7 Steps to Build a Faster Pinewood Derby Car (2024)

For 70 years, Scouts and their dads (or is it the other way around?) have been building Pinewood Derby cars from a block of wood, four wheels, and nails used for axles. In that time over 100 million Pinewood Derby Car kits have been sold. The race is an event Scouts and their parents look forward to each year, with winners moving on to district or regional competitions.

In December, my son’s Cub Scout pack announced that their Pinewood Derby race would be scheduled in February. So, it was time to start planning our car—I say our car, because it is expected to be a collaborative project between a parent and their scout. During the process we discussed various options, and priorities, but I left the final decisions up to him. When it came to power tools, I used the table saw, while he was able to help with the hand drill and drill press. Sanding, priming, and painting were things he was able to do with some instruction. He ultimately ended up with a car he’s very proud of and is eagerly awaiting competition.

How the Pinewood Derby Works

The Pinewood Derby is a gravity race held on a straight, multi-lane track. Each car’s wheels straddle a wide rail that keeps it from coming into contact with other cars. Starting at a height around four feet, the track runs downhill and transitions to a flat run-out on the floor. The total length may vary by track, but they are usually about 32 feet long. Tracks have a starting gate that releases all cars at the same time. Each Scout Pack or District may run their races a little differently, but each car usually runs a heat in each lane. Timing is typically done electronically to determine placing, and a system of elimination is used to advance winning cars.

The Rules

I was surprised how simple the Pinewood Derby Rules actually are. There are only nine rules, included here, from the Sountshop.org website:

  1. Width shall not exceed 2-3/4 inches.
  2. Length shall not exceed 7 inches.
  3. Weight shall not exceed 5 ounces.
  4. Axles, wheels, and body shall be from the materials provided in the kit. Additional wheels can be purchased separately.
  5. Wheel bearings, washers, and bushings are prohibited.
  6. No lubricating oil may be used. Axles may be lubricated with powdered graphite or silicone.
  7. The car shall not ride on any kind of spring.
  8. The car must be free-wheeling, with no starting devices.
  9. No loose materials of any kind are allowed in the car.

These leave a lot of leeway in what can be done to a car—or so I thought. Before you start on a Pinewood Derby Car with your child, check to see if their Scout Pack has any additional rules. I discovered our pack’s rules are several pages long. This is actually good, though, as it ensures a fair race where kids like mine, with a parent experienced at making things, doesn’t have too big of an advantage.

The Question Every Parent Wants to Know:
How Can We Build a Fast Pinewood Derby Car?

I had some ideas about what we needed to do, but with this question in mind, I began some research. There is no shortage of tips and tricks on the internet and it can be difficult to vet each one and figure out which actually work, and which are a waste of time. Fortunately, I found a YouTube video by Mark Rober, which does exactly that. If you are unfamiliar with Mark, he’s a former NASA engineer responsible for the Glitter Bomb vs. Porch Pirates videos.

In his Pinewood Derby Car video, Mark expands on research done by Dr. Scott Acton, who used scientific methods to test all sorts of car characteristics, and determine which variations worked best. Mark also identified a couple characteristics Dr. Acton didn’t investigate, and came up with this simple list of seven steps to build a fast Pinewood Derby Car. I’ve listed them here in the order you would need to do them when building your car, but I’ve ranked them by importance in parenthesis:

  1. Simple aerodynamic shape (3rd)
  2. Lightened wheels (2nd)
  3. Polish and bend axles 2.5 degrees(4th)
  4. Raise one wheel (5th)
  5. Align wheel to ride lane rail (6th)
  6. Maximize allowable weight (1st)
  7. Use lots of graphite lubricant (7th)

Note that these features and modifications are all allowable within the official rules but may not be allowed by your Scout Pack’s rules. Our Pack, for example, doesn’t allow modifications to wheels, nor bent or machined axles.

Step-by-Step Instructions

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This is a basic Pinewood Derby car, built with the seven characteristics we outline below.

While this care doesn’t look fancy, it has the characteristics most common in the fastest cars. It also doesn’t take a much time or a lot of special skills to build. Bear in mind, there are all sorts of aftermarket parts designed to help make your car faster. But, in keeping with the spirit of the rules, these instructions, and the car we built here, use only the parts contained in the Pinewood Derby Car kit. Scouts are usually provided one kit by their pack, but you can also buy kits from Amazon.com or ScoutShop.org.

