Shifting in and out of 4WD

On Wranglers and most newer GM 1/2 ton trucks, even Ford 1/2 ton there are no lockable hubs but instead there's a spline shaft inside the differential tube that is actuated by the engagement of 4x4. In these systems, there are parts that spin full time and parts that don't. It gets a bit more complicated on what is and isn't spinning.
Fantastic explanation!

Quick note on F-150's. F-150's do have vacuum actuated locking hubs, though they are locked by default. The vacuum unlocks the hubs when in 2WD. This also means the hubs are fail-safe - if the vacuum system fails the hubs will be locked, allowing 4WD to still work.
 
I shift mine on the fly even at 65MPH. As long as tires are inflated properly, and tires are matching with tread within 2/32" and you aren't spinning out or under heavy throttle it's not an issue. even on my 1979 F-250 with hubs locked I can shift in and out of 4H at 55mph. These vehicles are designed for it, no reason to over complicate things.
 
Wrangler system:
2011-06-03_021917_4xvac2.jpg
The thing that you show as "Wrangler system:" is called a Center Axle Disconnect or CAD. It is common an GM and Dodge/Ram trucks, but I don't think on Fords. My 2016 Jeep Wrangler Rubicon does not have this at all. The hubs in that Wrangler are not unlock-able at all. In effect it is just like leaving our Super Duty hubs in the lock position all of the time. Jeep determined that it was not a big deal to leave the front axle spinning all of the time. With manual locking hubs in snow country it has forever been quite common to leave them locked in all winter long. Slight reduction in fuel economy and slight increase in wear, but no big deal.

The Tremor front axle is somewhat unusual in that it is a limited slip differential. Most 4wd front axles are simple open differentials. Limited slip differentials can wear out so it might be a little more important to unlock the hubs. Probably not a big deal though because think of it this way: There are many many vehicles out there with Limited slip differentials in the rear axle that run their whole life engaged.

And BTW, a Center Axle Disconnect would not really make sense with a limited slip differential because one side would still be spinning the ring gear at all times. A CAD works by letting the spider gears spin and the ring gear can be stationary.
 
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Just curious how you guys shift in and out of 4wd. On all my trucks i have no problem shifting into 4wd “on the fly” but usually try and keep the speed fairly slow (maybe 20-25mph max). When I shift out of 4wd back into 2wd I almost always try to come to a complete stop but sometimes that isn’t a viable option so I slow down as slow as I can. I’m talking strictly about 4wd HIGH.

So, do you all have any rules of thumb you like to do when shifting into 4wd? Or do you just shift in and out whenever you want and do t care about the speed you are driving?
The dash on my 23 tells me to take my foot off the gas to perform the 2wd to 4wd shift i beleive.
Always have to stop for 4 low.
With the tremor as soon as you pick slippery road if your driving its going to put the truck in 4wd.
I always try to stay under 40 or so when going to 4wd. My 2006 gmc would hit pretty hard while moving when going into 4wd. The ford seems smoother.

Hope this helps
 
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