Geared for Speed

RC Car Action - - PERFORMANCE TEST -

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.

When the pin­ion is nearly as big as the spur gear, you know some se­ri­ous ve­loc­ity is about to go down. This is the VXL’S “speed gear­ing,” a 35T pin­ion and 55T spur gear.

The VXL model gets the same mo­tor plate and 70T spur gear as the Ti­tan-pow­ered cars, but the pin­ion is a 29T—that’s an 8-tooth jump up from the brushed 4-Tec.

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