Per the factory instructions, you're gonna go 2 to 3 MPH into 4L. A quick, slight grind is normal. Personally, I stop and shift from 4H to 4L with the trans in N.

 

Is English your first language? If not, I understand. I think it was made clear
there is no "force". You wouldn't jam it while your gassing it. see > http://en.wikipedia.org/wiki/Force Or maybe you didn't think before you spoke?

I shift my 90 into 4 high anytime I like, but, no not while I'm applying "FORCE" to the drive train. A handy feature too.

 

Low speeds, under 10. Though I don't own a Jeep anymore.

 

Ya that what I do to go into lo im afraid of tearing it up I meen as long as the front axle has lock dont see y you would need to be moving to engage 4L

 

Alright, this is my last post in this thread.

The general consensus on Pirate4x4 (no offense to Cherokee Forum, but that site makes this look like childs play) is when you want to engage while moving, put the Trans into Neutral, Engage, than shift back into drive. That is for 4 High. 4 Low, completely stopped either in Neutral or Drive.

I personally do not care what the manual says, my ex's RX-8's manual said to use 5W-20 Non-Synthetic only. If you are familiar with RX8 Club forums, 5W-20 has caused pre-mature failure in the rotary engines. Mazda recognized this as well, but you can still go buy a RX-8 and the manual still states 5W-20. Go back a year or two into my posts, Gee Oh Dee, DJB, a few others and myself used to "debunk" common myths almost everyday. Just think using common sense, if you're moving at that speed, your transfer case internals are being hit with an extreme amount of force, 0-XX in a matter of a second.

So you can take that advice as you'd like. Take care

 

They're not being hit with force. The two driveshafts are spinning at the same speed and a collar slides over the a coupler in the transfer case just like a good synchro slider.

This is not a myth that needs to be debunked. It is fact. I've used it since 1984 and dealt with hundreds of customers using it the way it was designed and backed up by those who designed it.

I understand there is debunking to be done and I've done a fair bit of it myself. This is not one of those areas.

I appreciate your input and see that you have worked to get quite an education in your career. Unfortunately, this is a case where fact and experience win out over education and conjecture.

 

Ive always gone into 4H on the fly, never over about 20mph though...never had a reason to be going that fast and need 4x4..if im going from 4H to 4L ill slow down to a crawl..or a stop go into Neutral then T-case to 4L and back to drive..reverse those steps to go back to 4H.

 

That's how it was designed to work.

 

Not trying to hijack the thread but what would keep an 89' from shifting out of 4H. Like I can shift into 2 wheel and sometimes it have to go between 2 wheel and 4H a few times to get the 4x4 light to go off.

 

Try tapping the gas and letting off as described in the above posted instructions.

And performing the adjustment lowrange2 is giving you.

 

This one time, at Jeep camp, I shifted from 2Hi to 4Hi while traveling 183.5mph.

Cruiser, I just read this entire thread to point out that there'd be no excessive force since both shafts are spinning at the same speed when you shift... but you beat me to it. Now, If you've swapped in an axle with manual locking hubs and they are unlocked it would be a completely different story.

You need to climb under and adjust your linkage. It's not difficult.

Here's how:

From the manual.

"SHIFT LINKAGE ADJUSTMENT
(1) Shift transfer case into 4L position. (make sure your shifter is fully in the 4L position)
(2) Raise vehicle.
(3) Loosen lock bolt on adjusting trunnion (Fig.
87).
(4) Be sure linkage rod slides freely in trunnion.
Clean rod and apply spray lube if necessary.
(5) Verify that transfer case range lever is fully
engaged in 4L position. (you can do this under the vehicle at the transfer case)
(6) Tighten adjusting trunnion lock bolt.
(7) Lower vehicle"

 

Correct, and thank you, Sir.

May I see your Certifications, please? LOL.



Shifting on the fly is nothing new and your comment about front locking hubs brought it to mind. On my old Nissan Patrol, FJ-40, 67 Bronco etc, I would leave the hubs engaged if I was anticipating the use of 4WD. Guess what? You can shift them on the fly that way from 2H and 4H and back again!!!

 

Anyway..Hows it goen? I don't have the diagram. I think you will find three vacuum lines there on the disco. When you select 4WD, a vacuum switch puts vacuum to one of those three to pull the sleeve over to connect the outer axle. When it has actually moved over and engaged, a port there is opened to apply vacuum to a switch for the light on the dash. When you put it back in 2WD, vacuum is applied to the 3 port to pull the sleeve back.

Hope that helps! That link Cruiser posted by Laredo seems to be a pretty sweet way to bypass that business, but Idk about the light there. I don't mind having mine working as designed, but I only use 4WD for a minute now and then...

 

Is your vacum line disconected or pinched cuz that could be the problem

 

The light is vacuum operated?