Step 1: Aerodynamic Shape

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A body blank (left), and a second blank cut to make a5/8-inch high body.

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We rounded off the front of the body, but you could just as easily cut it at a 45-degree angle.

You can make any aerodynamic shape you want, but it doesn’t need to complicated. You just need to minimize the frontal area. A long, flat slab or shallow wedge will do that. We used a table saw to cut the body down to 5/8-inch tall slab and then rounded off the front so the air would slip over it more easily.

Step 2: Lighten wheels

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A stock, official Pinewood Derby wheel.

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Using sandpaper to remove material from the sidewall of the wheel.

A small lathe is the ideal tool for lightening wheels. However, you can do it with a basic hand drill. The key is to remove some material from the sidewall and tread. By lightening the outside edge of the wheel it is able to spin up to speed quicker when the car starts rolling down the track.

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Removing material from the tread.

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The modified wheel with material removed from the sidewall and tread.

Step 3: Polish and Bend Axles

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Polished axle (left), compared to a stock axle (right).

You can buy polished axles, as well as bent and polished axles for your pinewood derby car, but we chose to stick with the ones that came in the kit. The stock axles are really just nails, and they are usually pretty rough. Again, a lathe is the best tool for the job, but we had great results using a hand drill, needle files, some sandpaper, and polish.

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Stock axles have ridges and burrs that cause unnecessary friction.

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A flat needle file can be used to smooth out the bottom of the axle head.

Start by putting the axle into the drill chuck, about 1/4 inch and tightening it. Wrap an elastic band around the drill handle, and pull it up over the trigger to keep it on while you work. With the drill running, use the flat side of a needle file to file to smooth out the bottom of the nail head. The goal is to remove the two tabs that stick out and make it flat. Then flip the file 90-degrees and smooth out any rough areas on the nail shaft.

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Wet sand the axle to remove the file marks.

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Polish the axle with compound and a rag to finish up.

Next, wet sand the axle with strips of sandpaper. We used three grits, starting at 400, then 600, and finally 1000. Finish by polishing the axle with compound on a rag to make it nice and shiny.

The next step is normally bending the axles up, to 2.5 degrees which gives the wheels negative camber. This causes them to tilt toward the body at the top, so that the wheel migrates to the end of the axle, away from the car. There is less friction when the wheel spins against the nail head than when it bounces back and forth between the head and the body. If you chose to do this modification, this handy tool will help bend axles perfectly, every time. Our pack rules prohibit bent axles, but there is still a way to angle straight axles up, at 2.5 degrees, which is what we did.

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This jig can be used to drill angled holes for straight axles.

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Lining up the axle slot on the car body with the hole in the jig

We used a jig to drill guide holes in the axle slots, at a 2.5-degree angle, which accomplishes the same thing as bending the axles. The jig can also be used to drill a straight, level hole, as well as a raised hole to lift one wheel off the track—more on that in step 4.

Line up one of the outside holes on the jig, where you what to position your axle—our rules hold us to the stock wheelbase, so we lined it up on the rear axle slots. Squeeze the jig tight to the body and use a screwdriver to tighten it. Then use the drill bit supplied to drill holes on each side of the car body.

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Use a drill in the the outside hole in the jig to make an angled axle hole.

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The end result should have both wheels angled toward the body at the top.

Step 4: Raise One Wheel

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Drilling a hole above the left, front axle slot will keep the wheel raised off the track.

Raising one front wheel, so that your car rides on three wheels will make it go faster. With one less wheel, the amount of energy needed to spin wheels up to speed is reduced by 25 percent. The typical way to raise one wheel is to use a saw and make the axle slot in the body deeper. However, the jig we used to drill the angled axle holes, also has the option to drill a high axle hole.

Step 5: Align Wheel to Ride Lane Rail

A typical Pinewood Derby car will wander from left to right, bumping into the rail between its wheels, as it runs down the track. These bumps cause friction and rob the car of speed. Aligning the right front wheel to steer the car gently into the rail actually creates less friction. If you’re using bent axles, you can use a pair of pliers to grab the head of the axle and rotate it forward to make the car turn left. You can lay a 5 foot strip of tape on the floor to check the alignment. Over that distance the car should only deviate about one inch from that line.

