Pinewood Derby Notes for Dads

I. THE PLAN
II. SPEED/WINNING
III. LOOKING COOL
IV. RACE DAY REMINDERS

THE PLAN
From the very beginning, you should talk with your son about HIS goals for the car. What is most important? Usually it’s “looking cool” or “speed/winning”. Both are worthy goals but are often mutually exclusive. I encourage you to clearly identify which he wants and focus on that. When he says “both”, try to pin him down to one or the other. Begin with the end in mind and you’ll both be happier. Check your Pack’s rules from the very beginning and be sure you are following them closely.

Based on those two possible goals, these notes are designed to guide you through the various steps of helping you and your son make that naked block of wood into something of which he will feel proud. If you’re on the “looking cool” track, feel free to incorporate as many of the tips from the “speed/winning” section. Please recognize and set expectations that even if you do ALL of the things listed, someone else will probably do it better. Talk with your son about a great standard of measure for this project that is also the Cub Scout Motto: “Do your best.” That’s all you can do.

Scout participation is something you likely will need to develop a strategy for. I never worked on the car without John being out in the garage with me. He designed the car all by himself and helped drill, paint, weight, and mount the wheels. We mutually had no interest in him operating any machinery. Someone could probably gripe at me since I made the cuts, etc. but we really did work hard to make this HIS car. I believe we honored the spirit and intent of the race and the rules.

SPEED/WINNING
1. If pure speed/winning is your primary objective, don’t start out with a hot wheel as your model. Understand that your “car” won’t look much like a car at all. Read this through; I suggest preparing for wheel mounting before you start cutting on the block.
2. Aerodynamics. Keep a low profile. There are some designs online that are called “modified rail” and other things that make the body sturdy enough to handle the impact at the end of the race into a block of foam (or whatever), but sleek enough to reduce drag. Aerodynamics’ influence in the Pinewood Derby likely affect speed in hundredths of seconds, but probably not tenths of seconds.
3. Design.
a. Essentially you’re going for something that is ½” - ¾”, maybe a bit more in diameter with wings that hold the wheels at the right distance apart. Maybe it tapers to be thicker in the back to accommodate a place for the weight. I’ve never helped build a car with this shape, so I can’t really speak from experience. John & I worked from a goal of wanting a certain look AND speed. What is described here appears to be the most effective design.
b. Short of a rail, you want flat or with a slight angle higher in the back, but not much. Use a band saw, table saw, Dremel or hand tools to create the desired shape.
4. Wheel Base. Expand the wheels out as far as you can on the length of the car. Most Packs have the rule that you can’t make the car LONGER than the block that you start with. We put the wheels next to the block and marked where we were going to drill for the axles. Ignore those slots cut in the bottom, just fill those in with wood filler after you cut out the shape.. I’ve read this elsewhere where people who are smarter than me have said this makes the car go faster. I believe them and take this at face value so as to not hurt my brain thinking about it. NOTE: We’re talking about making the distance between the front and back wheels as much as possible. The width is predetermined by the tracks.
5. Weight. Goes as far back as possible. The weight is then acting on the most mass of the car. Again, I read this online and it makes sense. We used a soldiering iron and lead for weight. First we cut a hole underneath the car with a forstner bit (or spade bit if you have that) to create a well for the lead. Then we melted lead into the hole with a scale nearby. This method allows you to control the weight and then drill out of the car is too heavy. There is an aerodynamic element here – John & I drilled out too large of a hole making the underneath of the car less aerodynamic – who knows what the actual impact of that was, but I suppose every bit helps. Next time, we would have put a piece of tape over the hole. I recommend that you show up on race day with your car just a little too heavy, so you can adjust your car to the official scale. You want your car as heavy as you can make it, right up to the 5.00 ounce limit.
6. Axles.
a. Mount them on a drill or drill press and using a file to carefully remove the little burr on the nail and on the underneath side of the nail head. Start with a file, then use 150, 220, 400 (and higher) sand paper then 0000 Steel wool and finally chrome polish with a rag. This is the most time consuming of the whole thing but you have to get the burrs off to reduce friction and then re-polish the axle.
b. Put graphite on the wheels before raceday. Sometimes stuff happens and you forget or you’re running late. The things you do to mount the wheels and prep the axles probably matter more than anything else.
7. Paint. Spray paint is best because it’s already shiny. If you use acrylic or brushed paint, consider a glossy spray overcoat.
8. Decals, etc. You can print off anything you want from the internet, but stickers really are better. You can get model stickers, etc. The Scout Service Center has some new & cool decals, but also Michaels, Hobby Lobby and the like sell stickers that seem specifically made for Pinewood Derby.
9. High gloss overspray. We tried this because John wanted a picture of Darth Maul on his car, which we printed off online and glued to the car. When we did it the first time, the gloss spray made the other spray paint run. Use caution and get this done with enough time in case you need to strip it and start over (like we did.)
10. Wheels. By rule, you can’t modify the wheels other than take the very small bump off that is a result of the manufacturing process. I’ve never messed with that too much (but work around it by wheel mounting). The logic here is they don’t want you cutting the wheel and changing the original wheel profile of: ┌────┐ to look like: ┌──┴──┐ where there is a slight extension or burr sticking out from the wheels all the way around; that way the car is riding on just that small edge, creating less friction.
11. Wheel mounting. Start thinking about this first thing out of the box. The goal is to mount the axles at an angle of 4-7 degrees, enough so that when the car runs, it’s running on the inside edge of the wheel, not the whole flat surface. Additionally, my theory is this keeps the wheel riding against the nailhead instead of against the car. One of the Dads in our pack expressed concern about this technique saying it wasn’t fair. The Pack’s logic is that policing this is too hard, so don’t speak to it in the rules. My belief is this technique might buy you tenths of seconds and is very much worth the effort. To actually do this, we just used some wedges leftover from some tapered cuts I’d made previously and used those to hold the block at the correct angle (no magic number here.) Standing in front of the drill press, you want the top of the car facing you and for the car to tip slightly away from you. Pre-drill holes first thing for the axles before you do any other cuts in the block. Consult your Pack’s Pinewood Derby rules before deciding what to do here.
12. Once it’s done, put it away. Find a box or some other conveyance that you’ll use to get it to the race. It would be a shame for something to happen to the car.


LOOKING COOL
This is great. Most Packs give awards for this and all should. Let your son dictate what he wants to do; you help him excel in the direction he wants to go.
You must use the original block, don’t forget. There were some boys who built fenders around the wheels of their cars and they did it with the wood from the original block – no easy challenge.

The world is your oyster – you can make it look like anything. Some of the designs I’ve seen live or online include:
Pencils Yoda surfing on a log Canoes & other boats
Skateboards Jet fighter plane fish
Toothpaste tubes Tanks & various military baseball bats

Really the sky (or the block of wood) is the limit.

RACEDAY REMINDERS:
1. Graphite the wheels before you leave the house, if possible.
2. Registration is a little strict with our Pack, so once you officially register your car, you can’t touch it for any reason. We offered a pit stop area where cars that didn’t pass or needed some help before registering could get it.
3. Volunteer to help – your Pack will have a thousand jobs that need to get done.
4. Pep talk. Remind your son about all the work you did together, how much fun you had making the car and that you did your very best – which is all you can do.
5. Have a great time!