How the Jeep Wrangler 4x4 Works

This is an instructional video on the jeep wrangler on its traction with 4x4 wheel drive

https://www.youtube.com/watch?feature=player_detailpage&v=G9AbWnRQCac

Note that they say noises can be expected when shifting in to 4 low.
But the way that they are saying to do it kinda makes it grind .
Doesn't grind on mine but i never put the transfer case in neutral, I go from 4 hi to 4 low  or vice versa, in one continuous motion while jeep is basically stopped.
I guess some do and some don't.

The way described in the video is how i have to do it (automatic) while going about 5 mph throw the transmission into N then when rolling at about 1-3 mph the transfer case lever will go down past N into 4lo otherwise if the tranny is not in N it will not engage 4lo.

That is the way they are saying to do it on your model. mine is a TJ 5 speed, maybe that's why, i don't know.
Does yours grind at all?
I can have trans in any gear as long as the clutch is in and shift into 4x4 low without moving or grinding,, hmmm,,

My YJ is the same way Mark, no grind with the clutch in regardless of the gear as long as it's not moving. My XJ with the auto though does grind a bit, regardless of slowly moving or completely stopped. One of life's great mysteries.

i guess that by having the clutch in you have essentially disengaged (put it in neutral) so you can shift the transfer case freely.

my jk will grid a tiny bit rarely only if i'm going too slow,up hill(way harder since i have to try an be as fast as possible to not roll backwards) or stopped .

WTF was BLD available on? Lemme guess, Rubicon only?

That's a pretty neat idea, though. I never thought of that. Although, you can DIY, it just takes more practice. If it happened automatically, I wouldn't even be mad.

Rob Cote wrote:WTF was BLD available on? Lemme guess, Rubicon only?

That's a pretty neat idea, though. I never thought of that. Although, you can DIY, it just takes more practice. If it happened automatically, I wouldn't even be mad.

All jk's come with BLD its part of the Traction control as all the hardware is already there (brakes). It was just a matter of telling the computer 'apply the brakes' rather than reduce throttle to limit tire spin. TCS can be disabled but BLD stays active since its purpose is to allow more torque and limit the slipping tire to spin as fast as the working tire.
All in all a very handy system.

Says that you can put it in 4 hi at speeds up to 55 mph, i have put mine in 4 hi at 80 mph with no problem at all.

Regarding the lo-range discussion, I have a 5 speed and if I'm not at a full stop shifting into 4LO, it will grind. I'm pretty sure I don't have to be in neutral, though, as long as the clutch is depressed.

When you shift from 2HI to 4HI, I believe you're just engaging a clutch in the transfer case. This is why it can be done at speed. However, when you shift from 4HI to 4LO, you have to shift to a new gear (that's where the reduction happens) and there is no synchro on this gear set as far as I know. My guess is that's why they recommend moving at a very slow crawl (this helps the gears move a bit relative so they can engage easier). Whenever I try to do it at anything other than a full stop, it sounds horrifying.

That's how my YJ is, if you try to engage 4Lo while not completely stopped it sounds like the case just blew up. It's a gnarly sound, and part of the reason why it takes me so long to shift on trail rides...that and the YJ 231 requires you to go down, then to the right, and then down once again to get into 4Lo, and that shift handle is one tough mother to move. The straight line pattern like in my XJ and in TJs (and I'm sure others) is definitely much quicker and easier to do.

Rob Cote wrote:

When you shift from 2HI to 4HI, I believe you're just engaging a clutch in the transfer case. .

The transfer Case does not have a clutch.

Then what connects the front drive to the rear drive that allows you to engage on the fly?

All i can say is that it's not a clutch.

Perhaps it uses a synchro-like component to engage the mode hub/sprocket? Or it's f'n black magic. I'm really not sure. Anyway, I misspoke. I didn't mean clutch in the traditional sense. I just used it as a word to convey that the transfer case is simply engaging a gear with an already spinning shaft, whereas when you shift to 4LO, you're selecting an altogether different final drive gear. And THAT'S why you have to be stopped (or nearly stopped).

There is no clutch as mentioned. What they do have is synchronizer hub, sleeve, and stop ring. Same idea as the manual transmissions with synchro gears. A good example it the T-18 tranny that does not have a 1st gear synchro, you have to come to a complete stop to engage 1st gear, 2 thru 4 have synchro gears and slide in on the move.