Pine Wood Derby

[CHRIS67]

It's Pine Wood derby time for the Cub Scouts. I let my son build his car and we got spanked last year (our first year) in the derby coming in 32nd out of 34 kids. Deciding that 98% of the other parents built the cars for their kids this year I did the same. I done a lot of legal modifications I'm thinking that I have a top 10 car. I've extended the wheelbase, grooved and polished the axles with 6000 grit paper, put as much weight as possible in the rear without lifting the front wheels, trued the wheels, coned the inner wheel hub, and broke in the wheels with graphite. I have about 30 hours into a 6" wood block.

Is anyone else building a car for their Cub? Any success stories?

[Samckitt]

I hear about that every year from a guy I work with. My son is not old enough for that yet. On one hand I feel that this is something the kids should be doing themselves, then I think it is good time for the father to spend with the child(ren). But most of the time it turns into a project that the parent works on, not together with the child.

[69Nova]

Got any pictures of the car?

[CHRIS67]

I'll take some tonight. My son did the painting and loaded it with stickers. Is there such a thing as a Pine Wood sleeper?

[parsonsj]

Sounds familiar. My son and I got better each year, and almost made the regional finals our last year. In general, he didn't care as long as he didn't lose to ALL of his friends, and worried mostly about paint and stickers. It was my job to keep the wheels from falling off.

His pack didn't go overboard on making the event ultra-competitive, so it was a good balance.

jp

[Jim Nilsen]

More than once I saw the kid that just bought the kit and just glued it all together and won the whole pack. You sure went to a lot of work. Dry film lubricant is better than graphite in most stuff i have ever worked with when you need a dry lubricant. The weight is really better right in the middle and maybe just a little forward to keep down wheel vibration up front.

It will be interesting to hear how it goes.

If you teach a kid how to do it with pride ,patience , and the understanding that you are doing your best and that is good enough for a pinewood derby car . Sometimes it is not all about winning but how you learn to deal with losing and go on not feeling you got cheated by someone else. It sure is fun to win if you can because the moments are rare when it comes to low tech odds.

Also make sure your boy can tell everyone what has been done to the car so he will feel better about himself when you talk about it with others .

Think SPEED

[vanzuuk1]

Chris has your son even seen the car?

[CHRIS67]

Chris has your son even seen the car?

No, I kept him blind folded when he was working on the wheels and painting it.


I don't want to be that Dad who does everything for his son and the boy doesn't learn anything from it; there are a few of those in the group already. I used the power tools and told him what I was doing along the way. There were times when he had enough of the car and I'd end up finishing, but all in all we did it together.





This year's wheels

[69Nova]

All I see is red X's

[CHRIS67]

Uploaded fine and previewed OK.

[amx2334]

Last years before paint.


This year it will just look like a hockey stick. I want to make the front where the car sits against the starting pin as high as possible-this way the car starts rolling sooner as the pin moves.form follows function.Personally I think its all in the alignment.

[CHRIS67]

Last years before paint.


This year it will just look like a hockey stick. I want to make the front where the car sits against the starting pin as high as possible-this way the car starts rolling sooner as the pin moves.form follows function.Personally I think its all in the alignment.

Good idea, now I'm thinking about putting a small "spoiler" on the front up high out in front so it rolls first. Thin out those wheels and cone the hubs to come off the line faster than heavier wheels
Alignment is big, but so are friction and weight.

You want the majority of the weight in the rear of the car, but ballanced 3/4" to 1" in front of the rear wheels to keep it from bouncing on the front end. Keep the weight of the car on the hill as long as posible to push it down the track.

[amx2334]

our official rules state:
2) Only official BSA wheels and axles that are provided with the car kit may be used.

3) No "machining" of wheels other than to remove molding imperfections is allowed. Wheels may not be machined to reduce the contact of a standard wheel surface with the racing surface.

I machined the axles and coned the hubs.i am thinking of a wave type axle (think ARP wavelock rod bolts).i tried to get one front wheel up a little so it rides on three.still gotta go straight though.i did notice that our local rules dont say anything about "dry lube only" like the rules in the box.HMMM-time to put on my Smokey Yunick thinking cap.If it ain't in the rules it must be legal right?
i volunteered to help set up the track the night before. hoping to get a little track time in.i may make the weight adjustable front to back and see what the effects are.putting the weight up high only helps on a steep track.ours is pretty low.

Good idea, now I'm thinking about putting a small "spoiler" on the front up high out in front so it rolls first.

be sure to put an arrow or something on it to show which way is forward.

[CHRIS67]

our official rules state:
2) Only official BSA wheels and axles that are provided with the car kit may be used.

3) No "machining" of wheels other than to remove molding imperfections is allowed. Wheels may not be machined to reduce the contact of a standard wheel surface with the racing surface.