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Using tape to shim the axle hole jig.

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Drilling the right, front axle hole on an angle, so the car will gently steer to the right, into the rail.

If you’re using straight axles, the only way to align that front right wheel, is to drill the axle hole on an angle. Through trial and error, we found a way to shim the jig to a suitable angle. On opposite edges of the jig we placed three laters of painter’s tape, so that when clamped to the body, the jig was no longer perpendicular to it. Drill the hole as shown in the photos above and be sure your tape is to the rear of the jig, on the right side.

Step 6: Maximize Allowable Weight

Maxing out your car’s weight is one of the most important steps in building it. More weight means more potential energy to push the car down the slope. Weight is one thing that is not included in your car kit. You can get creative and add just about anything you want for weight.

Pennies are about the most cost effective weight, but they take up a fair amount of room, so it may be difficult to locate them exactly where you want. We bought 4 ounces of tungsten weights for our car because they are dense and pack to most amount of weight, in a small area.

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Center your weight 1-inch in front of the rear axle.

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Check the weight of your car by putting all of the parts on a digital scale.

Your car’s center of mass should be just in front of the rear axle. Measure and mark a line, 1-inch in front of the rear axle slot. Put your car body, wheels, and axles on a scale, then add weights until you hit 5 ounces.

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Outline the area to the needs to be removed to embed the weights.

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Create a pocket where you can glue the weights in the body.

Center your weights over the line in front of the axle and draw a line around them. You’ll need to create a pocket where you can secure the weights. The easiest way to hollow out this area is with a small Forstner drill bit, on a drill press. Set the depth deep enough for your weights, without drilling all the way through your car body. Once you have the area roughed out, clean up the edges by hand, with a chisel.

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Smear epoxy in the bottom of thepocket.

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Press your weights into the epoxy.

Mix up some 2-part epoxy to glue your weights in the pocket—we used JB Weld. Spread a little in the bottom of the pocket, and then carefully install your weights, pressing them down so they don’t protrude below the bottom of the car body.

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Fill the pocket with epoxy, covering the weights.

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Weigh your car and add small screws to get as close to 5 ounces as possible. We got to 4.98 ounces, which gives us a little cushion for paint.

Spread more epoxy over the top of the weights, all the way to edges of the pocket. You can use a popsicle stick to scrape over the top of the area so that the epoxy is level with the car body. When the epoxy dries you can sand off any high spots. Put all the parts for your car back on the scale—the weight may have dropped a little due to the wood removed for the weights. Add 1/4 to 3/8-inch wood screws to get as close to 5 ounces as possible. We came up .02 ounces under.

Step 7: Use Lots of Graphite Lubricant

The last step, aside from paint, is to lubricate and install your wheels and axles. Dry lubricants are generally the only type allowed in Pinewood Derby racing, with graphite powder being the most popular. Use plenty!

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Apply graphite to each wheel and axle before you install them.

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A scrap of sheet metal can be used to make a wheel spacing tool like this.

Squirt some graphite into both sides of each wheel before inserting the axle. When you’re ready to press the axle into the body, use a wheel spacer tool to be sure you don’t install it too tightly. While you can buy the tool, we quickly made one out of a scrap of metal. Keeping the tool between the body and wheel ensures you leave enough space to allow the wheel to turn freely.

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Pressing the axle into place.

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There should be a gap between the wheel and the car body.

Once the axle is pressed in, remove the spacer tool and make sure there is a suitable gap between the body and wheel. Once they’re all installed, you’re ready to race—and win.

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Bradley Ford

Test Editor

Brad Ford has spent most of his life using tools to fix, build, or make things. Growing up he worked on a farm, where he learned to weld, repair, and paint equipment. From the farm he went to work at a classic car dealer, repairing and servicing Rolls Royces, Bentleys, and Jaguars. Today, when he's not testing tools or writing for Popular Mechanics, he's busy keeping up with the projects at his old farmhouse in eastern Pennsylvania.

7 Steps to Build a Faster Pinewood Derby Car (2024)


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