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Minimizing Rolling Resistance

Tip: Details Matter: A well-built car can be slowed to a snail’s pace by carelessly positioned screw eyes. Make sure they don’t cause the guideline to bind on the car.

What is rolling resistance? It is simply the force that is resisting motion when the dragster rolls on the track. While there will always be some resistance due to friction, such as between the wheels and axles or the axles and car body. However, there are things that can increase it in a dragster. Test for spinning friction by rolling your car down a ramp and observing how far the vehicle travels. Though less scientific, another method is to spin the wheels while holding the car in an inverted position and note the time it takes for the wheels to come to a stop.

Experiment with different bearing materials or use a lubricant such as dry powder graphite to improve performance in this area. Make sure that your tires aren't deformed. The issues below are also potential sources of rolling resistance – test for each one:

  • Improper wheel alignment – This happens when axle holes are not drilled straight. Stated more precisely, straight means the holes should be perpendicular to the car’s longitudinal axis. Roll the car forward on a flat, smooth surface; it should go fairly straight. If the car veers drastically to the right or left, there’s a good chance the wheels are misaligned.
  • Careless location of screw eyes – If a screw eye is poorly placed, the guideline can drag on the body or wheels of the car as it moves down the track and cause a great deal of friction. Invert your car and thread an 18-inch length of monofilament (fishing) line through both screw eyes. Pull the line taut and move it back and forth. If the movement of the line is restricted, consider relocating one or both of the screw eyes.
  • Wheel imperfections – Small imperfections from the molding process might be found on the rolling surface of a wheel. Examine your wheels and carefully remove any imperfections with fine-grit sandpaper. You can also use a wheel lathe to ensure the wheel is properly shaped.