Pinewood Derby Secrets

[OneHour]

So ... what is your secret? There are new cubs, new parents, and newbies who are looking for helps and hints. I'm fairly sure that there pwd gurus among us who would love to shed his/her secret so that everyone can benefit. This will encourage folks to help their sons to make their own pinewood racer instead of buying one on eBay! There are books written, video/dvd made, and knowledge passed from one generation of pinewood racer to another. Now, let's be good sports and not posting something that is out of a purchased book of "how to." It will not be fair to that author. If you know of a trick that would help, I'm sure everyone will be appreciative of the knowledge.

 

Here is a good derby forum: www.derbytalk.com

 

I'm not an expert. I've only been building and help my sons to build pinewood derby cars for 7 years, going from not knowing the minimum weight of 5 oz (and having my oldest tiger's car stopped dead on the track 1/2 way down) to help everyone in the Pack to be very competitive. So.. the followings are what I found to work. My oldest used it and won 3rd overall in our Pack of 110 cars. My second used it and won 1st overall in our Pack of 96 cars. It (as other tips and tricks) is not the only factor. The other factor that everyone seems to forget is LUCK! I'll start:

 

1) Use the full 2 inches (outside wheel to outside wheel) that the Packs rules give you. This will allow the wheels to travel farther before hitting the center guide strip. Remember, every time that the wheels hit the guide strip, the car slows down. So going straight is the key! Axles must be in straight front to back. That is square to the body. True the axles, don't trust the slots! If you have one, use a drill press to ensure all axles are straight. After pressing in the axles, test the car for crooked wheels...roll it on the floor. If the wheels are on straight, the car should roll 8-10 feet in a fairly straight line. Should the car turn left or right, you need to tinker with the axle placement without removing them from the car body, until it rolls straight. After you have finished the body, just press the axles with the wheels in an glue it!

2) Leave a lot of wood in the back to put in the weights. It was determined that the best location for the weight is towards the back of the car. Drill and implant the weight in. Use the bullet fishing weight. Tungsten weight is the costliest, but it will allow you to keep your car profile thin. A car with more weight to the rear generally grabs more speed down the slope. Many suggest having the center of gravity at 1 to 1 1/2 inches in front of the rear wheels. But be careful not to put too much or all of the weight in the rear or your car will pop a wheelie.

3) Use your imagination. Be creative. Shape has the least to do with winning. At this level, aerodynamic has really no bearing; however, having said that, in the past races, it seems that a wedge-type of car does better than other shapes.

4) The axles (the four nails) that come in the kit have several flaws, namely burrs and crimp marks. Remove them marks by chuck the axle into the drill or drill press and polish the axles. First with a 400 grit sandpaper if you have a really bad spot, then 600 grit, and then use 800 grit. Finish off with a chrome/metal polish.

5) Get the weight as close to the 5-ounce limit as possible. The heavier your car, the faster it will go. Remember, gravity is powering this car.

6) Break in the wheels by spinning them with lots of graphite. Lube the wheels and axles by squirt graphite into the wheel hub and spin the wheel. I'd use graphite. The teflon does not work well at all especially in humid area such as Houston. Spin each wheel and count the number of seconds that it spins till it stops. Without any lubrication a typical wheel will spin up to 4 seconds (or a count of 1001, 1002, 1003, 1004) and sounds very coarse and rough. After it is thoroughly lubricated with graphite, the wheel should spin about 15+ seconds and sounds and feels very smooth. The best set of wheels from previous races can spin up to a 25+ count. The more lube the better! If you can get the wheels to spin forever without stopping, patent it, cause you have found the long sought answer to pinewood derby tips and tricks (as well as answer to friction) and can get very rich from it!

