Grinding explanation

I have a 1995 K2500 8600 gvwr with a floor shift transfer case. My question isn't how to fix the grinding, its a transfer case - they grind. My question is how is it grinding?

Here is the situation. I have the truck at a dead stop in 4 Lo with the transmission in neutral. I shift the transfercase into neutral - no issues. With the truck still in neutral, and at a dead stop - the transfer case grinds like crazy shifting into 2 Hi (only a little grinding if you slam it hard).

I don't understand how it can be grinding - what is turning? The output shaft of the transfer case isn't spinning because it is locked to the stationary rear tires. This makes me think the output shaft of the transmission is turning - it has to be right? Isn't the point of neutral to decouple the output and input shafts in the transmission - why would the output shaft be turning? Am I missing something?

try park next time instead of neutral?

RichLo said:

try park next time instead of neutral?

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I always shift in park, that way the output of the trans is locked and not idling.

If there is no resistance to stop an automatic from spinning, then it'll grind when you shift.

Try doing it in park or with the truck off.

That's what I don't understand I guess, why does the output shaft of the transmission spin in neutral?

Because the engine is idling, the converter is spinning, fluid is transferring, and nothing is holding the output shaft.

It's just all drag of everything.

I turn the engine off,shift tc then fire it up,put trans in gear and go.Takes just a few seconds and no grinding.

Blazer Eagle said:

That's what I don't understand I guess, why does the output shaft of the transmission spin in neutral?

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Same reason a manual spins the wheels on a lift with the engine idling in neutral. Though not engaged, the stuff is still in contact enough to spin.