Pinewood
Derby
Tips & Tricks
Want to make your car faster? We've
put together some Tips & Tricks
to help you get an edge on the competition.
- Keep the car
a full seven inches. It has to do with the physics of velocity and length
of travel of the weights.
-Use the full
2 3/4 inches (outside wheel to outside wheel) that the rules give you.
This will allow the wheels to travel farther before hitting the center
strip.
- Leave a lot
of wood in the back to put in the weights.
- Use the groove
closest to the end of the block of wood as the rear axle.
- Do not make
the front of the car pointed. It is hard to set up against the starting
dowels
- Debur the wheels.
Take off the flashing and seam that was produced when the wheel was molded
with a 600 grit or better sandpaper. Inside as well as out. Sand any bumps
off the wheel the sandpaper. Metal polish will restore the gloss. Be careful
not to break any rules your race has regarding wheel modification. Don't
sand too much or you'll create a flat spot. Sand by hand not in the drill.
Heat from the high speed of a drill will damage the plastic wheel.
- Polish the axles.
First with a 400 grit if you have a really bad spot. Then a 600 grit,
and then a jewelers rouge. Finish off with a chrome/metal polish.
-Have only three
wheels touching the track. Raise a front one slightly. There is less friction
with 3 wheels rolling than 4.
-The head of the
axle should be tapered about 15 degrees so it rubs against the wheel less.
- Wax the wheels
with furniture polish. Make sure the polish does not contain a solvent
of any sort.
-Use graphite
only. Oil damages the paint and collects dust.
-Break in the
wheels by spinning them with lots of graphite.
-Put a small drop
of white glue where the axle goes into the car body and put powdered graphite
on it there. That causes less friction if the wheel should rub against
the car body.
-Other than the
good polishing of the axles, dump the axles and wheels in a ziplock bag
with somegraphite and shake them for a few days prior to the race. That
way the wheel and the axles are as slick as can be.
-Put the axle
in at a downward (5-10 degrees) angle. This provides two benefits. The
first is the only the inside edge of the wheel is in contact with the
track. This seems to make the car go straighter with less wobble. The
second benefit is that the wheel rides to the outside of the axle and
doesn't come in contact with the body.
-Axles must be
in straight front to back. That is square to the body. True the axles,
don't trust the slots! If you have one, use a drill press to ensure all
axles are straight. One of the front and two of the back should be measured
to be the same height.
-After pressing
in the axles, test the car for crooked wheels...roll it on the floor.
If the wheels are on straight, the car should roll 8-10 feet in a fairly
straight line. Should the car turn left or right, you need to tinker with
the axle placement without removing them from the car body, until it rolls
straight.
- Do not put the
axles in at the top of the groove. Put them in at the middle. This lifts
the car of the track a bit more and reduces the chance of rubbing on the
center strip.
-Get the weight
as close to the 5 ounce limit as possible.
-A car with more
weight to the rear generally grabs more speed down the slope.
-Tubular weights
can be sunk in the sides; flat weights, like those sold at hobby &
council stores can be attached to the car bottom if it is carved in a
bit. Incremental weights ( with pre-marked grooves) are easier to snap
off into the size you need. Some folks just use BB's, nuts & bolts,
etc., but these must be glued so that they can not move. No movable weights
or mercury are allowed.
-Keep the weight
low on the car and in the center (Left/Right of the car). Put the weight
just in front or behind the rear wheels for less wheel chatter.
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