I got a week to build a boyscout pinewood derby car and am looking for any tips you might have, I am a greenhorn at this.

Thanks.

LK

I have had luck thinking out of the box. I don't try to win speed, my son and I go most original. The competition was tough this year so we didn't win but last year we did a yellow double decker bus and won the district.

Remember that 7" long, 2 3/4" wide and 5 ounces. Check with your den but in ours there is no height limitation.

My son wants to do a Chevelle Convertible next year as his final car and go into the best looking category. Has anybody ever done one?

Are you entering the adult derby? Where in Michigan are you?

Oh boy, I've been waiting for someone to ask for YEARS! :disco:

We have 1 last place trophy. that was the 1st time I tried to give guidance.

5 years separated boy 1 from boy 2 and 3.

results with boys 2 and 3:

7 1st place trophies
4 1st and 2nd place wins (both boys entered)

I made the boys do ALL the work, except for spray painting, themselves.

Every time, each of the cars were scrutinized for rule infraction that would make NASCAR look like amateur inspectors. Zero issues were found.

FYI-Where I found the most disappointment and a rapid falling off "kid interest" and very high likelihood of injury was in shaping the body.

Plus what you can and can't do is based on the rules established by the pack. A pack may take the standard cub Scout rules or they have the OPTION to modify them.

So...

Rule #1 - What EXACTLY are the local Pack rules.

You can't make a winner if your car is disqualified for build rules. If you don't have the rules, GET THEM.

When you have them, post them here, word for word.

Then the fun begins. :D

your son is supposed to build it. when i was a scout, i had luck with getting the car down to as skinny of a tube as possible (think jet car), graphite the axles, and then drill threw the center, and fill with lead, get the body just over weight, get to the race, weigh in, drill till it hits limit, and race. i always overfilled a tad, just in case my scale or thiers was off a tad. never won one, but was always in the semi or finals...

your son is supposed to build it.

That's important. That's what it's all about. Guiding them, showing them how to do it, keeping them safe is your job.

your son is supposed to build it. when i was a scout, i had luck with getting the car down to as skinny of a tube as possible (think jet car), graphite the axles, and then drill threw the center, and fill with lead, get the body just over weight, get to the race, weigh in, drill till it hits limit, and race. i always overfilled a tad, just in case my scale or thiers was off a tad. never won one, but was always in the semi or finals...

Narrow (sand) the wheels (contact with track)......less (drag) rolling resistance, however, there is a minimum I believe.

I've always seen and heard that the Father really builds the car for the kid. :rolleyes:

The whole who builds the car is a widely debated and highly philosophical question. Unfortunately most boys these days lack the patience to produce much. Their imagination tends to far outstrip their abilities. So better memories may result from a bit more adult assistance ;-)

The balance we struck in my family is it their idea and they have to be present during construction. BSA really does not want Cub's using power tools anyways, so they can watch (and hopefully absorb some learning) while "dad" creates saw dust.

As mentioned, starting with the rules is ALWAYS a good beginning. I still remember as a kid arriving at the derby only to discover that wheel track was a critical dimension and we had changed that on my car. Mad scramble to fix things ensued.

As a Cubmaster or Derbymaster I always like to ask the boys who wants to have the fastest car. Of course ALL the hands go up :D. Then I point out that only ONE car/boy can be the fastest. A dawning occurs as that message is processed. Then I point out that there are other ways to win a PWD besides fastest car. You can have the best finish, the most creative car, the most un-car, ... and when all is said and done you REALLY win by doing your best. This little minute really helps avoid frustrations and arguments and helps everybody keep perspective and have a good time.

One of our creations one year was a Kirby, the little pink puff ball cartoon character that sucks in everything while riding on jet powered surf boards. My son had to find a decent picture on the internet to show dad what he was envisioning. We made Kirby using a ping pong ball and Model Magic clay (that clay is great: easy to form, dries hard, weighs littls, and paintable -- the Derbymaster gives it :thumbsup: :thumbsup:).

The BSA supply division sells a couple of books that I really like about PWD. The reason I really like them is they define 3 levels of car so you and the boy can decide just how much work and preparation you want to go to. Great life lesson there :thumbsup:

Teach you son about the physics behind the derby as a way to optimize the car. This comes down to really two rules: get as much energy as you can and then keep as much energy as you can. You get energy by having your weight higher off the floor. You keep it by reducing friction. Really very simple :D

So the weight needs to go as rearward on the car as possible and still keep the front wheels from bouncing up and off the track (means have axles towards rear too). The wheels need to spin freely (polish axles, cone the nail head, cone the wheel hub, bevel the outer edge of the axle hole, lube with graphite). Then there is the friction that most miss: the rubbing of the car on the center guide strip. Make the car run straight and smooth the inside edge of the wheels.

The last PWD car I did was a full-fendered El Camino.

Here's my cars from a few years ago...yes some adult "guidance" was provided....

http://i3.photobucket.com/albums/y98/trapperj06/Pderb001.jpg
http://i3.photobucket.com/albums/y98/trapperj06/Pderb002.jpg

I never was any good at making those things fast no matter what we did but we did get a LOT of best of show awards from all the cars we did with the 2 boys.. Here's our car from last year (my sons final car) I figured we'd go all out..


http://img85.imageshack.us/img85/8504/p1180570sf0.jpg (http://imageshack.us)
http://img245.imageshack.us/img245/5257/p1180571la2.jpg (http://imageshack.us)
http://img85.imageshack.us/img85/1892/p1180573fg4.jpg (http://imageshack.us)
http://img85.imageshack.us/img85/7325/p1180569jm3.jpg (http://imageshack.us)[/

your son is supposed to build it. when i was a scout, i had luck with getting the car down to as skinny of a tube as possible (think jet car), graphite the axles, and then drill threw the center, and fill with lead, get the body just over weight, get to the race, weigh in, drill till it hits limit, and race. i always overfilled a tad, just in case my scale or thiers was off a tad. never won one, but was always in the semi or finals...

