Building Winning Pinewood Derby Cars 

Prepare the Axle Supports (holes) in the Block
The axle slots or holes must be square with the block. Using a drill or drill press, drill new axle holes using a #43 or #44 bit (#44 is the axle size for the new 1998 kits). We use the #43 so that the axles easily fit into the axle holes (Later you will see how we secure the axles into the holes -- all this makes it possible and easy for the scout to install and secure the axles/wheels). If legal under your local rules, lengthen the wheelbase -- the longer wheelbases seem to be more stable. I also drill the right front axle hole higher to lift the right front wheel off the track (3 wheels, rather than 4, means a slight reduction in friction, but more importantly, it provides a place to put your worst wheel. It seems there is always at least one really bad wheel in the kit).

What you want is wheels that run true on the axle 
and "absolutely" do not rub the car body when running.

Build glue application channels for gluing in axles. This is simply drilling a 3/32 hole or cutting a slot from the bottom of the car into the axle channel. This makes it real easy for the scout to secure the axles in with a drop or two of glue after all construction and testing have been completed.

Build graphite application channels for lubricating the axles and wheels. This is simply grinding or cutting away a small area of wood on the bottom of the block below the axle. It makes it much easier for the scout to apply graphite to the axles and wheels after all construction is completed.

Create weight storage compartment
Pick your weights ahead of time and make a hole(s) or pit for the weight at this point. You will probably be adding from 1.5 - 2.3 ounces of weight. You can put weights in anywhere, but the experts say the weight placement should be biased toward the back of the car making the balance point 1" to 1 1/4" in front of the read axle. I totally agree with this weight placement. The images below provide what I consider to be the best idea for weight placement. The holes for the weights (3/8") are drilled to accept standard tubular weights available from your local Boy Scout supply store. This way the scout can safely participate in adding weigh to his car. A few drops of glue will hold the weights in and you can putty over the holes before painting.

Build the car body
This is where any age kid can get really involved and have lots of fun. Keep the car shape as simple as possible so the kids can actually help do the work. Apply the design to the block, carve (not for kids), saw, sand and paint, etc. The kids can really have fun here and, for the most part, will not negatively affect the performance of the car. Just a couple of tips here: (1) Make sure to take off a good bit off wood, because you will want to control the amount and location for added weight. (2) My fastest cars are the ones with the skinniest and slickest profile.

Minimize rolling friction
True and polish the wheels and axles.
(Remember, one wheel is going to be off the track, so pick the best 3 wheels and axles to start with. You can roll the wheels on a glass table & spin the wheels and axles in a drill to find the best ones) You can really have some fun with the scouts when testing the wheels on a table. It's like a race in itself.  Do not alter the basic shape of the Boy Scout kit wheels -- you only want to remove any imperfections and smooth up the finish.

True and polish the wheels using a drill and vice setup. You clamp the drill in the vice and spin the wheels using a wheel auger (available from your Boy Scout supply store). True the wheels to round using a small flat file then polish with a 1500 grit wet-sand paper. Make sure you keep the paper wet -- this cools the work and also provides an exceptionally smooth end result.

The axles require special treatment. A drill/dremel drill press setup is required for all steps. Using a very fine ignition file, remove the flashing from the inside head of the axle and shaft (this is where you will want to create the angle on the inside of the axle head). Polish with the 1500 grit wet-sand paper and finish off with chrome polish and a soft cotton cloth.  

Finish construction
- Weigh all car parts and get the car to the right weight and finish off any needed sanding, painting, patching, detailing, etc. The scout can do most all of this with very little assistance. You do not want to have to do any of this type of work after the car is assembled.

- Rub graphite on the car body where the wheel hub runs against it. Rub it in really well. Enough will stick to provide a really slick surface for the wheel to rub against if the wheel happens to hit the car body during the race. The scout can do this with minimal assistance.

- Insert the wheels and axles into the axle holes (do NOT glue yet). We use a tongue depressor (1/16" - 3/32" thick) to set the wheel clearances. The scout can do this easily, since you prepared the special axle holes!

Wheel clearances are critical! You want plenty 
of slack for the wheel to move freely.

- Test the assembled car (no glue yet) on an inclined table -- glass is preferred. Test your new car against the baseline (last year's fast car). The table test will not tell you which car will be fastest on the track, but it will help you "tune" your car to be as fast as possible. The scout will really enjoy this part (as long as you don't over do it). If you have access to a track, do final testing on the track before the race.

- If you have to take the wheels off for any reason. Mark the "top" of each axle and put the wheels and axles into baggies labeled LF, RF, LR, RR. This makes sure you get the wheels and axles back onto the car in the right position. You will want to have some graphite in the bags also.

- Apply glue in the glue application channels to secure the axles. If the scout is careful, he can do this with minimal assistance.

- Continuously force graphite into wheel and axle areas and spin them till they are worn in really well. Also rub graphite onto the wheel itself. You can't put too much graphite on -- any excess will just fall out and blow away. And, you can't spin the wheels too much -- the kids are great at spinning the wheels.  

Tuning -- Axle and wheel alignment
A really fast derby car must have true running axles and wheels. Sometimes this happens by accident, but it is best to make sure the axles and wheels are running true by tuning the car. The scout can have some fun here but not if it's over done. Dad can do some tuning and the scout can do the kitchen table races. Some of the links below go into great detail on axle alignment, but we found these to be too detailed for either me or my son to follow. The use of wax paper shims might be o.k., but only to correct a really bad axle problem -- aligning all axles and wheels using this method is difficult and boring. I doubt you would ever find a scout that would consider this a fun exercise.

Note: There are several sources for specially tuned axles and wheels -- most of these special components would be in violation of local race rules, so don't even consider it. If you and your scout can't do the work yourself, what would be the point?

The idea is to have a car that is in near perfect alignment. Meaning that the car runs basically straight and that the wheels do not consistently ride against car body or axle head (especially against the car body!)

Some of the things you can do to tune or improve the alignment are:
- Go back to square one and make sure to start with good axle supports.
- Make sure the better of your wheels and axles are being used.
- In some cases switching your axles and wheels around may help.
- If you have a wheel that insists on rubbing against the car body while rolling, use the wax paper shims to shim the axles "up" | "back" | "up and back". (See axle alignment links below).
- If you have a really bad wheel, re-polish it and try again.
- Continue to roll assembled car and adjust the wheels and axles until you have a car that runs true. Continue to test it against your baseline car in a mini kitchen table race.

List of Things That Really Appear to Help

List of Things That Appear Not to Really Help - Glue bead (covered with graphite) on body for wheel to rub against.
- Angled axles? (Again, not quite sure on this one). Actually this is one of the biggest boosts -- we were hoping you would not read this far. Drill the axle holes in the body at a downward angle of like 1 degree. This forces the wheels to "ride up" toward the axle head where it encounters much less friction that what it does when the wheel rubs the car body!
- Polishing axles with graphite pencil.
- The use of hubcaps.