Autotrac ?

This is my first autotrac. '99 Z71. Why does the front drive shaft not spin freely when the truck is in 2 wheel drive? Or should it? My last two chevy's were '98 Z71 and '04 Duramax 4x4, both were not autotrac transfer cases and the front drive shaft would turn by hand in 2 wheel drive while under the truck and the truck on the ground!

Anyone?

With autotrac, the front driveshaft should spin only when you are driving......when you are in park, it shouldn't move, or only move about 1/4 inch either way......

Yeah, seems like to turn the driveshaft, you'd have to turn the front wheels/front diff.

Ok, just making sure. Cause the regular 4x4 trucks when the truck is in 2x4 the front drive shaft coming out of the diff will spin freely. Not so with this autotrac.

Ok, just checked the wifes '04 trailblazer with autotrac, and the front driveshaft will spin freely when in 2x4! I still think there is something wrong with my '99 silvy! I started to trouble shoot it when I discovered a "noise" "humming" when I put it in 4x4. So I checked the ujoints--ok, a little play at the transfer case rear output yoke when you push up and down, hence the "clunk" you get when dropping it in reverse. Everything seems to work ok, only got the "service 4x4" light once but it never came back.

Theres nothing wrong. Mine doesn't spin. IT only turns when in 4 wheel drive or when your in auto 4x4 (which i recommend not using)

I agree dont use autotrac if you pulling or out mudding its very hard and the transfer case clutch pack I would only use 2hi or 4hi.

the humming in 4 by 4 is normal.....don't worry man....

Uh mine doesnt hummmm

Well, just changed all the fluids to Syn. (including the new "blue" transfer case fluid) and truck still makes a "humming" in 4x4, but hey 4x4 still works, and I don't use it that much--if it breaks I'll fix it!