Exact setup here. Thin down the car as much as possibe. Also sand burrs from the axles. Powdered graphite on the axles. Also watch for rough spots on the tires. We one quite a few in the past. Make sure anything you add to car is attached securely because when I was in it if something fell off the car was disqualified.

My 11 year old son is building one this year the meet is next weekend. So far his car has: Grooved polished axles, graphite lube, beveled wheels, weighted to the rear, three wheels down and a good alignment. All he's lacking is paint.

I have had two boys go through the pinewood derby years. The most important thing I have found is to polish the axles until they are like a mirror......then polish some more.

My boys would think up whatever design they wanted, sketch it on the car, then I would help them cut it out. They took over from there. They would polish the axles with guidance from me, through a multiple step process starting with chucking up each axle in a drill, using a file to knock off the nail burrs, then use several grits of sandpaper. The last step was to use 600 git wet/dry paper then polishing compound, then a final polish with jewlers rouge and wax.

My experience was the shape of the car was not near as important as axle preperation. One year my son wanted to build a brick of cheese. No aerodynamics at all, still won the whole thing.

The boys combined had four first place trophies and three seconds. My older son entered the open class for siblings after he was too old for the pack and won the open three years running.

I entered the open myself the last three years and won best of show all three year. The pictures of my cars are posted on my profile but I don't know how to make a link here.

Most important is to allow the kids to do as much as they want and can. When I was a cub, my dad would build the car and hand it to me the night before the race. I promised myself when my sons wanted to do cub scouts, I would not take the fun from them.

Geez, we didn't have all these categories when I was in Cub Scouts. You were either fast or you went home. I think I lost to a kid who nailed the wheels on a block of wood. I'm not even sure he painted it. :)

My 10 yr old is a huge Corvette fan. I was surprised when he showed me a picture online of the pickup he wanted to build for his pinewood entry.

I drew it the best I could, he rough cut it out of the block, then I did most of the dremel work before he painted it.

http://i161.photobucket.com/albums/t227/66buickspecial/pinewoodcar5-08.jpg

He actually won a couple of heat races before being eliminated. He said he really didn't care about that, he just wanted "Best Appearing".

He was grinning ear to ear when they announced his name for that trophy.:D

http://i161.photobucket.com/albums/t227/66buickspecial/pinewoodcar5-080105.jpg

That is what it's all about.

He's got big plans for this year already. I told him I wanted him to be even more "hands on" and would oversee his Dremel work, but it was going to be all him this year.:yes:

My kid helped a lot with his and it is a great father son project as well as a good lesson on how to win and lose. The car that won 1st this year was obviously done by an adult and hopefully that will reflect in the district. The car was a swiss army knife with perfectly crafted blades that opened and closed.

Geez, we didn't have all these categories when I was in Cub Scouts. You were either fast or you went home. I think I lost to a kid who nailed the wheels on a block of wood. I'm not even sure he painted it. :)

Thats how it was when I was in Club scouts also. They didnt have any rules accept the graphite rule. Even then I had a friend of ours that always took 1st place every year for maybe 3 years in a row. I didnt think about it then but when I think back on it, I would have like to have seen his car inspected to make sure it really was graphite on his axles, as he turned out to be a not so honest friend going into HS.

I think that's what's wrong with the Pinewood derby nowadays. When I was a cub scout I made my car with no help AT ALL. My father wanted to help but I had no desire to let him. I figured if I accepted help it really wasn't my win.
I have alot of friends with kids in the cub scouts and it makes me sick to see how they all put tons of money into their kids' cars and basically build them for them.
My car when I was a kid looked like crap but won the state championship. I've still got that car and the trophy today and I can't stop laughing because i've brought it to the test-n-tune track night and it still kicks all the new cars' asses. They can't stand that they get beat by a thirty-something year old car completely built by a kid. But I love it because I know 99% of them were built by the dads.
I guess the moral of the story is to stop living vicariously through your kids and let them do the whole project. You don't need power tools to build the car. Win or lose, it doesn't matter. Their character is more important.

Greenhorn here. My son just started as a Tiger.

Question for you more experienced....

Has anyone actually run with one of the front wheels "tilted up" so that only 3 wheels (less friction) are on the track? I saw this suggestion, but my pre test runs showed the car wanted to drift and hit the divider, which means it will slow down. Anyone have better results?

-stu

...Has anyone actually run with one of the front wheels "tilted up" so that only 3 wheels (less friction) are on the track? I saw this suggestion, but my pre test runs showed the car wanted to drift and hit the divider, which means it will slow down. Anyone have better results?
Not intentionally ;)

This is one of those things that happens all too easily with no real intent.

Part of making them roll straight is getting the axles straight. I always drill pilot holes for the axles on a drill press before doing anything else. I do this not just for my kid's car but any kid that wants to come to the building workshop.

One year my daughter decided to make a fork lift as the derby was shortly after Girl Scout cookie sales. We tried every trick we could to make that thing go. One trick was to make each wheel roll straight individually by sanding/polishing the wheel tread. If the wheel rolls in an arc it means the outside tread edge is larger in diameter than the inside tread edge.

We also used wax paper shims on the axles to fine tune them as well.

Still was not a particularily fast "car" but it did get LOTS of looks with the digital images of Thin Mints on the pallet on the front :thumbsup:

Greenhorn here. My son just started as a Tiger.

Question for you more experienced....

Has anyone actually run with one of the front wheels "tilted up" so that only 3 wheels (less friction) are on the track? I saw this suggestion, but my pre test runs showed the car wanted to drift and hit the divider, which means it will slow down. Anyone have better results?

