The Final Adjustment
This should be your last and final adjustment for your fast pinewood derby car. Many people shove the wheels and axles into the slots and think they are done with the car. Without good alignment it doesn't matter what else you have done to the car, it will not be fast with poor alignment. The wheels will rub against the rail on the track and cause major friction that will slow it down considerably.
The most simplisict way to align a car is to put a long strip of masking tape onto a smooth table and roll the car down the tape to see how straight it goes. You want your car to go as straight as possible, unless you have built what is called a "Rail Rider". A rail rider car is a little more complicated so we'll stay with trying to get the car to go straight.
Once you see if the car veers to the left or right you can start making adjustments to the axles. You want to see if you can adjust the axles without having to bend them. Because once you bend an axle you can't go back without replacing it. Start by adjusting the front axles first. Take a small magic marker and mark all the axles with a small line pointing to the 12:00 o'clock position just like a clock hand coming from the middle of the head of the nail. This will help you know where you are at when you turn the head of the axle to adjust.
Turn either the right front or left front axle 1/4 of a turn and then roll the car again and see what results you get. If it still veers the same direction then try turning the other axle a 1/4 of a turn. Keep turning until you get a different or better result and try to get it to roll as straight as possible.
Work on the front axles until you can not make the car go any straighter. You now need to start adjusting the rear axles. If your car veers right then check to see if the left rear is turning out or right rear turning in. Adjust the one that looks most obvious and then test drive again. Experiment until you can get the car to go as straight as possible. Try not to turn the axles too much as you may loosen them in the slots.
If you absolutely cannot get the car to go straight then you may need to bend an axle to correct the condition. Find the axle that causes the most problem and put it in a vise, leaving about 1/4" out of the jaws. Using a small screwdriver, close to the head, tap lightly with a hammer. This axle will now be very aggressive in adjusting the alignment so make sure you bend the one that is causing the problem and adjust until your car goes straight for several feet.
Once you are done with all alignment adjustments you may want to white glue the axles into the slots taking care not to let the glue get into the wheel. You don't want an axle to come out during the race.
There are more advanced ways to get your alignment dead on, but that takes a special tool and a drill press. You are most likely looking for the cheapest route to build your car and the process above gives you that route. Alignment will make or break your car from being a winner so put some time into it and you'll be happy with the results. Now you know more than most pinewood derby car builders, just with this one tip!