • Gluing weights can be done to ensure embedded weights don’t pop out as mentioned above.  Gluing is also a great way to affix weight to any of the car’s surfaces.
  • Mechanically affixing is a just a way to cover all methods of nailing, screwing, pegging, etc. Depending on your local official’s interpretation of the rules, this could potentially include using wire to hold a weight in place or even coiling a bunch as a weight in itself. It would just need to be properly crimped, tied, or soldered into place.
  • Sticking is one of the easiest and most flexible ways to mount weights anywhere on the car you wish. Many pre-shaped weights even come with one surface glued so you can simply peel off the slick paper glue cover and stick it into place. Just keep in mind the race officials might give any such weights a tug to make sure they are secure before allowing the car to race.
See also  How do you remove burrs from pinewood derby axles?

Last Minute Weight Tweaking

Even if you have the most accurate scale in the world, it might not give identical measures as the scale being used at the official derby weigh-in. For this reason, it’s nice to have options to maximize weight and distribution at race time.

Remember: The judge’s scale gives the official car weight – even if it’s not technically correct.

Knowing that any scale can be a tiny bit off, here’s a little insurance policy you can use if you are a die-hard racer looking for every possible advantage…

Add a small dimple or shallow hole to the back of the car, either on the top or rear bumper area. Build the car to be just under 5 ounces by using carefully affixed weights. Get the car to 5 oz. (141.74 g) by filling the small hole with tungsten putty. The putty should stay in place, but you should cover it with a decal to be sure.

Above is the rear of car with small hole filled with tungsten putty. About one-tenth of an ounce of putty should be fine. You can drill the hole a bit larger than needed in case your car weighs in light and the judges give you a chance to maximize your weight to the allotted 5 oz.

Using a decal that you can reapply is best in case you need to remove it. However, you can also just bring a separate decal and replace it as needed.

Making Derby Weight

If, for any reason, your car registers over 5 ounces simply remove a tiny bit of the putty. As long as it is securely in or on the car you should be fine. Although you should always check with the officials of your local event first.

See also  Pinewood Derby Weight Placement

Typically, you will bring your pinewood derby car to the judge’s station for official weigh-in and inspection well before your race heat begins. If they find an issue you can try to correct it within an allotted time. This includes “making weight.”

Once your car has had its final weigh-in and inspection (and passed) the officials will take it and be the only ones to handle it until race time.

Note: Tungsten putty is non-toxic and can be shaped like “Silly Putty” for the most part. It does not harden so this makes it ideal as a last-minute way to add or subtract weight from your car. It costs about $8 per ounce, but you should only need a tiny amount and may be able to buy a smaller quantity or split it with friends.

Want a hack to weight your car for about 30 cents? While tungsten cylinder weights cost an average of $5.50 per ounce, you can get the same weight for just $0.10 by using everyday coins.

Weight Placement on the Car

As mentioned, the (weight related) trick to squeezing every last millisecond from your track run is about optimal weight placement (IE/ distribution).

This is where it gets a bit trickier than simply placing weights at random until the magic number of five ounces has been met. We need to understand center of gravity, car design, and even wheel placement such as standard spacing, extended and/or having one wheel raised.

That said, the topic of specific weight placement deserves an entire post of its own. You can also check the youtube video below-

I hope you like reading on Weights for Pinewood Derby Cars.

Last update on 2023-10-26 / Affiliate links / Images from Amazon Product Advertising API