-stu

Yes, a 2 wheel car works best. ;)

Not intentionally ;)

Same here. Glue in the axle groove hadn't dried completely. The "helpers" (scouts) were kind of man-handling the cars at the finish line, dropped them quite regularly.

That threw out the alignment on a lot of cars, who were quickly eliminated. (They bounced back and forth on the center guide, slowing them down a lot.)

Absolute dumb luck that the damage to our car was knocking one front wheel up above the track, giving it an advantage. I didn't know that had happened until the races were over, and frankly was scratching my head about how it suddenly got faster.

Didn't win overall that year but wound up in the top 5

Not only drill the axle holes, but do some dry runs on a smooth hard surface, especially if you are drilling by hand. The axles are relatively soft, so you can bent them ever so slightly to correct toe in/out to make the car run straight.

Ok, here's all my tips.

Part #1

You'll need:
Pinewood kit
Drill and bits [also recommend a 3/8" wood bore (flat type)]
Files
Sandpaper (inc. some very fine grits)
Rubbing and Polishing compound
DRY Graphite lube
Small diameter machine screw and nuts to make a wheel arbor. (must fit inside the axle hole. Second best thing is one of the axles pushed through the wheel and jammed tightly against the drill chuck and taped to chuck)
3/8 diameter Pinewood Derby weight.
Bondo, wood putty, or drywall compound
Accurate scale (Post office/UPS store/etc are free)
Lead free solder (large diameter)
Hot glue gun
And what ever else you need to finish the car (paint, etc)

Rule #1 is HAVE FUN (and NEVER let your child use a power saw/cutter of ANY type). ALL of the Scout sites emphasis this and WANT you do do that part).

Rule #2-Rules is rules-Don't teach your kid to cheat.

As in any competitive event, there are rules. Each race may have slightly different rules. It is important to read the rules thoroughly and abide by them. Typical rules include what you can do to the wheels, maximum car length, width and height. Failure to follow the rules could result in your car requiring last minute adjustments before the race or even being disqualified.

Size up the competition and adherence to rules. If this is your 1st year doing this, you may wind up following the rules and losing in the 1st round because almost everyone else is cheating...oh let's be a bit nicer...they INTERPRETED the rules DIFFERENTLY and no one really cared. That's what happened to me. That's your call not mine.

A lot of Packs have a dry-run a week before the race. If yours does and you can make it, go.

Don't worry how perfect it looks unless you have a ton of time on your hands or your child has the abilities of a master woodworker. If time is REALLY tight, show them a few pictures of Rat Rods.

Quick tip on the body. If the rules don't say you MUST use the wood in the kit, go a hobby shop that carries Pinewood supplies and buy a pre-cut body. They were about $5 when I was doing it.

Now on to the speed tips-

Tip-don't put more effort into the body than necessary if time is tight. I'd rather have the fastest unpainted block of wood then the slowest paint job.

Aerodynamics-Don't worry about it. You're not going fast enough to leverage it or be defeated by it.

Gravity and Inertia-If you drop something from track height gravity pulls it straight down speeding up all the way. In the case of Pinewood derby cars, the exact same thing happens, but the track guides it's process.

Pinewood derby tracks generally have a single "ramp" which levels out near the end of the track. This is how you leverage that.

Principal #1-Gravity-When the car is on the ramp part, it is being propelled by gravity. When an axle of the car descends PAST the ramp and onto a flat, it is being driven by inertia. (friction issues later). So when the front axle is on the flat, the rear wheels are still being driven by gravity. The longer the rear wheels are driven by gravity, the faster it will be.

Action-Lengthen the wheelbase. If the rules DO NOT state that the axle grooves MUST be used, the Pinewood rules state that the wheels MAY NOT extend past the ends of the body.

Principle #2-Inertia. Imagine a 100 lb kid and a 40 lb kid headed for the playground slide. The 40 lb kid goes first and is overcome by friction, coming to a stop, near the end of the slide. Now before they can get off the 100 lb kid slides into them. What happens?

Right, the inertia of the 100 lb kid drives the 40 lb kid right off the slide and continues as if nothing happened.

Wood doesn't weigh very much, but if you are going to modify the body, it would be to take weight off of the front and add it in the rear. I used 3/8" pinewood derby weights in holes drilled vertically over or just in front of the rear axle. DO NOT put weight behind the rear axle. This will cause the front axle to "wheelie" and you will lose.

Note regarding weight-The car can have a maximum weight of 5 oz. You want to be at EXACTLY 5 oz. If you can afford to buy a cheap digital postage scale at the office store, do it. If you can't call your friends and see if he have a dighital poatage or kitchen scale you can borrow.

Another free way to measure that is to do all of the speed trick work in advance, including the drilling for and cutting the weights to fit, then taking all of the parts over to the UPS store and getting it weighed.

Bring some solder and a pair of snips with you. If you are under 5 oz, keep adding an inch or two of cut solder until you hit 5 oz. This will give you a pretty good idea of how much more you can add.

I'm sending this now and will start part 2.

there's more than one kind of powdered graphite. get the most finely ground stuff you can find. the stuff I've got is so fine it floats in the air. careful about modifying the wheels, strict rules here. I cambered the wheels slightly so they run on the inside edge which is carefully polished. Ours run on 3 wheels. the wheel not on the track creates no friction and has no rotational inertia. :)

I have a drill press so I used it to burnish graphite into the inside of the axle hole in the wheel. chuck the axle into the drill, run it at the highest speed, feed graphite into the hole in the wheel while working it around.

If I had a lathe I would have turned material off the ID of the wheels, rotational inertia again.

If you want to compete you're going to run into other Dads/kids who are dead serious.

Careful attention to the rules helps. One year I got the wood blocks mixed up between BSA and AWANAs. The AWANA cars have a shorter wheelbase, not legal for BSA. Our local Pack rules and inspection were lax and I didn't find out about the deal till we were checking in at the District meet. It's about the most disappointed I've ever seen my son. Dang.