I machined the axles and coned the hubs.i am thinking of a wave type axle (think ARP wavelock rod bolts).i tried to get one front wheel up a little so it rides on three.still gotta go straight though.i did notice that our local rules dont say anything about "dry lube only" like the rules in the box.HMMM-time to put on my Smokey Yunick thinking cap.If it ain't in the rules it must be legal right?
i volunteered to help set up the track the night before. hoping to get a little track time in.i may make the weight adjustable front to back and see what the effects are.putting the weight up high only helps on a steep track.ours is pretty low.

be sure to put an arrow or something on it to show which way is forward.

Our pack's interpretation is you can not change the footprint of the wheel, ie. cutting a grove so less of the tire is in contact with the track. However you can sand down the official wheel to remove the injection mold and true the wheel thus reducing the overall weight of the wheel.

Maybe your pack's interpretation is different. I help set up the track too, but pack our rules state that we can only use previous year's cars to test the track.

One last tip that seem to help the winning cars last year. Break in the wheels once you have them on the car, spin them while watching a movie and every so often put a little more graphite onto the axles.

[parsonsj]

spin them while watching a movie and every so often put a little more graphite onto the axles.

Consensus among the pack daddies last year was that this was the most important thing to do. I had my son do it for hours while he watched TV.

jp

[TonyL]

I ran my car on a belt sander with a really fine grit on low speed for hours adding graphite as it rolled. (I wish i had shots of that car. It was sweet.)

another sweet trick is to polish the axles. The rules say you have to "use" the axles. but if you remove a few hundred thousands off of them well..

A big part of friction that gets overlooked on a pinewood car is the area behind the brad end of the axles, make sure that area gets deburred or polished where it contacts the center of the wheel.

edit. here's where we learned it from

THE most important aspect of building a fast car. First, we take the axles and a small fine round file (you can get these at a hobby shop or hardware store) and file the casting burr from where the nail shaft meets the head. This may seem tedious, but it really makes a difference. Next, we place the axle (pointed end first) into the chuck of a cordless drill or Dremel tool. Take a piece of medium or fine grit sandpaper and tear it into 1/4" wide strips. While the scout holds the drill (don't forget your safety glasses), the parent/helper bows the sandpaper in a semi-circle around the axle. As the drill turns the axle, the sandpaper smooths it down. It's important that the axle is centered in the chuck of the drill to maintain accuracy and roundness. Don't apply too much pressure to the sandpaper or it'll snap in half. Trial and error is the best advice for this step. Next, move to finer sandpaper and repeat the process. Repeat this process with coarse steel wool, then fine steel wool and finally, ultra fine steel wool (you may have to clean off the steel wool fibers that get wound around the axle between steps). Finally, the axle should be fairly well polished, but we're not quite finished... the final step involves taking a 1/4"x4" strip of CLEAN cotton cloth and applying some car wax (or chrome polish) to it. Repeat the same process as with the sandpaper and steel wool until the axle is buffed to a high gloss. Use a clean, dry cloth to remove any wax residue from the axle. This may seem painstaking, but it WILL make a difference at the Finish Line!

[amx2334]

I do it while reading pro touring threads.Hours and hours and hours.
Funny thing is last years winner said " I had no idea what I was doing. We just slapped it together one night." I saw the car and I believe him.Won by a couple hundreths of a sec.

[Jim Nilsen]

I do it while reading pro touring threads.Hours and hours and hours.
Funny thing is last years winner said " I had no idea what I was doing. We just slapped it together one night." I saw the car and I believe him.Won by a couple hundreths of a sec.

My family was in scouting for 20yrs and i have seen it so many times that you would place bets on the cars that were just blocks of wood and the full amount of weight.

After having dealt with injection molding machines and molds, if you are lucky enough to get the right set of wheels that are really to spec you are probably a lucky person. Molds tend to wear out in irregular fashion depending on how the sprew is placed. The pins that form the axle hole can wear,break,get stuck and broke and several other wear ploblems that occur and then a new pin will be intalled and the other worn ones will still be there. I bet there is at least a 20 to 30 mold or bigger making them and all being dumped into the same tote to go for packaging. Now if you just knew the size of the nail too!!!! I have always wondered what the actual size of the nails and wheels /clearance works the best right down to the .0005 . A lot of work for a Pinewood Derby car.

Try the car backwards just pushing it and see which way it turns vs going forward. good way to check the alignment.

Goodluck

[TonyHuntimer]

My Dad had a lathe. He cut the wheels so that only a very narrow part of the wheel was left to touch the racetrack. We also did everything else you said that you did. We got first in the troop and first in a second event at a Jamboree (or something...it's been a while). I still have it and the trophys somewhere.

Tony Huntimer
RaceHome.com

[shortrack]

make it run on 3 wheels.......make one of the back ones not touch.....less drag

kinda brutal but saw one where they simply painted the raw rectangular piece of wood up to look like a school bus and ran it.....looked like a brick.....took 2nd place