You could try that but once you get it spinning, there would be no way to stop it. You would most likely damage something if it was freewheeling and you changed reverse to drive or, god forbid, park. That a lot of rotating mass. The only way to do that would be to shut off the engine in gear and wait 'til it stops turning. Even then, I would be concerned about overspeeding something expensive.
Definately a unique idea. I don't see why you couldn't do it. Put the TC into neutral, shift the truck to drive, let it idle for 10 minutes and see if it makes any heat. When you are ready to go simply shift the trans to neutral, wait say 30 seconds to be safe for the output shaft to slow down, then shift the TC back to 2wd and go. Don't pull back at all on the shifter so you cannot accidentaly hit reverse or park.
I know that many vehicles still transmit some power even while the trans is in neutral due to the fluid between clutches transfering some power like a torque converter, but I don't see it as much of an issue. The output shaft and connected drums shouldn't represent all that much inertia.
You have to remember that in the Auto's you are moving fluid the moment the motor starts turning over. Also, in our allys you are spinning at least the C1/C2 housing and TC. I have noticed that the tranny will warm up nicely just sitting their idleing in park.
Also, good luck breaking the park prawl. That thing is huge and rated to hold 26,000lbs GVWR.
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