Part 2

Overcoming friction

The only places that apply friction to the car are the wheels and axles.

Axle speed tricks- As mentioned, the minimum is to polish the axles with fine sandpaper and compound (use the drill).

The axles are stamped out, so there are burrs to contend with. Get rid of them too.

Next trick is to put a wide groove in the axle in the area that the wheel rides. By doing that you can eliminate 50% to 70% of the friction drag between the wheel and the axle.

It does not have to be deep, but make it as wide as possible so that the wheel will still ride on the same axle plane, just as little of it as possible. This will also hold a powdered graphite surplus. That's important because once the car is accepted into competition, you cannot touch it until the race has completed.

Last axle trick, most people miss. If you de-burr the axle, the "nail head" end of the axle will be flat. While held in a hand drill, "machine" it with a hand file so that it is slight "cone" shaped away from the axle. This will remove a significant amount of friction as only a very tiny part of the wheel will come in contact with the "head" end.

When done, polish the axle with very fine sandpaper and then polish it to a high gloss with the compounds. Again, having it chucked in a drill will speed this up big time.

Wheels

IF YOU ARE GOING TO MODIFY THE WHEEL, DO THIS PART FIRST.
The wheels are not round and they have casting burrs on them. If you can get a small machine screw that will fit through the axle, lock it place with a matched nut and the place the whole assembly in your drill. The hobby stores sell an arbor specifically for this purpose.

if you can't find a screw that will fit through the axle, use an unmodified axle inserted through the wheel. Take both and place it in the drill chuck with a snug fit. Keep pressure on the axle head and wheel as you tighten the chuck. When done, use some tape to tape the exposed axle part of the wheel (the inside area) to the drill chuck.

IMPORTANT-You need to keep the wheel from spinning on the axle or you will MELT the wheel from friction.

Once the wheel is rigged, hold the drill flat and use sandpaper wrapped around a flat inflexible (wood) support to "machine" the high spots off of the wheel. I found that a medium grade paper worked best to begin with, followed by something like a 600 grit. When done, polish the wheel surface with compound.

DO NOT DO THIS NEXT PART FIRST.

We have eliminated the outward wheel end friction with the above axle modification. Now we do the inside, the part that pushes up against the body.

Just as we angled the axle head, angle the body end of the wheel away from where it touches to body. Again, like the "nail head" end of the axle, it is FLAT.

I found that without a lathe, the only practical way to do this was by hand using some very coarse sandpaper.

The end result you are looking for is to round the end of the wheel so that only the area around the axle touches the body, not the whole surface.

Last wheel modification is a tricky one, enlarging the diameter of the axle hole in the wheel.

With an unmodified wheel, the entire inside surface of the wheel comes in contact with the axle. by enlarging it very slightly you reduce the contact area between the axle and wheel to a pinpoint size.

WARNING-if you enlarge it too much, your wheels will wobble creating 3x the friction of one not enlarged. If you try it and you mess up, get the smallest diameter screw you can to screw into the axle hole and get a few threads screwed in. This will cause the screw to cut into the wheel and create raised areas. It's a trial and fit effort, but it's a "it's 8 PM on Sunday, and I just ruined the whole thing" solution.

Something I tried that worked very well, was finding a machine screw that was a hair larger than the enlarged hole. I screwed it in about an 1/8" from BOTH sides, NOT ALL THE WAY THROUGH. This caused only the raised ridges made by the screw to contact the axle and screwing from both ends counteracted the threads from driving the wheel inwards or outwards.

Now back to axle placement. Another reason you want to extend the axles as far forward as possible is to trigger the finish line photo cell sooner.

Remember the old top fuelers that had that extra tab at the front axle? It would allow them to stage deeper(is that the correct term for father forward?), because the front wheels would still block the start line beam and the tab would trigger the finish beam AHEAD of the front wheel.

If you move your front wheels as far forward as possible, another faster car could lose by 1/4".

Front end of car design- Usually another missed opportunity.

There is no photo cell at the top of the track, only at the bottom. The cars are held in place by a wooden dowel. The faster your car breaks free from that hold the sooner it starts going down hill.

The trick is to keep the from of the car flat and move the "bumper height" up. By angling the center section away (towards the back) from the "high bumper" front your car will break free faster.

Once you have made all of the wheel and axle mods, test it by holding the axle and spinning the wheel. Try it level and then try it on an angle so that the wheel is rubbing on the nail head. There should be no significant wobble and there should not be a large difference in the time it spins when resting on the nail head. if there is, now is the time to modify.

Keep all your wheel on the track. As others have mentioned, that 3 wheel trick can cause havoc.

Something that I did that worked well was to drill the axle holes and not rely on the grooves. No "dropsies" alignment issues.

Here is a necessary tip. After assembling the whole car, place it on a flat surface and make sure that ALL wheels are in contact with the surface.

Before testing for running straight, here is another tested and proven trick. Bend the axles, EVER SO SLIGHTLY, to cause the top of the wheels to tilt in. Observe the wheel to running surface clearance. There are two advantages to this. One is that the wheels will tend to ride towards the nail head that produces less friction than if the wheel rubs against the car body. The other reason is that only the edge of the wheel is riding on the track, thereby reducing friction as the wheel rolls down the track. Note that this is a delicate operation and may take some time

I ONLY did the back wheels this way.

Tuning

Your car will lose if its steering into the center guide.

Take the time to test it's steering. Start by placing a ruler against the body and measuring the distance from the front and rear of each wheel. They need to be the same. If a wheel is angled, it will steer itself. Once that is pretty much set, test it on a long flat surface.

You want it to be able to roll a good 10 feet. If it steers left or right, make small adjustments until it will cover the distance correctly.

