I believe the big difference is with the full time on, any 'one' of 4
tires can be the main drive wheel, so when stopped and not using the
brakes to vary the load, only one tire can be merrily spinning away.

If you put it into 'part time', the front and rear axles are locked so
when stopped on ice at least 'two' wheels are spinning merrily away.

When this happens, you can hit the brake pedal and with some practice
get both rear wheels spinning and sometimes even all 4 will break loose.

Torque goes to 'both' tires on one differential equally, so the one tire
spinning loose has very little torque on it so the other side sits
still. Hit the brakes or my owners manuals say you can use the
emergency brake and you apply braking torque to the spinning wheel.
This can get strong enough to match the traction of the stopped wheel so
that the wheel on the other side will break loose and spin too.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Patrick wrote:
>
> Last night got a bit stuck in a big snow bank, Selectrac I6 4x4, i was on
> full time
>
> The rear right (passenger) wheels was spinning and it feel it was the only
> wheel really trying to get out, i know the 4x4 is working (Light on and
> feeling while doing u-turn ) but why i did not see the front wheel spinning
> while the gc was on Reverse , I was outside with the truck engage looking at
> the truck spinning. !!!!!
>
> I tried part time and no much luck. Got out of there with time and patience
> REVERSE,DRIVE,REV... Is AWD subaru vehicules working the same ?
>
> thanks
>
> Pat