Grinding going between 4H and 4L

Background - 2001 XJ auto with the NP 231. Just completed an SYE install and at the same time replaced the transfer case chain. Took my front DS and moved it to the rear so I could drive it, then went to the JY to get a new DS for the front. I do know that it will need new u-joints soon, but is fine for now. I average about 250 miles a month, and just locally - no interstate runs further than about 3 miles.

Took it out yesterday to put it in 4L and drove around in circles to make sure things were working as they should. Seemed ok, but when I went back into 2wd I got a clunk when I started to accelerate. Went back into the grass and drove a few more circles and it went back into 2wd fine that time.

Today in the garage, I fired it up, put transmission into N to shift into 4H and 4L in order to fix the dash lights. I had swapped bulbs so I shifted to see if they would illuminate. Anyway, while the transmission was in N, I shifted from 4L into N then into 4H on the t-case and going into 4H, there was some major grinding as I shifted into 4H. Noticed that if I went really slow I could make it grind continuously. When I "slammed" it from N to 4H it grinded just as if I had to make a gear that was still mesh into a gear that was rotating.

Never noticed that kind of gear mesh grinding before I did the SYE install. Any ideas?

A cold transmission will rotate the output shaft pretty readily in neutral. Simply shut it off to shift it.

Digger87xj said:

A cold transmission will rotate the output shaft pretty readily in neutral. Simply shut it off to shift it.

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and also check to make sure the linkage is adjusted right.

Here's how the factory suggests you shift the transfer case and I've been doing this since these things were new and I worked at the dealership. Quoted from the owner's manual. The suggestions in CAPS are mine.

"To engage, shift the transfer case lever from 2H to 4H while the vehicle is moving at any legal speed". I LET OFF THE GAS, THROW THE LEVER, TAP THE GAS AND LET OFF.

4L position: " To engage, slow the vehicle to 2-3 MPH , shift the transmission to Neutral, then shift the transfer lever to the right and pull firmly rearward to 4L".

TO SHIFT OUT OF 4L, SHIFT THE TRANSMISSION INTO NEUTRAL WITH THE VEHICLE STOPPED, SHIFT THE TRANSFER CASE LEVER TO 2H, THEN THE TRANS TO D IF YOU HAVE AN AUTOMATIC, OR INTO FIRST GEAR WITH A MANUAL, AND CONTINUE ON.

Revised 11/20/2014

Digger87xj said:

A cold transmission will rotate the output shaft pretty readily in neutral. Simply shut it off to shift it.

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What he said.

As mentioned, even in neutral there can be enough drag in a cold transfer case to keep things spinning. As for the clunk coming out, I had a similar problem with my 99 and 95, which did not occur with the 87 and 93. I believe at some point partway through 1995, the NP231 internals were changed and the synchromesh was dropped. At that point, it seems, even a little drivetrain wrapup, such as you might get with differently worn tires, will cause a delay coming back out of 4WD and a clunk when it does. You can usually hasten the release by stopping and reversing.

Interesting i thought all 231s(command trac) and 242s (selec trac) were syncrod

Confirmation on this please for my own mental records?

Not sure about having synchros inside, but if the front and rear drive shafts are turning at the same speed as in driving, they will be...............

outlander said:

Interesting i thought all 231s(command trac) and 242s (selec trac) were syncrod

Confirmation on this please for my own mental records?

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not all are syncroed. early ones with CAD are. No CAD = no syncros.

Digger87xj said:

not all are syncroed. early ones with CAD are. No CAD = no syncros.

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Shifting between 2 high and 4 high usually is not a problem I do it at any speed before the wheels start slipping by simply letting off the gas move the lever then get back on the gas. Shifting past 'N' is the one that requires removing all power from the engine with the XJ going less than 5 mph before attempting to shift.
Personally, I go into 4 low with the AW4 in park only. Going out of 4 low is when I put the AW4 in 'N' with the XJ moving slowly.

Regarding the synchronizer, I think there is one on the gears somewhere in the front drive mechanism. I think I saw one when I replaced the OEM shaft with an SYE shaft.

techno1154 said:

Shifting between 2 high and 4 high usually is not a problem I do it at any speed before the wheels start slipping by simply letting off the gas move the lever then get back on the gas. Shifting past 'N' is the one that requires removing all power from the engine with the XJ going less than 5 mph before attempting to shift.
Personally, I go into 4 low with the AW4 in park only. Going out of 4 low is when I put the AW4 in 'N' with the XJ moving slowly.

Regarding the synchronizer, I think there is one on the gears somewhere in the front drive mechanism. I think I saw one when I replaced the OEM shaft with an SYE shaft.

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If you speak about the t-case in your '96 in your sig line, then no, there definitely are not any syncros in your t-case.