Running it in-

Add dry graphite lube to the axles. Then my hand or mechanical means, spin the wheels for extended periods of time. This MUST be done at low enough speeds to NOT melt the wheels. All you are trying to do is run in the wheels/axles to eliminate any high spots that were left.

Getting to exactly 5 oz or thats what the solder is for.

I used to get the weight of the cars, fully assembled and painted to 4.9 or so oz. We would then take 2-2" to 3" long pieces of solder and bend them into side-pipes. I would always have them drill a small hole to insert and secure the solder, using hot gluing in the hole and along the bottom to hold them on. We would purposely get the cars slight heavier than 5 oz. during weigh in, the boys each has nippers. If the scale said we were heavy, they'd snip a bit of the solder off to make it right.

They would then re graphite the axles, the inside outer edge of the wheels and turn it in.

Good luck to you all!
I'll check back later for questions or PM me. :thumbsup:

Ah yes, that time of year again. As a former Cubmaster and Eagle Scout, let me give you my 2 cents;

1) Follow the District, BSA, and Pack rules to the letter. If your kid DQ's because of "cheats" well, that's your fault, not theirs. How happy will they be when they can't run their car or have to tear it apart to fix something?
2) Allow the kids to build them. Will they be beautiful? Possibly. Will they win? Possibly. Will they have more fun with Dad or Grandpa in the garage teaching them how to build things? You betcha.
3) If your Pack doesn't do a "Dad" or "Leader" only division, DO IT. It keeps the uber-nutso stuff out of the kids' cars. That's what we did, and it works like a charm.
4) Teach the kids & Dads about participation, sportsmanship and let the kids build them!

I prefer F1 cars as they are very angular and easy for the kids to cut and shape. Chris had zero problems figuring that out once I showed him how to use the saws. He only won it all 1 year, and he did 95% of the work. I helped with the chop saw and showed him how to mask it off for what he wanted to do.

My cars as a kid - yes, I was a big-time model builder, so I probably had something on the kids of today. And yes, I did build 95% of these myself.

http://www.rmsresins.com/photos/pinewood/mycars.jpg

Chris' cars:
http://www.rmsresins.com/photos/pinewood/crcars.jpg

http://www.rmsresins.com/photos/pinewood/crwin.jpg

My cars for the Dad's division - the F1 lost, the Chevelle won it all:

http://www.rmsresins.com/photos/pinewood/mika1.jpg

http://www.rmsresins.com/photos/pinewood/mychvl1.jpg

Dad's division, what an excellent idea. Passing that along to the current cubmaster.

Here are the Official BSA rules:

Pinewood Derby Car Dimensions:
* The overall length of the car shall not exceed 7 inches.
* The overall width of the car shall not exceed 2 3/4 inches.
* The car must have 1 3/4” clearance between the wheels.
* The car must have 3/8” clearance underneath the body so it does not rub on the track.

Derby Car Weight
* The car weight shall not exceed 5.0 ounces.
* The official race scale that is used at car check-in shall be considered final.

Wood, Wheels and Axles
* The official pine wood block must be used. The block may be shaped in any way that is desired.
* Official BSA wheels must be used. The wheels may not be cut, drilled, beveled or rounded. You may remove the seams and imperfections from the wheels.
* The axles may be altered, polished and lubricated.

Car Modifications Not Allowed
* Wheel bearings, washers or bushings are prohibited
* The car must not ride on any type of springs
* No starting devices. The car must be freewheeling.
* No loose material of any kind, such as lead shot, may be used.

If these are the rules, there's a lot of modifications that have been posted that could be used, and some that could not be used at all.

Example:
Dimensions-Nothing there that says you can't alter the wheelbase
Weight-Shall not exceed 5.0 oz. Nothing about 5.09. Keep it overweight and trim the extra at the track based on the scale there.
Wheels-You may remove the seams and imperfections from the wheels. Webster's definition of imperfection-: the quality or state of being imperfect. Also see imperfect. Webster's definition of imperfect-: not perfect. So remove the imperfections.
Axels- You modify the axels, inc. their angles. Reduce the diameter of the axles if you can't drill the wheels.
That wax paper idea is a bushing, thus not allowed.

Question re. car mods not allowed for BSA:

* Wheel bearings, washers or bushings are prohibited

--> Does this mean no washers on the axle to prevent inner wheel from rubbing against body?

Another question:

I heard (from another "Dad") that the "competitive" standard BSA class cars have wheels on axles that can spin at least 20 seconds. Is that what your seeing/experiencing?

-stu

Back in the '70s I made a WWII type tank. Was fast since the cannon and turret were higher than everyone else and it leaned a little forward (more a cutting error than on purpose).

They also had a parent's group since the dads all asked for it. Very cool designs, and I think it helped keep them from doing too much help on the kids' cars. My dad made a station wagon cop car. He had a flashing light and a 9V battery hidden inside. The rest of the car was pretty much paper thin due to the battery weight.

Question re. car mods not allowed for BSA:

* Wheel bearings, washers or bushings are prohibited

--> Does this mean no washers on the axle to prevent inner wheel from rubbing against body?



Another question:

I heard (from another "Dad") that the "competitive" standard BSA class cars have wheels on axles that can spin at least 20 seconds. Is that what your seeing/experiencing?



-stu

Correct NO washers

Just happened to be doing some straightening up a few weeks back and came across the box with the last 2 cars we built in it. As i was able to put my hands on them very quickly, I just did a simple test without adding any lube. Mind you they've been sitting for a good 7 or 8 years, but I averaged around 14 or 15 seconds per wheel.

I am currently averaging 13 to 15 seconds; if those guys are running 20 seconds/wheel/axle, then those guys are spending an unbelievable amount of time prepping those wheels/axles. I must have spent 5 hours prepping 4 wheel/axles already...sheeze; of course I am a greenhorn so go figure....I don't know what I am doing.

