I would be willing to bet a 4mpg drop running 4x4 all the time. That's 100 miles less per tank of fuel. If it's a daily driver that would be asinine. Strictly off-road I could see it. It's actually the same reason I will never put mud terrains on my daily ever again. The grip is great and they look awesome but the noise drive me up the wall on long road trips.

 

It would only lock while the truck is turning I would think

 

Yeh im not an expert on the torsen but collin ran a spartan locker or lincoln locked up front. Those are full lock all the time in a straight line, in the spartans case.

 

Ya I could be wrong but that would be my semi-educated guess lol. Where's Jbrew when you need him?

 

Lol I have a how to and drawback post by collin somewhere I need to dig up.

 

don't forget there's a transfer case... when you have your truck in 2wd it isn't going to receive power to the front differential, thus meaning that it won't be engaged.

is this the case or am I missing something??

 

Constant 4x4 on hard surfaces is usually hard on the front drive shaft first then it sort of tears the crap out of the drive line. Some are designed with a mini differential in the transfer case to help with the torsion wrap up between the two axles but it is still hard on the front drive shaft and you get perty regular destruction of it joints.
Best not to worry about gas mileage and just get out of 4x4 if you don't have to have it.

 

How is that any different than the rear driveshaft?

and I thought these trucks weren't full time 4x4? I thought they have a part time transfer case.

 

Its not so much that it gets power but that it causes drag. When out of 4x4 the passenger side axle shaft is disengaged via sliding collar. This means that only the driver side is connected to the front ring and pinion.

 

This is what I was getting at! Just forgot how it actually worked. My thinking was that if its not completely open in the front you will technically not be able to disengage 4x4.