Truck is a 94 f250 4x4 auto...What is the correct way to shift in and out of 4 wheel drive??

 

You can shift on the fly(when moving) from 2hi to 4hi but you want to be moving in a straight line with no wheel spin, and obviously you don't want to use 4wd on clear pavement or other hard packed surfaces unless you're only going to be moving straight forward or back to pull out someone3 that is stuck for example. Offroad and on snow covered or lose surfaces you can drive normally but avoid turning the wheels to full lock as some U-joint binging will occur.
This assumes you have automatic locking hubs, if you have manual hubs they have to be locked in before shifting the t-case. It's also OK to drive around with manual hubs locked and the t-case in 2wd but this will hurt gas milage as the whole front driveline is now turning.

 

OK...Thanks for your info...I forgot to say it's got auto locking hubs...But-what about from 4HI to 4LO???

 

You should come to a stop and shift the trans into neutral before changing between 4-high and 4-low. If you have the electrontic shift t.case it won't let you make that shift unless you are in neutral.

 

You cannot shift on the fly from 2hi to 4hi unless the hubs are locked, whether auto or manual hubs. With auto hubs, if you stop and shift to 4hi, then start driving, you can shift to 2hi and the hubs will stay locked until you change direction (drive to reverse). Then you can shift on the fly back to 4hi.

 

Not strictly true, but not a bad guideline never-the-less.

Of course it would be pointless to shift into 4-High with unlocked manual hubs, so we won't worry about that. Just don't do it.

But if auto hubs are unlocked at least the electronic shift t.case in my '95 F-150 could be shifted from 2-High to 4-High on the fly. That t.case has a magnetic clutch in it that pulled the front driveline up to speed before it engaged the gears. The owners manual said you could do that up to 50 mph. It made a heck of a bang when doing it, so I didn't feel like it was something I wanted to do much, but the owners manual said it was OK.

Note that I do not know if a lever-shift t.case can be shifted on the fly with unlocked auto hubs. I suspect that it should not be, but that's just a guess.


I might just be reading you wrong here, but what I see is you are saying that it's only OK to shift from 2-High to 4-High with auto hubs after you have unlocked the hubs by backing up in 2WD. That would be the same as shifting to 4-High before locking the hubs in which, as I pointed out, is allowed (at least with the electronic shift t.cases), but doesn't sound that good on the t.case. What I think you were meaning to say is that if you are driving in 4WD and shift to 2WD auto hubs will stay locked. So as long as you don't stop and back up you can shift back into 4WD. If everyone else understood that correctly I'm sorry for not reading it well.

 

i have never seen a manual t-case with auto hubs.

 

With manual hubs, you have to lock them in before you can shift between 2H and 4H when moving. With auto hubs, the first time you go to 4H while moving, they will lock up and stay there til you go back to 2H and drive several feet in the direction opposite that which you were moving when they locked up. Yes you CAN shift into 4H with auto hubs while moving, there is a magnetic clutch that spins up the front driveline to engage the hubs before the actual transfer case shift is commanded.

With either auto or manual hubs, you CANNOT go from either of the high ranges (2H or 4H) to 4L while moving, you're supposed to stop and put the trans in neutral to do this but with a manual transfer case it's actually easier to put the trans in neutral while you're rolling about 1-2 MPH and then make the shift... it helps the planetary reduction gear mesh up easier when going between low/high.

 

Me either, but I figure if I left that out the first reply would be from someone saying "but wait, the manual shift t.cases can't be shifted until the hubs are locked"

 

I have THREE! My 89 f250, my 94 F250, and my 90 F150. All Auto-Locks from the factory.

 

Yeah we had a 94 f250 with manual shift lever and auto hubs.

 

Mine started life with auto hubs and has the manual shift transfer case.

 

My '90 F150 XLT Lariat has a manual transfer and had (until I swapped them) automatic hubs. I guess it's possible that somebody swapped them to automatics earlier, but everything else in the truck, except rims and tires, is stock.

 

Thanks to everyone for all their help...This is the BEST forum!

 

I assumed the OP has a manual shift T-case, being an F250. I think the electric T-case was only on Broncos & F150s, but I could be wrong...


I was meaning that the hubs must be locked to shift on the fly, though I see I phrased it kinda ambiguously. Sorry for the confusion.