Gotta be honest to tell you if yours are spinning 14 secs or so, you got a winner there.

Forget about trying to make them better.

Spend the time of all of the other little things, cause it's not 1 thing, it's ALL the things that add up. :D

I just got home from our annual Pinewood Derby this morning. Out of about 50 cars, my son came in 4th. Mind you, he did all the work himself this year (he is a Webelo 2) based on tips I gave him. He won 1st place 2 years ago when dad did most of the work. So, we have some proven methods to back up what I'm sharing.

Make sure the wheels are true round (get an arbor to turn the wheels slightly). BUT...The real key is the axles. Debur and ease the head of the nail AWAY from the wheel. Then polish the HELL out of the axle! We take ours down to 2,000 grit sandpaper, then hit it with pumice, then car paint polish, then the secret weapon - some Minwax paste wax polished to a nice luster. Then use the pinewood plastic "guage" http://www.abc-pinewood-derby.com/wheel-alignment.htm that shows you if the wheels are straight and use the small end to make sure the wheels are the appropriate distance from the car body. We then use graphite to lube the wheels (our pack leaders put this on at check-in on all cars) Also get your added weight centered in the car. Doing this will get you at the front of the "pack" so to speak! :D Good luck and best of all, HAVE FUN!!!!

Here's a picture of our track this morning before everyone showed up. The track is the length of the entire basketball court. Note the video camera hanging above the track. This is a motorized camera that we had follow the cars and the image was displayed on the white wall behind the track (our own version of the jumbotron!). That is my son walking behind the track.

http://www.chevelles.com/showroom/data/500/medium/Scouts_2009_053_Large_.jpg

Good tip on that alignment tool. Forgot all about it but used it for several years. :thumbsup:

Thanks for all the tips, I am going to spend most of the time on the axles & the weight.

LK

like alot of you guys when i was a kid i built my car completely by myself. my dad weighed it for me and added some ball bearings to get it right but i built the thing myself with no supervision or guidance . ofcourse i was building things since i could walk. i think the kid should build his own car and the only help he should get is advice. if he isnt interested enough to do it himself then he shouldnt enter.

like alot of you guys when i was a kid i built my car completely by myself. my dad weighed it for me and added some ball bearings to get it right but i built the thing myself with no supervision or guidance . ofcourse i was building things since i could walk. i think the kid should build his own car and the only help he should get is advice. if he isnt interested enough to do it himself then he shouldnt enter.

Save your breath. I won't change any of the, "my kid is incapable of building the car so I want to do it for them" crowd.
Reading most of these posts, it just reinforces what I said about the dads doing most of the work and needing to live vicariously through their children and want their car.....whoops, I mean their kids car to win even though they are cheating and their kids are only learning that dad does the work.

heres the car the boy and i made for him he took 4th place but he wanted a real looking car so we did it up as we are/were big dale fans ! ! than the red white and blue car was mine from the 70's that me and my dad made i took 2nd with it !just have fun with it ! winning isnt everything ! but memories last forever !

maybe they ought to change the rules and have the kids only work on the cars while they are at their meetings to insure the kids are the ones to build the cars and not their dads. that way they actually learn something instead of that they arent good enough to do it themselves

Gary, that is actually a very good suggestion. While a Bear Den Leader/Cubmaster, we did just that. I had the whole Den over to my place and we all went over the rules, how to build them, and the kids got them started. We did a few meetings like that.

We also had a handout we gave out with the cars that had the rules for BSA and our District on them, as well as some helpful hints. We offered tech inspections for the cars the Pack Meeting before the Pinewood as well. The setup/tech blocks and scales were there so if any last minute problems were found you could correct them.

During the day of the event, not only did we do the full tech of the cars, but we also had a "PIT" area with tools and extra wheels/axles if you needed to fix a tech issue or a broken part.

The key is communication!

maybe they ought to change the rules and have the kids only work on the cars while they are at their meetings to insure the kids are the ones to build the cars and not their dads. that way they actually learn something instead of that they arent good enough to do it themselves

Gary, that's a fantastic idea!!!
I would've thought that having the adult class would've kept the dads' noses out of their kids cars but it didn't help at all. The dads want their kids to win, even if it means cheating.
And unfortunately, your plan wouldn't work because the fat-ego dads would bitch to high heaven if they can't cheat for their kids.

Gary, that is actually a very good suggestion. While a Bear Den Leader/Cubmaster, we did just that. I had the whole Den over to my place and we all went over the rules, how to build them, and the kids got them started. We did a few meetings like that.

We also had a handout we gave out with the cars that had the rules for BSA and our District on them, as well as some helpful hints. We offered tech inspections for the cars the Pack Meeting before the Pinewood as well. The setup/tech blocks and scales were there so if any last minute problems were found you could correct them.

During the day of the event, not only did we do the full tech of the cars, but we also had a "PIT" area with tools and extra wheels/axles if you needed to fix a tech issue or a broken part.

The key is communication! thanks for the post, makes me feel better that there are people doing it right. the kids should be given all the guidance and support they need but they should get the satisfaction of doing it themselves. also they wont feel bad when they do it the right way but some other kid brings one his engineer dad built that would make a gm prototype model look bad

Boy, a lot of stuff here really brings back memories. One thing I didn't see mentioned was "hub caps". These were made with those small circles that are used for pricing at garage sales. Self adhesive and come in different colors. We used these to hold the graphite in the wheels. After initial graphite application and spinning the wheels to distribute, and right before we turn the car over at tech, we held the car on it's side, added as much graphite as possible, and then stuck on the "hub cap". If I remember correctly, speed was actually faster after first round.
As with all these suggestions, check your packs ruls. Good luck!!

Gary, I realize I come off pretty harsh, but Scouting is very close to my heart. Really, common sense and sportsmanship are the key ingredients. Don't ask me about sitting on Eagle Board of Reviews - I'm a VERY tough board member, and for good reason. This award should never be a quick and dirty deal.

