can you put weights under a pinewood derby car

[DeKhloe]

Yes, you can and absolutely should put weights under a pinewood derby car. In fact, strategically adding weight is the single most important factor in building a competitive car. The official rules typically mandate a maximum weight of 5.0 ounces. The goal is to get your car as close as possible to this limit without going over, as a heavier car has more momentum and potential energy, which translates to faster speeds on the downhill slope of the track.

The key is placement. For maximum speed, you want the car's center of mass (or center of gravity) to be as far back as possible, typically 1 inch or less from the rear axle. This positioning minimizes wheel rotation at the start and allows the car to carry its speed further on the flat section of the track. Always check your specific race's rules for any restrictions on weight type or placement location.

Here are common types of weights used, each with pros and cons:

Weight Type	Pros	Cons	Best For
Tungsten	Very dense, takes up little space	More expensive, harder to cut/shape	Precision placement without altering car design
Lead	Easy to cut and shape, readily available	Health/safety concerns (use gloves), less dense than tungsten	General use, filling larger cavities
Zinc	Safer alternative to lead, decent density	Less dense than lead or tungsten	A good, safe all-around option
Screw-On Weights	Easy to attach and adjust	Can create drag if not flush; may violate "no exterior weight" rules	Quick fixes, but check rules carefully

The process involves drilling holes or carving cavities in the underside of the car body to insert the weights. After gluing them in place, you must re-weigh the car on a precise scale. Use a small amount of putty or removable weights for fine-tuning to hit exactly 5.0 ounces on race day. Remember, the goal is a perfectly weighted, stable car that runs straight.

[VonCaden]

You bet. Getting the weight right is the whole game. Don't just slap it anywhere—drill deep holes right in front of the rear wheels and pack in the heaviest stuff you can find, like tungsten putty. The trick is to make the back end heavy so the front wheels barely touch the track at the start. That reduces friction and lets it fly. Just make sure you’re dead-on 5.0 ounces.

[Camilla]

As a parent who's been through a few derbies with my kids, my main advice is to prioritize safety. We avoid lead weights entirely. Instead, we use small, cylindrical zinc weights that we can safely drill into the wood underneath the car. It’s a cleaner process, and I don’t have to worry about my kids handling dangerous materials. The performance boost from getting to that 5-ounce mark is still huge, and it’s peace of mind for me.

[EliAnn]

Think of it like balancing a seesaw. You want the pivot point (the rear axle) to be just ahead of the heaviest part. This backward weight bias is crucial for speed. I use a tungsten cube epoxied into a carved-out pocket near the rear. Tungsten is ideal because its high density means I don't have to compromise the car's sleek, low-profile design. It's all about maximizing mass in the optimal location without adding aerodynamic drag.

[VanNoah]

My first car was way underweight and it was dead last. Learned my lesson! Now, I start by weighing the unfinished block and wheels, then calculate exactly how much weight I need to add. I drill multiple small holes in the bottom to test different configurations before gluing the weights in permanently. The final step is the most important: fine-tuning with tiny amounts of weight until the scale reads exactly 5.000 ounces. That precision is what separates the winners.