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Old 02-18-2015, 02:03 PM   #191
EAGLE5
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Garage
Regarding critical speed...
Assuming top speed of 143mph in 4th gear...
Driveshaft RPM = (MPH)(1056)(Differential Ratio) / (Tire Diameter)(Pi)(gear ratio)

So...
Driveshaft RPM = (143MPH)(1056)(4.1) / (24.1)(3.14159)(1.213)

619132.8/91.839042947 = 6741.5rpm at 143mph in 4th gear, everything stock. That means, at most, a stock car needs a drive shaft that can handle a bit over 6741.5rpm.

So what is the critical speed of the AL drive shaft? I don't know how long the tubing is. ~6700rpm+ is my best guess for 52".If it's 50", more like ~7250rpm.
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