I ran our Pinewood for 4 years as a Cubmaster and came back for 2 more to run it after we went into Boy Scouts. Our Pinewood was incredibly organized and ran like clockwork. The District one was actually a letdown after ours!

We did use TrackMaster for the timing/scoring and it worked great. I set the rules up so that the kids got a minimum of 6 runs before being eliminated. No sense in a kid only getting 2 runs after all of that work. Even with a large Pack, we ran the whole shebang in under 3 hours. How? First, we setup the night before and did a dry run through everything...s/w, timing, etc. I then entered the entire Pack into the s/w ahead of time, and when they tech'd on Saturday removed the ones that didn't show. I brought in my laptop and a projector so the results were viewable by all in attendance. My asst. Cubmaster is a TV producer, and he MC'd the entire event. He was hysterical and kept the kids into the entire thing. I would have my Chevelle in front of the doors on display, and we decorated the gym where we held it with racing banners and flags. Amazing the stuff tire stores and oil change places will give you for this!

One big thing is if you can, have an extra track for the eliminated kids to run. We had an old track setup that the kids got to run on after they lost. We would give them their cars back if they were out and they got to run them as long as they wanted. No timing, just first one across the line won. They LOVED that! I think some cars saw about 50 runs by the end of the day on that track!

A few more pics of our layout:

Computer/Printer/Projector:
http://www.rmsresins.com/photos/pinewood/computers2.jpg

The Pits:
http://www.rmsresins.com/photos/pinewood/pits2.jpg

Friday Night setup - me in the shorts:
http://www.rmsresins.com/photos/pinewood/track2.jpg

Just after opening the doors on Saturday:
http://www.rmsresins.com/photos/pinewood/overallpic.jpg

This thread is morphing a bit... what started as car building advice has grown into event running advice. All good though.

I too started having car building den meetings. One side affect is it increased interest and participation in the open house building sessions.

One of the best things I ever started doing is having car check in on the Sunday afternoon before the race (held on a weeknight). This allowed time to handle adding weight or changing out illegal wheels/axles. Moms bringing the boy and car for checkin really appreciated the extra assistance. BTW the cars store VERY well in zip lock baggies. The baggies can be closed with a bit of air inside making pillows to protect the cars. Simplifies storage and transport of the cars between checkin and the race :thumbsup:

Having a second track for "grudge racing" adds a lot to the event if you can do it. I also made up kits for car display stands that the boys had to put together themselves. Having some kind of activity for boys not racing at the moment adds a lot of enjoyment for all to the event.

One counter point to the angled wheels suggestions is to consider where the wheels may rub. If you put negative camber in the wheels they will rub the center guide strip much higher and with a lot more friction.

Also on the weight it matters not where you add the weight. What matters much is where the car balances. That balance point should be about 1" in front of the back axle. Just enough on the front to keep it on the track but as much towards the back as possible. For some designs it will be necessary to hollow out the block in the front to shift weight to the back.

The boy/dad contribution is a religious debate with no winners. I believe ultimate truth is in the memories created. If the boy comes out with good memories, then a good balance has been achieved. If the boy treasures each of his creations then dad was probably not *too* involved ;)

Back when I did this, my grandfather did the rough cuts, and I did the finishing... we polished the axles and added graphite, but that was about it...

solder/lead added to the middle...

I was fortunate, as I won our local (10+ packs) event, and went to a regional final (that was about 12 miles away, so not sure how big it was... I do recall 1st-2nd and 3rd from the local were invited, but still probably 100+ kids...

I was disappointed, as one lane of the track had a slight advantage. All heats were "Best of 3", with only 2 cars running... About the first 30 races, the winner won in 2 races...

Mine was the first race that day, where we used all three races to determine a winner... A little disappointing since I won a coin toss for lane choice, and was unknowingly going to choose the faster lane. However, the "starter" asked the other kid which lane he wanted...

Unfortunately, the other kid won the first, I won the second (switching lanes to be fair), but he won the third (back in the faster lane)...

The cars were really closely matched though...

Still have my trophy and car sitting on the shelve...

Back from the dead...

I'm building one with my younger son, race is this weekend.

We looked at a "secrets" book at the hobby store, and he chose a wedge design. We bought the wedge kit with 4 tires and axles.

Wheelbase has been lengthened about 1". Car sits at 4.9 oz. right now, with cylindrical tungsten weights set over the rear axle so that COG is between 1" and 3/4" inboard of the rear axle.

We have to prep the "drivetrain" this week, and it will be ready for race day. :D

Watch out!!! The kits you buy in the store will get you disqualified, everything must be BSA approved, even the wheels have BSA stamped on them.

Jonathan, this is what we bought...

http://www.revell.com/pinewood-derby/images/large/rmxy8660.jpg


From here: http://www.revell.com/pinewood-derby/rmxy8660.html

Do the wheels have BSA on them? If you win the Pack and go to the district this is very important. Here is a link to the wheels and axles:

http://www.scoutstuff.org/official-pinewood-derby-wheels-and-axles.html

The link I posted above shows that Revell is an Official Licensee for BSA. These kits are legit...:D I'll post a pic of the car later.

Great!!
Trust me, I have seen great cars disqualified. I am sort of glad I am in Boy Scouts now, Cub Scout parents can be brutal when it comes to racing. The Pack my kid was in rigged it so the Cubmaster's kid won everytime, he staged the judges in the most original and best looking classes.

Lube those axles with graphite and eliminate front wind drag with shape.

PWD is all about energy management:

1. Which car has the most energy to begin with. Think "potential" energy here. This is maximized by making sure the car is as heavy as the rules allow and that the weight is as high as possible. Having the car CG too far back makes the front end bouncy and it can derail. Thus the recommendation of 1" ahead of the back axle and the advantage of moving that back axle as far rearward as possible.

