Quote:
Originally Posted by LostMy65
I really think there has to be "Standard" lengths for drivelines. The Bell housing was mounted in the same place for thousands of trucks. After that you only have to consider what transmission you have, then short or long bed.
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Nope. Too many other variables.
The operative concept here is to control the driveshaft "critical speed", the point at which it begins to swing like a jump rope. It is affected by length, outside diameter, thickness, material, mass and rpm. Highest shaft rpm is affected by vehicle top speed, rear axle ratio and tire diameter. Length is affected by wheelbase and driveline configuration.
The driveline is also affected by any unusual or unpredicted system resonances, which can destroy a driveline even at a speed lower than the critical rpm.
From an OE perspective the driveshaft choice (one piece vs two piece) can be manipulated by controlling any one or more of those variables.
Hence there's a little more going on than picking a length and slapping a couple yokes on it (from a production standpoint).
There is a chart that the engineer keeps (like the brake system release charts I have posted in the past) that shows all of the driveline configurations and shaft lengths for every GM light duty truck. I have asked the engineer for it on a couple of occasions but he has not come through with it.
K