Final few days before we race little mans car. Any last minute tips or tricks Texags wants to pass along?

Big question should we really worry about the 5.0 oz rule or dont waste the time? Currently at 3 5/8 oz.

what shape is it in? the more like a flat, aerodynamic piece of wood the thing is, the more weight you should put on the front of it.

Is this for Cub Scouts or what?

You really want as close to 5 as you can get. But if its not practical with the car design to add more, then don't fret it.

YES, weight down the front end...get some mineral oil in an eye-dropper and lube the axles near the wheels before racing, and use an exacto knife to make little shallow X's on the outer edge of the wheels to make rudimentary tire treads...Yes I was a cub scout and yes I won the PWD once.

Put the nails that act as an axle into a dremel and use sand paper until they are smooth.

I won the PWD... then I quit scouts, figured I should get out while i was on top

Graphite the wheels.

Great advice everyone.

Here is some info;

Car is mostly wedge shaped. Painted with flames....makes it go faster!!!

I have been told no liquid lube, just graphite.

People also say more weight in the back not the front??? Something about a kick when the car goes from down to straight.

The adults get a chance on Friday night to run the cars and make final adjustments for Saturdays race.

http://cgi.ebay.com/ULTRA-FAST-PINEWOOD-DERBY-CAR-BUILT-by-PHYSICS-TEACHER_W0QQitemZ330207151218QQihZ014QQcategoryZ2595QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

If you are in Dallas--I'm sure someone will have one of these... Prob. Cash's little brother.

Stumpy put graphite on the axles. (if they allow that)

Reduces friction.

Tell the little L good luck for me.

Guess I should read the thread first...

Here's what you're going to do, take that baby out and paint some flames on it, but get a cool decal....maybe like a number 18 on the sides or something.

1. Get as close to the weight limit as possible and try to use a digital scale.

2. grind down the burrs on the inside of the head of the nail that acts as the axle.( allow wheel ample room to move on axle)

3.(if allowed) mount the wheel on a drill and try to smooth it out as much as possible and ever so slightly round the wheel. this will create a smaller surface that is intact with the track.

4. Drill a 1/2 inch hole dow the then length of the car starting from the back. use this hole to put your weight on the car. I used lead shot in mine and plugged it with a cork stopper. i'm not sure if you can use lead shot so you may just have to use the bullet style weights.

5. use graphite on the axles. you can buy round stickers(the kind you use as price tags for a garage sale) and place them on the wheels as hub caps. before you do though, apply graphite to the outside of the rim, and then place the sticker over it. this allows the sticker to act like a patch and keeps graphite on the wheel throught the race.

6. Hope for some good luck.


these things allowed me to win 1st all the way to the council race twice and I took 4th once of those time. However at that time I was going up against lathe turned and beaded wheels which was impossible to compete against.



most importantly, have fun.

Jock if Stumpy's wife has anything to do with it there will be the number 24 painted on it.

From a former state champ:

Ask yourself first....do you want to win? If so, then take the time to work your butt off.

Take a visit to your neighborhood hobby store.

- Friction is not your friend. Get a Dremel. Put each axle in the bit and rotate at high speed. Grind down each axle with one of the Dremel bits held by a plier until you can visually see the valley. No need to overdo it; just a slight indentation will suffice. Make sure that the ground area does not exceed the width of the wheel hub.

- Polish the axles until they shine like chrome with a polishing cloth.

- You don't need to do anything to the wheels. Nothing. Don't get cute and try anything with the inside hub surfaces.

- Weight your car to the rear, approx 60-70% of the car's weight should be over the rear axles. Get some lead plugs and place the weight over the rear 2 wheels evenly.

- Invest in a postal scale. Make sure you are as close to the weight limit as possible w/o going over.

- Only 3 wheels need to touch the surface. Again, friction is not your friend. Choose one of your front two wheels for this, but make sure the difference is as slight as possible. There is no Pine Box rule against a 3-wheeled car, but you don't want to draw obvious attention.

- Aerodynamics. Think wedge shape. Lower your front profile. Think paint. Think high gloss and very shiny and polished.

- Graphite powder for your lubricant. Put it in a plastic zip lock and immerse your axles in it. Shake well.

- Don't use the axle slots that come with the box. Fill them with wood putty. The longer your wheelbase, the faster. You cannot have the wheels extending beyond the front or rear, so just get as close as you can. Find a friend with a good drill press to create the new axle slots.

- Make sure the 3 "real" axles are aligned perpendicular to the car and make SURE they aare precisely parallel to each other. They should be slightly cambered outward (wheels in at the top and out at the bottom) so that they run on a corner of the wheel. Again, it's a friction thing.

- Before gluing the axles to the car, take each axle (hopefully you've ground 8 of them or so) and take turns spinning the wheels on them. Take about 8 wheels and do this. Pick the best spinners and there's your set.

- Glue the axles (w/ wheels mounted) securely.

- On the day of the event, make sure the car never leaves your eyesight. People will accidently "drop" cars or do something to them to prevent you from winning.

- Make as many cars as you can, and enter as many classes as you can.

- Have fun and remember to teach your kid that winning involves hard work and preparation.





[This message has been edited by Picadillo (edited 1/27/2008 1:40p).]

Got a ton of years in scouting, and the bottom line is:

1. Aerodynamics have minimal effect.
2. Weight in back is marginally better (a physics teacher in our pack confirmed that).
3. Reducing wheel friction is the key!!
a) needs to roll STRAIGHT (test off track) recut the axle grooves if necessary
b) no wheel wobble, don't let them touch the body of the car at all
c) cant the axles so the wheels don't touch the track flat, but rather on their outside edge
d) polish metal burrs off nails (axles) and plastic burrs off wheels

However, the best laid plans...we had a scout win whose Dad wasn't around to help and all he did was take the block, paint it yellow and use a black magic marker to make it look like a school bus. But the grooves for the nails were straight and it really ran true.