2. Which car has the most energy crossing the finish line. Think "kinetic" energy here. Going down the ramp you convert potential energy into kinetic energy, so the amount of potential sets the maximum you can get for kinetic. The trick is then to NOT lose any of that precious kinetic energy to friction. Most do not realize that the #2 top source of friction is the center lane guides steering the car. Insure the car rolls straight and the inside edges of the "tires" is smooth (some may have a molding flash on them).

Those two things will get you very close to the top of the pack... along with basic axle detailing and polishing :beers:

I run about 1-2 PWDs every year on a track I built almost 10 years ago. I use computer timing/scoring giving a precision down to 4 decimal points. There have been many races that would have been way too close to judge using the MkIX eyeball. I had a race heat at the last PWD where two cars had the EXACT same time on the computer. First time I have ever noticed/seen that. Fortunately the total time for those cars over all three lanes was different ;)

http://i812.photobucket.com/albums/zz42/jlk72355/2012-02-10_06-36-40_986.jpg

http://i812.photobucket.com/albums/zz42/jlk72355/2012-02-10_06-37-09_403.jpg

http://i812.photobucket.com/albums/zz42/jlk72355/2012-02-10_06-37-44_14.jpg

All ready for Saturday. :D

My son's car flew off of the end of the track into the wall. After that I got nervous but because he was crying after the car got messed up paint wise the judges never looked at it and put it back in line. Whew that was close!! LOL

On the tied cars did you run them backwards for the tie breaker?

PWD is all about energy management:

1. Which car has the most energy to begin with. Think "potential" energy here. This is maximized by making sure the car is as heavy as the rules allow and that the weight is as high as possible. Having the car CG too far back makes the front end bouncy and it can derail. Thus the recommendation of 1" ahead of the back axle and the advantage of moving that back axle as far rearward as possible.

2. Which car has the most energy crossing the finish line. Think "kinetic" energy here. Going down the ramp you convert potential energy into kinetic energy, so the amount of potential sets the maximum you can get for kinetic. The trick is then to NOT lose any of that precious kinetic energy to friction. Most do not realize that the #2 top source of friction is the center lane guides steering the car. Insure the car rolls straight and the inside edges of the "tires" is smooth (some may have a molding flash on them).

Those two things will get you very close to the top of the pack... along with basic axle detailing and polishing :beers:

I run about 1-2 PWDs every year on a track I built almost 10 years ago. I use computer timing/scoring giving a precision down to 4 decimal points. There have been many races that would have been way too close to judge using the MkIX eyeball. I had a race heat at the last PWD where two cars had the EXACT same time on the computer. First time I have ever noticed/seen that. Fortunately the total time for those cars over all three lanes was different ;)

On the tied cars did you run them backwards for the tie breaker?

I use a computer timing system. The software schedules each car to run once in each lane of the track. The winners are determined by total time of all of the lane runs. Have never had a tie at that level with 4 decimal points of computer timing precision :thumbsup:

It is NOT uncommon however for a boy to decide to run his car backwards for one or more of his runs. I have the boys do all of their own car handling. Builds ownership, involvement, and responsibility. Also minimizes accidents and dropped cars. I have dropped one car over the years and it was when handing off from me back to the boy (he put his car on the track before it was his turn). I felt awful and reminded myself to NOT do that again :yes:

Here is my , Er I mean our attemp at a PWD car - 2 years ago - 2nd fastest (but nicest paint :thumbsup:)

LK

http://i925.photobucket.com/albums/ad96/alwhite00/pwd.jpg

Well, he weighed in at 4.75 ounces last night and added a .25 weight right on to the "rear bumper"...racing right at 5.00 on the nose.

He won first place in his class, and took second overall in the pack. First place beat him by a hair, at only 0.001 seconds. He will race in district finals in a few months!!!:hurray::hurray::hurray::hurray::hurray:

Not bad for a Tiger Cub in 1st grade. I'm proud. :D

Congrats Highway Star and son!

My son and I partookin our first Pinewood Derby today, too! He's a Tiger in the first grade ,too! Thanks to some tips here he nabbed a second place finish in his pack, but in the Den Championship, he finished 8 out of 12. We're really proud of him though! What a lot of fun! Hats off to all those who make this event possible. We'll definitely be back.

http://pic60.picturetrail.com/VOL1734/11053511/24023955/400982685.jpg

I tried not to help too much, but I did use a saw for 2 cuts on the block. He sanded it, and I showed him how to spray paint the base color green. I masked off the stripes for him to paint on the sides. I drew the outlines for the "windows" in pencil, and he painted them in. We opted to print off some "stickers" of his choosing, he placed them,except the roof, and we clear coated the snot out of them (spray can) to get them to stay down. We both polished the axles ( I spun the drill and instructed) and I had to help him getting the axles in the slots. Then we tested it, and I showed and helped him how to "align" it to get it running straight (until he got a little exasperated). I drilled the hole for the weights after we discussed where we should place them, and thanks to the Misses' digital food scale, we were within a 10th of an oz (over) on weigh in. We drilled a few holes and we were ready to go.

Overall, I don't think you could ask for a better father/son project growing up. I wish my dad and I were able to do this.

My tips:

As repeated: Polish them axles! Remove them cast marks! They should be like glass. Bevel the nail head slightly. USE LOTS OF GRAPHITE. You're gonna get dirty on the last, and so will the car. Do it outside or lay down some newspapers. Keep a rag handy. :D

TEACH the boys why they should do what.

Weights: We front weighted our car. We figured it'd be a better pull off the starting dowels, and we also got this advice from a relative. Physics may argue differently, but we had a good first showing nonetheless.

Trial and error... have fun and see you next year! :hurray::D

Over the year I have noted that the younger the boy the better the cars tend to do ;)