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PINEWOOD DERBY

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PINEWOOD DERBY

Postby RW TECH » Wed Feb 03, 2010 3:47 pm

Hey guys,

My buddy's helping his kid with a pinewood derby car and weight placement came into question. Apparently it's common to place weight to the rear of the car, but that's not making any sense to me. I'm visualizing a car that wants to be steered around by having weight at the rear, instead of one that wants to "fall" straight with weight near the nose.

Any of you have opinions or experiences to share?

Thanks.
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Re: PINEWOOD DERBY

Postby mbrooks » Wed Feb 03, 2010 6:39 pm

my neighbor did some of this stuff for his girls, and he probably participated more then he should have. he told me there was a lot of stuff on the internet that he researched, like putting the wt. as far back as possible, mounting 4 wheels but only letting 3 of them touch, things like that.

one guy mentioned putting wt. at front and rear, increasing the angular moment, hence the car wanted to go straight, shaping the front with the nose as high as possible so when the arm slid forward and down the car had a head start against a car that had a lower nose.

here is a description of the wt. thing if it makes sense--

Your weight should be very dense and as far back on the car as possible. The further back it is, at a 45 degree angle, equates to lifting the weight higher and therefore the weight has more potential energy. More PE = more speed.

interesting stuff, good luck.
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Re: PINEWOOD DERBY

Postby ZIGGY » Thu Feb 04, 2010 3:27 pm

X2 Brooks. There are actually speed parts available, like "trued" wheels, etc.
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Re: PINEWOOD DERBY

Postby Alan Roehrich » Thu Feb 04, 2010 9:30 pm

The "three wheels on the ground" trick works, provided you can keep it stable. If it wobbles back and forth, on and off that wheel, it will be slower, not faster.

Buy oversized nails/axles, and true them up in a lathe and polish them, watch the burrs under the heads. Get them big enough that once true, they are still oversized, so that you can do the same to the wheels. They sell a mandrel you can use to mount the wheels.

The really fast cars are the ones that have had the most attention paid to the wheels and axles being trued up, polished, and most of all, properly aligned. That makes more difference than the "tricks" and a car that has had that done, but no tricks, will be a trick car without the detail work 9 times out of 10.

We used to have "building days" where we got our scouts in the shop, and taught them to do stuff themselves, with supervision. We showed them how to build cars, and how to make them fast. And we taught them it was work, effort, and attention to detail that makes winners. The only things I did for the scouts were things that were too dangerous for beginners to do. And even then I made them help with all of the set up and details, they did the work right up until the power was turned on.

I did build a couple of my own, the adults would race their own. I had real narrow bodies (think old indy and dirt track roadsters), with dowels to hold the axles out so the track width was legal. I even streamlined the dowels. And I went so far as to drill the entire body out so I could put a round ball in it for ballast. I put a steel ball in for ballast that sat in a shallow recess in the back, and then rolled forward as the car went down the incline on the track. It hit the inside 1/2" back from the nose about the time the car hit the flat. I drilled holes in the wheels to lighten them (I also crowed them in the lathe, they're too wide), then used little "price dots" to streamline them (like Moon hubcaps) and hold dry graphite and moly.

The list of things to do is endless. But I always made the kids decide what to do, and made them do it. We had a lot of fun with it over the years.
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Re: PINEWOOD DERBY

Postby Speedbump » Fri Feb 05, 2010 11:03 am

Correct, the second biggest secret in pinewood racing is wheels and axles. The first is making sure the scout is involved, does the R&D and the work and has fun. My personal experience (and inclination) was that too many parents became over involved and let their super competitive automotive instinct(no one on this forum suffers from that I'm sure) win to the detriment of the child. My son and I did OK but lost to a couple of cars where it was obvious the contestant couldn't have built the car. It's a real shame. The idea of these activities is to HELP raise your kids, not hurt. Sorry about the soap box but it urinates me off!
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Re: PINEWOOD DERBY

Postby RW TECH » Fri Feb 05, 2010 11:16 am

Thanks for all the responses guys.

THE thing I'm stressing to my buddy at work is to have his son's hands in every single thing they do. My friend tells me his kid has a lot of technical apptitude and his skills are apparent. That being said, I'm strongly encouraging my friend to think up as many easy experiments as possible & make sure he completely explains theory behind the experiments to his son plus the expected outcomes.

This same coaching approach was used by myself and a different friend with his son. The success of it is undeniable, considering the fact that his son went on to college & graduated with a high GPA in engineering, then became a Technical Specialist in Advanced Product Creation with General Motors Powertrain. The same kid also won IHRA Top Sportsman Division 5 championship last year.

Since none of us on this end come from any rocket scientist backgrounds & we're all poor (GM kid's dad drives a truck at a steel mill) I want to keep encouraging the pinewood derby friend to handle his son in a similar fashion.

Alan R, I like your rolling ballast idea & thank you plus others for these ideas. Keep 'em rolling in guys! :)
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Re: PINEWOOD DERBY

Postby ASMART » Sun Feb 07, 2010 12:41 am

Good general info here. http://home.simplyweb.net/bosworth/index.html My son and I followed a lot of the advice and he not only beat the kids in his din he beat the entire pack. The weight at the rear is essential. Think about it. WHen the front of the car hits the bottom of the track, gravity stops speeding it up. How ever, the weight at the rear continues pushing after the front has already hit the level part of the track. Our pack limited us to use the BSA kit only and could not modify the wheels. How ever you could do what you wanted with the BSA axles. Putting the axle in a drill and using a file to smooth the portion where the wheel rides and the inside of the axle/nail head is essential. We also polished the axle with sand paper provided in a wheel/polishing kit at the local BSA shop. Good luck, it is a lot of fun. Oh ya, the sight has some pdf files with different paterns you can choose from. Hobby Lobby has a few different weight kits available. We used some of the stick on weights. No drilling required!
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Re: PINEWOOD DERBY

Postby Wannabe » Tue Feb 09, 2010 1:27 pm

The wheels and axles are the primary concern. Take time to make sure the nubs are off the outside of the wheel, and you sand the wheel just slightly so only one point is hitting the track and the jagged edges are off the wheel. The tricks with the axles have already been spoken, but are important.
Check ebay. They have weight/hardness and truness matched factory BSA wheels with some of the stuff already done to them. And depending on how your rules are done, there are other things you can purchase. (Grooved axles, lightened wheels, etc.) Do the wheels, increase the wheelbase if they allow, and make sure the axles are installed straight and alignment is good.
Alot of pinewood derby is just dumb luck anyway. Do all the you can to make it fast, and then watch the black magic take over.
But make sure the kid does all the body design, paint and that type of thing. That is what they want to do anyway. Taking over in this area really just isn't cool. And if you do too much, it will turn out like this;
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Re: PINEWOOD DERBY

Postby Zac28 » Sat Feb 13, 2010 12:56 pm

Man pinewood derby is great. When i was 6 or 7 my dad and i built my first car an on that one he did most of the footwork cus i was just learnin about mechanics. He raced while i was growin up an we have a family owned and ran machine shop so he was tryin to get me thinkin in a mechanical sense at a pretty early age. Well after the first year he did less and less on my cars an i took over more and more, an we were the reighning champs in laplata county for 5 years. It was an excellent father son activity and it jumpstarted my interest in speed( which i think was his main goal) and now i'm 23 and attending the best engine school in the country in my oppinion an trying to take my bshop to the next level. I lost my dad at the beginning of 07 an i'll tell you guys, if you have children that is one of the best things you can do with them. I will always remember that time of year with my dad an those memories are somethin i wouldn't trade for the world. So get to sandin fella's
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