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Originally Posted by Gregski
I hear ya, here's an actual photo of the General's process for determining which truck gets which driveshaft:
hope this helps,
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I've been expecting this post.
My response:
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It has to do with propshaft (aka "driveshaft") critical speed.
Propshaft critical speed not just based on wheelbase but is also based on trans type (length), rear axle ratio, tire size, and engine type (larger engines allowing a higher top speed) AND/OR any strange resonances in that particular combination (camping out on that resonance will break the trans/transfer case tailshaft housing).
So - a long wheelbase truck with a low (numerical) rear axle ratio spins the shaft slower and might get a one piece, but an otherwise comparable truck with a high rear axle ratio might get a two piece.
One other comment - critical speed is not directly related to balance, but rigidity. When the shaft exceeds it's critical speed it begins to bow in the middle and swing like a jump rope. Hence the disturbance and durability concerns.
You can get around it by going to a larger diameter steel tube - or more expensive alternative materials like aluminum, carbon fiber, an aluminum/carbon wrap, or exotic materials like "metal matrix" (aluminum impregnated with other metals).
So - given two otherwise identical appearing trucks - there could be a tire difference that put it over the edge, or perhaps a different horsepower rating which would allow for a higher top speed, or some unseen bending resonance that shows itself during testing.
K
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So - not only could we manipulate one pc vs two pc based on material selection, but the program team might even speed limit a vehicle (via pulling fuel or ignition) to limit top speed to allow a one piece configuration.
K