Cub Scout Pinewood Car Derby

[alf]

I was not a scout in the US when I was a kid and do not have the experience to build a winning car for my 2 boys in their upcoming derby. Anyone got any tips to share?

[Don Plumley]

Chuck the nails in a vise and sand them smooth.
Ditto on the wheels.
Use dry powdered graphite on the wheels.
Take the weight right up to the limit - but try to get access to the official scale.
Don't put the car in the toaster oven to speed the drying of the paint...

[Gooch1971]

Do an internet search. There are tons of sites with tips and speed parts available for sale.

[Porsche-poor]

be sure and check your local rules. In my pack if the wheels have been sanded smooth your out. Get to the 5oz weight on hte dot, if your under it will be slow.

[alf]

Originally Posted by Gooch1971

Do an internet search. There are tons of sites with tips and speed parts available for sale.

wow, I just did. There is a whole cottage industry around this! Amazing. I am not going to go that far, this year Just the basic kit and stuff in my garage to make it work.

Keep the secrets coming!

[p911dad]

I have fond memories of the annual Pinewood competition. Like Don says, use the graphite and I would add, make sure the kids have a major role in the design and execution.

[Chuck Moreland]

Best tip: make sure both Son and Dad are involved.

As a kid, I recall some cars were beautifully turned out with all the skill dad could muster.

My cars looked like a kid built them. I did all the work with some direction from dad.

I never won. Yet, I think I learned more than the kids whose dad's built their cars.

[flashgordon13]

Polish the axles and use graphite as mentioned. Making sure the wheels turn freely without excess woble is key. There does need to be a small amount of wobble in the wheels for the car to run freely. This is part of the art of building one of these thing to win. Another trick is to apply some graphite on the sidewalls of the tires to reduce friction when the tires touch the guides on the track. There is much debate on where to place the weight. Placing the weight in the rear of the car helps on tracks that level off before the finish. Placing the weight in the front of the car is better on tracks with a steady grade right to the finish. Body shape seems to play no real role in performance, so you can let your son preety much do as he pleases in this area. Painting and decorations are a top priority with boys, so spend some time with your son planning the apearance. The most important thing is to enjoy the time building the car and don't worry about the results. Have fun and good luck.

[Dave L]

I laughed when I looked at my Cub Cars when I was at home last time. I can see the steady progression from when my dad helped me do the whole thing to the last year when I did all the work myself. The first car was beautifully carved and painted the last car was crude to say the least and was mostly "sculpted" with a hammer and dull chisel.

I think the real way to "win" is to spend time with your son designing, planning and working on it.

[bell]

i've built a few, i like to have the wheels cambered in a little, so they ride on the inside edges, simply put the nail/axle in at a slight angle to achieve this. i also like them to "3 wheel" meaning to have one rear wheel not touching at all.
i bring the weight up with lead fishing bobbers melted into place (i use sheet metal with vice grips for a handle, bent into a triangle so it can be poured easily) heat it from the bottom til it melts and pour. watch the fumes they aren't good for you.
lasty put the wheels on last, this way if your son plays with it it won't hurt the axles and his chance of winning
the last 4 cars i've built have always finished in the top 2.........for my boss' kid

[tcar]

Pinewood derby is a joke. Kids are supposed to build them, or at least they were a few years ago.

My 2 kids built their own, w/ my input and guidance. I think out of about 30 cars, only about 4 of them were.

Some looked like they came out of a Penske shop.

No one seems to say anything when the kid runs a car he has never even touched or seen before.

Terrible. IMO.

[89911]

My son and I won the whole thing a few years ago (out of about 120 entrants). The first 2 years we weren't even close. I must of spent maybe 2-3 hours max on the one that won. The last poster was completely correct in that it is all the Dad's work and none of the child's. (See comment above about the first 2 years). So we did the "sharing the build" stuff for the first two years and I am sure he enjoyed it. The year we won, he didn't even really care because of the other poor outcomes, so I figured I would try to win it for him. I really think that after you get a few things right, there is a lot of luck involved. A couple of key points: Keep your kids hands away from the project, he'll only mess it up Make sure the weight is as close to 5 oz as possible. If you don't have a scale, borrow one or buy it. Most cases, they will let you check it on weigh in, but it still needs to be close. Better to be slightly heavy and drill out the weight then add. Polish the nails so the axles have no burrs. Used powdered graphite. If you have a drill press, pre-drill all the axles before you shape the car. Give them a few degree's of negative camber evenly to all the wheels. You can have two cars that roll straight, but one can be rolling freely and another can be fighting itself with wheels that may have caster angles not perfect straight. Yadda yadda yadda. Internet searches will turn up a lot of this.


