These things are so cool....but I have had it.  Weight is right, used all the little "tricks", but still about 0.2 seconds slow.  Not bad but I think I'll polish the axles a little more tonight.  Anybody else gettin ready to race?  Oops, mean, anybody elses KID getting ready to race?

I never did real well making these.  Mine was always the slowest. Boohoo.
Bill3508

I still make them.I am in the process of
building a '69 Shelby GT 350 this year.Last
year I built a '69 mach 1,the year before a '65
mustang fastback.

As you can see I go for the best of show award.
I have won 1st for the last 4 years in a row.The
fellow adult leaders that compete against me
hate my cars and the kids love them.It is a
lot of work,our kits have the axle grooves cut
so you have to know the scale of car you are
trying to build and how much wider for taller
you need it to be.

When I complete my Shelby I might post pics.

You dredge up many good and bad memories. I was in a single parent household, and mom wasn't much of a woodworker, so I had to make mine without any help. It didn't win and didn't look too good, but I was damn proud of it!

My son did/recommend the following:

Car weight should be at maximum limit.  Have some removable weight on the car in case the official scale if different than yours.  Weight is probably the most important issue when building your car

polished the axles

polished wheel hub

de-burred under side of nail head (a.k.a. axle). I turned it down so it was slightly conical to minimize contact area of wheel and axle

smoothed hub area that contacts car body

checked that the axle slot are parallel

weight distribution of 60/40 rear/front.  If the front end is too light the car gets squirrelly, but having more weight towards the rear is beneficial from a gravity standpoint

I used a very low viscosity wet lube, which I’ve been told is against local rules this year.  If you use a wet lube, make sure is compatible with the plastic wheels (polystyrene, I think).  This year my son is going to try a dry lube called Zonyl, its a fine white powder in the Teflon family I believe.  They claim its has the lowest coefficient of friction of any solid.

If you have a car from last year, you can use it to compare the new car.

That’s about all I can think of.

Small surface area? Only 3 wheels touch? Tracks straight on a smooth, flat surface? Polish the axles with crocus cloth, lube with graphite. Absolutely no oils or greases.

My first trophy ever was the Pack 452 Pinewood Derby Champ of '66. It's sitting on my dresser right now. Sent my little brother to the districts... came second. Geez, that must have been '73 or '74? Ah, memories...

I had the ultimate pinewood derby car. It was handed down to me from my cousins. My uncle spent weeks on that thing, Wish I still had it id put it up against any pinewood derby car.

My kids not getting ready to race them just yet but I do know the secret to pinewoods.  it's all in the axle slots and shape. First, the axle slots have to be redrilled by a milling machine to make sure they are EXACTLY parallel. That's the issue with most pine ridge cars, the axles aren't totally parallel and fight against each other.

Second, you need a wedge shape with a slight raise in the tail,  Kind of like a doorstop that turns into a ski jump effect thing. Oh and by ALL MEANS install 30 caliber bullets as the headlights.  You can't use normal weight, you have to use bullets.

With that settup you will be unbeatable.  When I was a kid we had to outlaw the milling option for axles in my scout council because kids who didn't have access to The Site (mysterious nuclear test side in Idaho where the milling operations took place ) couldn't even compete.  So they eventually outlawed it in my council.  But I'm sure it's legal in yours and it's a sure thing.

crash.

I raced three years, took 2nd my first year out, and took 1st place (by a longshot) in my last year.

The year I didn't place, was the year we did all the tricks, sanded wheels, polished axles, chamfered nail heads, even mill-cut the body and added wieght in the right places.  

That car was a dog.

When I took first, and whittled the body out with a pocket knife, and just did the basics.  For weight, I founf some of my Dad's .357 bullets, and I loaded six of them in holes I drilled out in the hood area.  It looks like 6 big carbs sticking up there!  Painted it with some "rub-n-buff" paint I found laying around.  Nothing special, and it was ugly (but I thought it looks cool, and none of that fancy shmancy crap we did the year before.)

That car was untouchable.  I know it would have won State, but I got grounded and couldn't go.

The fancy science is definitely a good thing, but my car had a soul.  That's what made it a winner.

Sorry buddy.....can't help ya.  This year was the Space Derby.  Looked cool as hell, came in last.  Year before was the Regetta.  Gunnutt jr. came in first in that one though!!  

After being beaten by every kids dad in my Troop I got mad and spent about ten months constructing my car with a pocket knife and sandpaper. It paid off. Smoked them all. Should have seen the upset fathers..

Who's racing?  You or your kid?  Like another Poster on here I had to make my own stuff.  It used to piss me off so bad when you could tell the perents made their kids cars.  It got to the point I'd just put my wheels in the block of wood and send it on its way.  

