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Pit Stops

Knowing Pit Road Speed in the Rain

This weekend, we learned that the real weather challenge for the NASCAR Nationwide Series isn’t rain. It’s not enough rain. It wasn’t raining hard enough to put on rain tires, but it wasn’t quite dry enough to safely race on slicks. (I’ve written before about why racing in the rain is hard.) But they managed to pull it off, put on a great show and @Brendan62 finally got that long-sought-after win. […]


Pocono: The Shifty Triangle

NASCAR engines like to run at about 8000-9500 rpm (revolutions per minute); however, the tires on the car rotate around 2400 rpm at 200 mph. The gearing in the transmission and the rear end gear reduce the rotational engine speed, with different gears providing different reductions. When you talk about the size of a gear, you’re actually talking about the relative sizes of a pair of gears. The gear on the left in the diagram has 20 teeth, while the gear on the right has 10 teeth, so this gear would be a 2:1, meaning that the smaller gear rotates twice every time the larger gear rotates once. […]

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Andy Randolph

Kansas Wrap Up: What Caused all the Engine Failures?

The defining characteristic of the Kansas race was the surprising number of engine problems. Many of those problems can be attributed to the change in rear gear from a 3.89 to a 4.00. At 190 mph at a track like Kansas, your wheels make 2270 revolutions per minute (rpm). If you watch the telemetry on the television broadcast, you know that the engine is rotating around 9500-9900 rpm. Since the engine is attached to the wheels, there has to be something to change the rotation rate between the engine and the gears. […]

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Edwards, Carl