Can anyone explain to me how the automatic hubs work on a 2003 chevy 4x4.
It looks to me like its not actually the hub that locks, but rather something inside the front differential.

Or does someone have a link or visual aid to help explain this?

 

your right, your truck (and most newer trucks) do not use locking hubs anymore. Your also right on #2, there is a locking mechanism in the front diff. Magnify the schematic below, components 9-16 are collars and shafts, almost like a synchro on a manual trans, the fork joins the 2 axle shafts via some sort of motor/actuator.

 

So in all reality, a guy with a 4wd pickup who is running in 2wd down the road still has a ton of rotational mass thats robbing power?

 

Yes. Even though the front isn't ingaged, the truck has to "push" the frontend drive components. The front half shafts and stuff still turn. Just jack up the fronend and rotate one front tire. The shaft will turn. Not to mention the transfer case.

James

 

Ok. Here's what i'm wondering. If i launch the truck in 4wd and then kick it to 2wd, will it come out of gear:

1. In the transfer case and not the front diffential.
2. In the transfer case and eventually the front diffential. or
3. None of them because its under a load.

BTW, I have a manual floor shifter type transfer case.