re: flat towing a Jeep YJ

quote:

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why is that, from a mechanical standpoint?

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The input shaft to the tranmission is not spinning. That input shaft from the engine lubes the tranmission.

The fluid coupling from the transfercase will spin the transfercase input shaft (output of transmission) even though the transmission is in neutral. If the transmission is in neutral nothing is lubricating the output shaft of the transmission and it can sieze up like our buddy in the CJ.

In gear, the tranmission locks that output shaft and the fluid coupling from the tcase can't spin it. So, its a lubrication issue but the opposite of what I thought. You want to lock the transmission and let the tcase spin free (the tcase oil pump is on the ouput shaft where the driveshaft attaches so it will spin with the spinning driveshaft).

Edited for sucking at typing.