Posted: 3/6/2015 10:41:40 PM EDT
| My six year old joined scouts this year, so we are about to enter our first Pinewood Derby race. We've watched quite a few videos on YouTube, and have been getting our car ready now for the last week or so. We've polished the axles, smoothed the tires, and are working on getting our weight to exactly 5 oz. Haven't decided on whether we want to attempt riding the rail, but will likely be running on 3 wheels. Any other tricks or suggestions you've learned running these races? We have had a lot of fun building the car, and don't expect to win, but would at least like to remain somewhat competitive. Thanks! |
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You want as much of the weight as possible as high as possible, and to the rear as possible without making your car wheelie.
It has to do with the acceleration of gravity. 9.9 meters a second per second... just a slight edge over the other cars with respect to the COG will result in greater acceleration towards the center of the earth, but the track obviously guides the cars on a new path. Friction here is the enemy. Higher Rearward weight distribution makes more speed potential. Decrease the friction in your wheels to actualize that potential. Yes I have won pinewood derby car races. |
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Quoted:
Make sure you paint it sloppily so nobody notices all contact surfaces are covered with graphite. Paint it a gray / silver to match graphite, after polishing nails / axles as has been stated. Also, use lead shot to bring the weight up to the max, as explained in another post.. |
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We took 1st place this year. In addition to what you have done, Here are some tips.
Re drill one of the front axel holes slightly higher than the other side 1/16 of an inch or so. The idea is to have the car only run on 3 wheels. Maximize the use of gravity. Get the weight as far back on the car as possible without popping a wheelie. Dry the wood in the oven to remove any water weight. Then add weight in the back. I shoot for a balance point of about an inch in front of rear axel. Don't bother with the rest of this if you don't first maximum the use of gravity. When the car is finished. Use a piece of string to hold it on a treadmill. At low speed check alignment. if car pulls left or right use a pair of pliers to rotate front axel nail, the one that its running on, in small increments until car runs straight. Now check the back wheels to see if they are hitting car. You want them to rub against the nail head not the car body. And you don't want wobble. Use pliers to rotate and maybe even camber the axels to fix any issues. |
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In addtion to smooth wheels, polished axels and running on 3 wheels.
Bake the block in the oven, 200-250 degrees for a couple of hours to remove weight from moisture. Pick a design that removes wood / weight from the front half of the car and has a wedge / thin shape. Then put all the weight you can in the rear of the car, center of gravity should be just in front of the back wheels, this creates the most inertia. Use tungeston screw in weights in the rear of the car. Drill the wheel holes with jig for derby cars so they will be as straight as possible. Put the rear wheels as far back and the front wheels as far forward as possible. Longer wheel base increases speed. Google: Pinewood Derby Ultimate Secrets My son and I loved making these cars. Once we figured it out we won 3 years in a row. Good Luck! |
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ha, when I was a kid I won just about every year from age 5 to age 12. most of the time I placed the weights under the car with the wedge pointing backwards (most of the weight just behind the front axle. scuffed the wheels a little with sand paper and put some graphite on the axle.
I think the key really was that I left the axles and wheels in the box until the night before the race, or if I built it early it went on a shelf and I didnt play with it. looking back the benefit from keeping the axles clean and not bending them was probably better than any amount of weight distribution/design. |
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Good suggestions already.
We took 1st place in 3 different classes years ago. Cut your wheels. Put them in a drill, use a very sharp chisel at a 90 degree angle to the face of the wheel and leave a very thin small portion for it to ride on. Essentially removing about 70-80% of the tread face. Then spin tires in the drill onto a cloth heavily coated in graphite powder to "impregnate the wheels". Make sure your axles are mirror polished. They also sell lathed axles that have some removed to reduce friction. Those help tremendously. Rub graphite into the wood where wheels hit he body. Do not paint that area. The paint will be "sticky" no matter how long it dries. Oh and then let your son build his own car.... We always had an adult class for that reason. |
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Quoted:
ha, when I was a kid I won just about every year from age 5 to age 12. most of the time I placed the weights under the car with the wedge pointing backwards (most of the weight just behind the front axle. scuffed the wheels a little with sand paper and put some graphite on the axle. I think the key really was that I left the axles and wheels in the box until the night before the race, or if I built it early it went on a shelf and I didnt play with it. looking back the benefit from keeping the axles clean and not bending them was probably better than any amount of weight distribution/design. We drilled holes in the bottom and filled the holes with melted lead from fishing weights. We also put graphite on the axles. The car did well pointed either forwards or backwards but as I mentioned earlier not so well when it was half off the track. I was only in the cubscouts for one year I think. Still have that car someplace I think. |
| Absolutely have it running straight on 3 wheels if it is pulling off of center, pull the axle out and use a bit of wax paper in the hole to shim it to straight . Taper the inner heads of the axles to remove friction, or at least remove the casting marks under there. |
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Built a couple of 1st place cars about 10 years ago with my son. The biggest factor in these cars are the wheels,axles and having a 5oz car with the center of balance about an inch ahead of the rear axle.
I was recruited to help my nephew with his car this year because my brother inlaws build last year didnt finish. I guided my nephew in cutting it out then I left him some files and sand paper to work on it. Weights to go into car. 
Weights in car 
I spent about an hour per wheel/axle cleaning them up. 
The chocolate bar in the last pic is a PWD car I was build for my niece to play with. |
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Let your son 100% design it with no outside input at all. Just guide him.
THEN do one from others tips. For some its all about winning to the point there the kid was involved maybe 5% of it. Let the kids do it, teaches self sufficiency and many times, how to handle loss. |