Listen to this man.  I won it 3 times following the exact same advice.  ('cept my Dad told me!)



Probably the most important item on the list.



Probably the 2nd most important.  This is advice that will help you [b]win[/b]!

I helped a friend build one when I worked at the NASA. We consulted several engineers (noshitrocketscientist) and built the absolute aerogoddamit low drag mofo car. It looked like it was built by Lockheed Martin; which it was, and we got beat by a freakin block of squared off chunky pine on wheels! Looks aint everything.Good luck.

I never won anything more than den-level, but my brother won the pack trophy for 3 years, we even had an old two-lane track my grandfater made for his dad so he (my dad) could test his cars when he was a cub scout.

Speaking from my experiences (building our cars was a family thing, all three guys in the family worked on them):
Do NOT use the pre cut axle slots, drill your own, those slots arent accurate enough for the axles, use a drill press or milling machine.  Three wheels on the table is gospel.

Chuck each wheel up in a drill and sand them so that its slightly rounded in profile. That way, only a small line of the wheel touches the track, instead of the whole surface.

To insure your son's car is within weight, have him mill an area about 1/4" deep in the bottom of the car, covering about 1/2 of the bottom surface area.  Take fishing weights and squish them flat in a vice, and then *hot glue* the squished weights and lots of BBs in the area.  If he is over weight, he can use his pocket knife to pop out either the BBs or the fishing weights to lower it.  I always pretested my cars before the race, most I ever had to pop out was 10 BBs.  Those kids that drill, put in lead weights, and fill with wood putty are up the creek without a paddle when they find out they are a full ounce over the limit.

I found that car-shaped derby cars work best.  Mine was like: 1/2" tall from the hood to the windshield area (about 2" long), then about .8" tall in the passenger area (1.5 inches long, curving downward on both sides to meet the sides of the body, and also curved down on the front and back of this area, from the center of the compartment, if the curvature was function f all would have f' < 0 and f'' < 0), then a few more inches and a spoiler thats the same height as the body compartment, if not a little lower (again, if curve f and starting from the car body: f'>0, f''>0).

Dry powdered graphite is the best lube out there, but use it VERY sparingly, a little goes a long way.

Kharn

Drilled new axle holes, polished axles, three wheels on ground, smoothed wheels in drill, 4.99oz on official scales, graphite lube.  Think I need to work the axles a little more, especially inside head. Tracks straight on flat surface.  By the way doorgunner, it was my boy and me working together, but he is just a Tiger Scout, so I did all the machine work, he helped with sanding, painting, design (I did lay final paint though).  Here's a pic...
[img]http://community.webshots.com/storage/1/v3/9/64/67/29496467TVrnpcTkuJ_ph.jpg[/img]
Oh yeah, .44 mag brass for tail lights.

Dammit, pic aint working.  Try again.
[img]http://community.webshots.com/storage/1/v3/9/64/67/29496467TVrnpcTkuJ_ph.jpg[/img]

I had a winning car too.  It was almost a block of wood on wheels.

The only thing I did to it, besides paint it, was to lop of the top front edge at a 45 degree angle.

Kinda looked like a minivan.

Took less than 30 minutes to make, painting included.

I probably would have made a run for the next level champs but the guy at the scale was an idiot.

He made us drill holes, fill them, empty them, etc.

Took away the magic from my block of wood.

(In my best Montgomery Burns voice)
[}:D]Excellent....

This thread has certainly been copied to my HD for future reference! My son got his kit last night!

How does the "three wheels touch" tactic work?  Do you just mount one wheel a little higher in the body so it doesn't touch the ground?

I assume that the non-touching wheel goes in the back, right?

We used to insert a toothpick (or thinner) shim under one of the front axles.  It reduces the rolling friction by 25%.  I do remember getting a dirty look from one of the officials one time when I had just put graphite on the axles and spun the wheels to work it in.  He grabbed my car from me and set it on the track.  Three wheels stopped, the front LH one kept spinning.  At that tender age, the dumb look from me must have looked pretty natural..[:D]
He never said anything about it.

Remember to take out the http://

Edit: hmmm, guess it is something more serious. [;)]

Damn, you guys must work with some very loose rules. Almost everything you suggest is explicitly addressed as prohibited in the rules provided by my son's pack.

Last year was his first Pinewood Derby and I was amazed at the woodworkng skills of 90% of the 6 and 7 year olds! It was incredibly impressive how they were able to do so much fine work.

I doubt more than 10% of the scouts under 12 were the primary builders of their cars.  It's a shame that parents have to get so involved that the kids don't even get to participate.

DavidC,
 My derby days were some 29 years ago.  I'm sure some of the rules have changed by now.