 

Helpful websites:

Non-commercial sites:

 

The Ultimate Pinewood Derby Site:

http://members.aol.com/randywoo/pine/

 

The Effect of Weight Placement on a Pinewood Derby Car (Science Fair experiment):

http://members.aol.com/StanDCmr/scfairm.html

 

How to Build Pinewood Derby Cars by eHow:

http://www.ehow.com/how_7445_build-pinewood-derby.html

 

The Physics of the Pinewood Derby:

http://www-cs-students.stanford.edu/~mdevine/pinewood/pinewood_derby.html

 

Pinewood Derby Race Tips by Scoutorama.com:

http://www.scoutorama.com/derby/

 

Ol Buffalo Pine Car Page:

http://www.three-peaks.net/pinecar.htm

 

Shape N Race Derby:

http://www.rahul.net/mcgrew/derby/

Collection of Pinewood Derby Sites:

http://www.geocities.com/~pack215/pinewood.html

 

Pinewood Derby Super Site:

http://home.simplyweb.net/bosworth/

 

Pinewood Derby Car Design by Stan Pope

http://members.aol.com/standcmr/pwdesign.html

 

Commercial Sites: (DONT BE TEMPTED TO TAKE SHORT CUTS!)

 

Pinewood Derby Car Plans and Supplies (Maximum Velocity)

http://www.maximum-velocity.com/

 

Sample Pictures of pinewood cars:

http://www.pinewoodpro.com/pinewood-derby-car-pictures.htm

 

ABC Pinewood Derby

http://www.abc-pinewood-derby.com/

 

Great Decals

http://www2.towerhobbies.com/cgi-bin/WTI0091P?&C=YWE&V=JAH

 

1Hour

[SSScout]

The more Potential energy, the more Kinetic energy...

*Mount your weight as high in the aft end as you dare. Cars with weights in the belly of the car are slower then with weights high in the rear. The fastest car we had one year had a wedge shape with a big bolt glued vertically on the top of the rear (5.00 oz.)

*If the car does a controlled wheelie, so much the better, Less wheels on the track, less drag. That said, you still can't have the aft end drag on the track.

* Listen to the man about axle drag....

 

LET THE BOY DO THE WORK,DAD>>>

[OneHour]

SSScout, pop a wheelie is good ... except when the car lands back onto the track. Nine out of ten times, it will land crookedly and drags all the way down the track. One of my second son's cars did this. He mounted the weight all in the rear! After four heats, his car averaged 2.89 sec (good enough for to be in the top 10), until the fifth heat where his car ran on the lane with a known slight bump. His car popped a wheelie and landed crookedly. It corrected itself and ran on all four, but finished last in that heat with a 4.1 second. His car ended up finishing 31 that year.

 

SSScout points out something that we noticed too. The wedge shape seems to be the best; however, that would make it too monotonous to have 80+ wedges! One year, we had a surfboard that finished 4th overall and a skateboard (w/a dude) that finished 6th. One year, we had a slim wedge that had a donut weight mounted on top right above the rear axle. It finished 1st overall. So ... you can go for looks or you can go for speed!

 

The easiest way to keep dad from interferring is to have an open race! In our pack, we hold an 18-wheeler race in addition to a pinewood open race. It will take all the time that he has to put one of those trucks together! It's great! We race cabs and trailers together and have a separate one for just the cabs, all in single elimination!

[trlarue]

Last year we put the weight as far forward as we could even notching the front of the block. then we jacked up a rear wheel about a 1/16 of an inch, basically just enough for the wheel to clear the track.

Three wheels create less friction than four.

[nldscout]

if all 4 wheels are not touching then car would not be raced according to rules

[OneHour]

Racing on all four may be dependent on the rules of a particular pack. Our pack did not specifically disallow it. I do notice that 3 wheels cars did not finish 1st or 2nd in our pack for the last 3 years. Running on 3 is harder to keep the cars running straight than 4 and that's the key! Running true and straight will prevent the car from careening into the guide rails and ride them all the way down. This is where most of the friction that slows the car down occur.

 

 

[msnowman]

Our Council's rules on wheels touching for the last 3 years has been that all 4 must touch. This wasn't the rule 4 years ago when Nephew had his best Pack Overall Finish (2nd and a chance to go to the District Race). He has enjoyed helping me explain the rules each January to new boys in the Pack by explaining that "This car was legal when it raced but now would get me kicked out". He even does the tippy test to make sure each car has 4 wheels touching so nobody gets dq'd.

