The way an open diff works is power is transmitted to the side with the least amount of traction via the spider gears. When your talking drag the process is reversed. The ring & pinion are stationery while the rotation transfers to the disconnected passenger side of the axle.

 

Thank you for taking the time to explain that. Definitely makes sense.

 

I'd like to add an example for you. When both tires of an open diff vehicle are off the ground, you spin one tire and the other side turns in the opposite direction while the drive shaft (and ring and pinion ) do not turn at all. The rotation transfers through the spider gears to the other side without affecting the ring and pinion.

 

Does this also work if the vehicle is in gear or just in neutral?

 

Either way. In park has the same effect. You should try it.

 

Lol as soon as this wind quits whipping that yall sent our way I think I will. I knew the tires spun different ways when I jacked it up but I honestly couldnt recall what the driveahaft did.

 

Oh I understand the whole locker keeping the drivers side engaged and the affects of it. Fyi having the front driveshaft live doesn't affect trimming radius. Mpg did take a small hit though. ( read Sig.) Just was unsure if the ls would be "tight" enough to affect the driveshaft in 2wd.

 

Ok. So much got mentioned I don't know who to respond to lol. I'll just add my two cents.

Assume for a second, that a limited slip acts as a locker in the front axles and is tight through the turns.(I know it's not 100% but bear with me for a sec). The wheels won't have too much drag offroad, but will have huge issues if driven on the road, even with the transfer case is disengaged.

This was an issue after WWII with military jeeps they wished to decommission for on-road use. This is why they added manual locking hubs(see pick below). When unlocked, the manual hub releases the front wheels from the drivetrain, allowing each wheel to spin freely. The transfer case then disengages the front driveshaft. At this point, the only mpg effects come from the weight of the added parts. You could have a blown differential in the front, and the car would still drive since the transfer case is released, and the front hubs aren't connected.

If I'm not mistaken, all 4x4 f-150s 9th gen and up have electronic locking hubs, which lock and unlock when the 4x4 switch is engaged. If this is the case, then having a limited slip or locker will have zero effect on mpgs while in 2wd. If for some reason these vehicles don't have them(maybe due to all factory models having open front diffs) I believe they make kits so you can add manual ones yourself.

 

Yeah, I may have been reaching on the turning radius. Lol. I had a front locker in an old Chevy 4x4 & it wouldn't turn for anything. The axle disconnect in the Ford makes a big difference there. But I could see possible vibration issues popping up because of the increase in rotating parts. I wouldn't mind running a locker in the front of a trail rig, but it's a bit pointless & overkill in a DD or mostly highway truck.

 

The hubs are not electronic. They are full time with no way of disconnecting from the axle. The axle itself uses a vacuum diaghram to disconnect the passenger side axle shaft from the differential. So your basically running 3wd with the transfer case powering only the rear wheels . You also have to consider the effects of the diff bearings being used more than necessary. But all in all, it will affect the mpgs regardless.