My son Kyle and me. He is no longer involved with scouting. It was fun for a while, but I found the whole thing a bit "forced". The parents sat around and talked the whole time while the kids mostly ran around unsupervised. I have more interaction with my son watching "The Simpsons". Hopefully your experience will be better. I am joking also about keeping you kid away from the project. If you want to compromise, let him do the design and painting, you do the mechanicals. Good Luck.

[charlesbahn]

I used a belt sander to help the kids shape their cars however they wanted and they did all the rest. It was a hoot. The ugliest cars usually did the best. My son's car, named "Axyl Rose" decorated with hole punch protectors had "eat my sawdust" written on it and actually did pretty well.

The key is to let the kids have fun, and they will. They just won't win.

[alf]

I am going to leave the body to the boys but I just spent 3 hours polishing and slotting the nails, umm axles. While the boys sanded away.

We are all covered in dust and i have saw marks on my left hand.

Brother in law (who was an Eagle Scout and 3x veteran of the sand box) coming over tomorrow to help paint and finish.

[jluetjen]

Thinks haven't changed much since 35 years ago when I did it with my Dad. The same tricks worked for me then that people are saying now. I won the pack, was 2nd in the town and 1st in the region. The only other trick that I seem to also remember is to put the ballast in the back.

More importantly, given that I'm now a parent -- I think that the first thing is to agree on the goals with the scout. Do you want to win? Look good? Have fun? By the way, I mean what the scout's goals, not ours. Once that's figured out, try to accomplish the goal first and foremost, while doing the best that you and the scout can. If you build a winning car and the scout doesn't care -- who cares??? If you come in 5th, but your scout always remembers the experience in a positive way -- you'll have a life-long memory.

[David]

I always put the weight in the back since potential energy = mass * gravity * height. Mass is limited, gravity is constant, so only height can be maximized. Putting the weight in the back allows the weight to fall the farthest. This assumes the track flattens out before the finish line.

Some tips:
Sharpen the wheel hubs where they contact the body.
Put the axles in a drill press, file off the ridges and make the backside of the head cone shaped so less of the head contacts the wheel. Then polish to mirror finish.
Make it a three wheeler, with one front wheel off the ground.
Don't use the stock axle locations (if allowed), put the wheels at the far ends of the car so it'll track straighter. I flip the block over so the original axle slots are cut off.
And most important, make sure it rolls straight when it's not on the rail.

Our local district has classes for kids and adults, so if dad's wanted to go all out they could without competing against kids.

[red-beard]

This only helps if the track has a starting gate with a slot in the track and the stick drops into the track. Make the nose very high and slant from front to back from top to bottom. This way as the starting stick drops, the nose slips forward. My first racer was accidentally built this way. My seconds racer was built around this.

[Mo_Gearhead]

All these 'tricks' reminds me of the similar 'full size' (kids inside) Derby races.

I guess they used to use metal 'stops' (held the car in place at the top of the hill, then fell away to start the race). A clever guy (and his kid?) put a electromagnet/battery in the nose of the kids car. Video tape of every race he was in showed the car launch like a scalded cat as the falling steel plate pulled the front of the car forward as it fell. Amusing stuff.

Isn't it supposed to about the kid getting some life experience?

(gee dad ...is this cheating?) Duh.

[Jeff]

Originally Posted by Chuck Moreland

Best tip: make sure both Son and Dad are involved.

As a kid, I recall some cars were beautifully turned out with all the skill dad could muster.

My cars looked like a kid built them. I did all the work with some direction from dad.

I never won. Yet, I think I learned more than the kids whose dad's built their cars.

Most important statement here!

Also, Paint it in the Porsche Gulf Blue style.

[89911]

Weight in the back, good! Exactly as the poster said. Think of it this way. At the start of the race everything is equal. When the car hits the level portion coming from the incline, the weight in the back will fall even farther, using more of the stored potential energy. I designed all the cars this way. The one that won was usually even coming down the hill and it then took off as soon as it hit the straight. 3 axles also good. You are using less energy rolling 3 instead of 4 wheels. New axles locations good. I drilled the car with new axles on a drill press at the same distance as the originals.


The way the track is devised also has a lot to do with it. His den ran a 6 lane run off and a time was taken for 6 runs in each different lane. They then took the top times and had a seeded elimination. Very well run and organized. When He went to the district finals, it was a double elimination on a 2 lane, poorly made track. You could have the 2nd fastest car and not even place if you come against the fastest one in your first heat. Notice how the first track is primarily flat. Cars with weight in the back seem to do much better here. On the steeper, shorter course, it made less of a difference.