 

Its little things like that which prompted our Pack to host a Car Pick Up and Rules Review event each January. The rules do change and often vary from what you find on the internet (since some are Council dependent). We hand out the cars, the rules, explain the rules, give tips and have sample cars from previous years. We even have a short length of the old track to hook the fresh faces on racing. This year we hope to add a seperate PWD workshop for those boys with nobody to help them.

 

YiS

Michelle

[WDL Mom]

I would agree that the wedge shape has done better over the years in our Pack. Weight placement and lubing the wheels is also critical.

 

I however, seem to enjoy the show aspect more than the speed...

 

Last year I entered a Racing Laundry Basket (It was very slow!) Filled it with Barbie clothes... when it hit the finish the clothes flew all over the track! It was great. The boys took great pleasure in beating the Laundry Car!

 

This year I am thinking along the lines of the old Chia pets... remember the pottery that grows??? A chia car.... May have to mow before the race!

[SSScout]

Clarification:

I did not mean to travel the length of the track on only two wheels. What you try to do is put the LEAST weight on the front axle and the MOST weight HIGH and behind the REAR axle. The front wheels are still needed to keep the car centered over the center guide rail.

 

What he said about the axles and spinning wheels.

 

YiS

[KoreaScouter]

Little KS did his 5th grade science project on "What makes a PWD car go fastest?". He got about 30 kits, and configured them differently. There were blocks, wedges, paint, no paint, max weight, weight out of the box, weight in different places, polish, lube, polish/lube, no polish or lube, and so on. The pack left the track up after pack PWD, the school let him have cafeteria access, he made up worksheets, and we spent the entire next day running the test cars (and a control car).

 

Here's what his experiments revealed.

 

1. Shape doesn't matter. Blocks and wedges with all other things being equal showed no statistical difference in speed over multiple runs. Hypothesis: If wedges appear to be faster, it's not the shape, but the fact that a "team" that bothers to shape the car is also polishing axles and lubricating. Not saying that aerodynamics don't matter at all, but the speed and distance of PWD render shape a much less important variable than others, below.

 

2. Weight matters...a lot. The 5-ounce cars and the stock weight cars generally stayed neck and neck down the track, but the stock weight cars had a lot less stored kinetic energy, and slowed markedly after they bottomed out.

 

3. Friction matters, but not as much as weight. Again, all things being equal, polished and lubed cars consistently finished ahead of those not polished and lubed. But, their margin of victory isn't as great as the 5-oz cars demonstrate over the stock weight cars.

 

4. The position of the weight doesn't matter. He moved it all over the place, and there was no statistical difference in the results.

 

In my experience as a Cubmaster (twice), I can offer these PWD secrets. They aren't really secrets, but you'd think they were, because so many parents don't seem to be aware of them. They are:

 

1. Let the boy work on the car -- it's intended to be a shared experience. You shouldn't do it all, and neither should he. Power tools, inhalants, and safety are individual decisions, but even the newest Tiger can pick a design, hold a dremel, put on stickers, and make it his own.

 

2. Let the boy race the car. If your pack has adults handling and putting cars on and off the track, change your methodology. This isn't meant to be a spectator sport for them. If you need stools or platforms, get or make them. Both times I was Cubmaster, our most strictly enforced rule is that "only the boy who built the car will handle it, unless he allows his parent to help him in the pit."

 

3. Overcome the "new guy" disadvantage with car clinics about a month before PWD, with tools, paint, equipment, etc. It'll be good for new families, single moms, families with deployed parents, parents who are all thumbs, etc.

 

In my opinion, the ribbons and trophies don't last, but the memories of building the car with a parent, and racing it with his buddies, last a very long time. Little KS is 16 now, an Eagle Scout, playing football, driving, dating, working part time, and planning for college. Every time we've moved, his PWD cars somehow get packed, unpacked, and end up back on his shelf in his room. He's not sure where the trophies and ribbons are, but he can tell you stories about each car, how and where he built it, who his buds were when he raced it, and how much fun it was.

 

KS