Geared for Speed
All 4-Tec models roll out of the box geared for all-around action, and get an extra gear ratio in the accessory bag just for goin’ fast. The difference in ratios between the brushed and brushless cars, and between the stock and “speed” gears, is pretty interesting. Check it out: The VXL’S “speed ratio” is twice as tall as the brushed car’s stock ratio—that’s a big gear. If we factor in the 4-Tec’s 2.85:1 drivetrain ratio and 68mm tire diameter (I’ll spare you the math), we get a “rollout” of 48mm. That means for every revolution of the Velineon 3500 motor, the 4-Tec VXL (with speed gearing) covers a tick less than two inches. At the motor’s peak speed of 50,000rpm, that works out to 1.5 miles per minute, or 90mph! That doesn’t account for drivetrain friction, rolling resistance, and aerodynamic drag, however—that’s how 20-ish mph gets scraped off for a final top speed of 70+mph.