Good luck.

Edit:Wow...Picadillo's post covers it all. Must have put that in as I was typing.

One other thing...our pack ran an "OPEN" division for the dads (no limits) and actually had specific rules on how much/little dads could do based on the age/rank of their Cub. Once we started doing this, we found that the boys' cars started looking more like it was really their work.

[This message has been edited by kbarj (edited 1/27/2008 1:46p).]

My son's car took first place last week, and here's my tips:

1. Sand and polish the axles. The polish is a white powder that you mix with water. That is, without question, THE most important thing. On race day, add the graphite powder.

2. Location of the weight is IMHO irrelevant, and the best way to do it is dependent on the track anyway (whether or not there is a "hill" after the initial descent or not). Put some in the front and some in the back and you'll do fine.

3. Let the kiddo do as much work as he wants.... cutting, sanding, painting, decorating... it's fun to win, but more fun to win with a car that he made, not that his dad made.

Hahha you guys should have been around to help my dad out.

In around 3rd grade my dad was helping me make the car. We had painted it, glue gunned some **** on it (i think I was trying to win a theme), and with the next day being pinewood derby my dad was beginning to add the weights when I went to bed.

He used a blow torch to melt the lead and wouldn't you know it...something we painted the car with lit on fire. So now...flaming pinewood derby car.

Needless to say he repainted it that night and we were good as new. Still funny though.

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If I ever have kids (God forbid) I will create acceleration vs. terminal velocity plots comparing the performance of increased total weight over the track length.

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your son stands absolutely no chance of ever being cool.


he will, however, win some pinewood derbies.

Weight in the back is to maximize potential energy.

Rodo

I was in the top three places every year. My brother was first in his only year. We always had wedge shaped cars, used graphite on the wheels/axles, and the weight was always in the back. My dad would actually drill a large hole about the size of a quarter in the bottom of the car and would melt lead into the hole. We always went to the event too heavy and would weight in at the event. We brought a drill and just drilled out as much lead as needed to get the car legal. Along the friction is your enemy line, we would always sand down the wheels to make them smooth and actually sand then at an angle so that only the inside of the wheel would make contact with the track.

Re: the car on ebay



What sort of parent would shill out $150 for his kid to win a block of wood race?



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the next attack will probably be in NY...maybe a nuck... -- overwater

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Like racing a matchbox car vs. a ferrari down a hill in neutral. The matchbox car accelerates quicker and wins the race if the course is 20 ft long. But at 1/10 mile the Ferrari wins by a ton.

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Didn't MythBusters have an episode where they tried this?

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Like racing a matchbox car vs. a ferrari down a hill in neutral. The matchbox car accelerates quicker and wins the race if the course is 20 ft long. But at 1/10 mile the Ferrari wins by a ton.

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Hot Wheels cars are one thousand times better.

weight in back = more potential energy...

100% potential : 0% kinetic, at the top...
0% potential : 100% kinetic, at the bottom...

you want to make the transition as efficent as possible.

so what if you could make the weight shift along the car during the course to optimize energy?

If I remember correctly, weight that shifts during the race is outlawed.

Yes, shifting weight will get you DQed, as will sanded wheels.

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as will sanded wheels

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why? sanded wheels are one of the most obvious and easy to do things as far as engineering an efficent car goes...

it's not like everyone can't do that...

shifting weights changes the mechanics of the vechile...

i got 2nd in state one year....and i believe what ended up doing it was actually an accident.....

one of the wheels was off balance...and the car while on the track would shift from 3 wheels touching to 4 wheels touching.....

we didnt have any special design or anything...other than the it looked like a shuttle.....

Altering the wheels is against the rules.

You can sand the wheels, but only slightly. Here's the official rules:

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Old Style BSA wheels are no longer allowed. These wheels are not in the current Official BSA kits and are no longer approved by BSA.

The wheel diameter cannot be reduced past the ridge (rippled) edge and the ridge (rippled) edge must remain intact on the entire wheel.

Wheel treads may not be rounded, tapered, grooved, shaped or positioned at any angle. Wheel treads must run flat against the track surface.

Beveling, tapering, grooving or reducing the tread width of the wheels is strictly prohibited. Wheel bearings, washers or bushings are also prohibited.

Removal of any material from the wheel sidewalls or face is not allowed. The front outside wheel sidewalls & face must remain intact. All Wheels must have the “BSA” “Pinewood Derby” on the sidewall completely intact. Anything else will result in disqualification. Additional items such as wheels bearings, washers, bushings, Wheel and Hub covers are also prohibited.

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We had to DQ two cars last week for altered wheels. Luckily, they were able to attach unaltered wheels in time to race, but they lost the sanding and polishing they had done on the axles.

[This message has been edited by Dr. Teeth (edited 1/27/2008 5:48p).]

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weight in back = more potential energy...

100% potential : 0% kinetic, at the top...
0% potential : 100% kinetic, at the bottom...

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Absolutely true. You want your car to be faster in the stretch. Weight in front will make it quicker out of the gate, but weight in back will make it faster towards the finish.

But like I said Pico, some tracks have a hill on the straightaway... if that's the case, weight in the back will slow it down. So it all depends on your track.

If you don't know... even it out.

can someone sketch me a quick free body diagram?