Jeepification

This could be true. This past winter, 4wd worked great both high and low. We had a rainy day a few weeks back and I decided to try 4wd. Going roughly 8mph, I pulled the lever and normally the 4wd light comes on, but it didn't this time and shortly after, maybe 300 yards later a loud buzzing sound happens and winds down as I slow down. Beyond this, it was hard to disengage the 4wd lever until I was stopped completely.

Now, I can pull the lever and nothing happens, no light, no 4wd tug, nothing. It does seem like 4wd low works. I still don't get a 4wd light but the gear ratios clearly change and the jeep feels like a tractor. Feels like it's definitely in 4wd low.

I had a shop look at it the linkage and they said it was "butter smooth" and moving perfectly. That the defect is internal to the TC.

Now, I searched these forums and got nowhere. The search gives lots and lots of results that are less than useful.

That said, I'm not sure where to go with this one and would like some current ideas on the topic.

I usually upgrade if I have to replace. Is Atlas my only real option there? Is there a trusted place that does beefed up 231s I can buy as an assembly?

I do not have the luxury of the actual work taking more that two days. No shop will guarantee me that or mess with a TC they didn't supply for that matter. So, it's going to be on my back in my driveway. A bolt in assembly is required.

Thanks in advance for chiming in on this probably beat to death topic.

GreaseMonkey17

There's a good TC for your Jeep on my local craigslist
for 90 dollars . I'd buy a good used one bolt it in and call it a day if you verify it is in fact bad .

Guywitha92

You have the 231 in now?

andrewmp6

You can buy a upgraded np231 here http://www.jbconversions.com/index2.php?pc=1 by upgraded i mean rebuilt with the wider chain upgrade and the 6 planetary gear set and two sye options short and long.Its 1500 plus shipping but its cheaper then a Atlas which will run you 3k easy.If your a hardcore off roader id say get the Atlas but if not that upgraded np231 should be your best option.

Guywitha92

There is a guy near me that heavy duty builds them and he wants like $800. He may ship.

bad_idea

I'm not convinced your TC is bad. Could be the linkage is out of adjustment. Does the TC have fluid in it? I'd suggest you put the jeep on stands and run it through the gears. Watch the linkage from below while someone operates the shifter from above.

sycoglitch

What's your year and drivetrain and what has been the procedure you've been trying to shift since the first rain storm. Did it don't the TC to see the fluid level. The 231 is a shift on the fly part time case. At any normal highway speed, all you need to do is release the accelerator and pull the lever to 4hi. Same procedure to go back to 2hi. when you're in 4hi, do you feel binding as you slowly turn the steering wheel, don't go crazy here so you don't wreck anything since you need slippage to safely run the 231 without damaging anything

XJlimitedx99

I think I'm in the same boat as you, OP. This past winter I used 4hi pretty frequently in the snow. One time I pulled it down into 4wd while traveling ~15mph and it ground the gears bad and spit itself into neutral. Like that buzzing sound you mentioned. My 4hi has continued to do this every time I've tried it since.

That sound is most likely the gears of the t-case's main shaft and the 4hi gear skipping over the tops of each other, grinding the tops of the teeth off. Our situations differ slightly because I have the Boostwerks linkage.

Like somebody mentioned before, the linkage could have been tweaked slightly which could cause the 4hi gear to not be engaging fully. In my case, I think my linkage is slightly too long so when I engage 4hi the shift level is bottoming out on the bezel but the case is not being fully shifted. This could be caused by the body flexing just enough to move things around a bit, or maybe the drivetrain took a good jolt at some point to throw things off, etc, etc.

my suggestion to you is to remove the linkage from the case and manually shift it into 4hi then try to drive it (on a slick surface). Then you'll know if its the linkage or the case.

If it is the case, just pick up a cheap used 231. They're everywhere and easy to swap.

cruiser54

First:

Check the fluid level along with trans mount and engine mounts.

Second, do this:


Third, shift like this:

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

5-Speed

I had no idea it was ok to shift into 4H while moving. I always come to a complete stop then throw it in. Good info to know but will most likely stick to what I am used to.

cruiser54

Then plan on it being a ***** to shift........

5-Speed

Never has been an issue. Always butter smooth. In gear with the clutch in or just sitting in neutral seems to be the same. Goes right in to 4H and 4L. Pops out just fine too.

I did the same in my last XJ (98 5-speed) and both my dads TJ and YJ (both 5-speeds). Never had any issues.

4.3L XJ

I agree, do some checking into the current tcase. First of all, what year Jeep. If it has a vacuum disconnect, the lack of light may be a vacuum problem since that is what activates the light and has nothing to do with the tcase. If newer, the lack of light might only be the switch on the tcase. Make sure it engages by checking with one front wheel jacked up slightly. If it spins when 4WD then it is not engaging.

Jeepification

Pretty sure that's what came stock in my 2001.

Def has fluid. I'm looking for jack stands that are tall enough to do this.

I'm aware how to shift the jeep. There is none of the usual binding when in 4 hi but there is in 4 lo. It's a 2001 with a mild lift and 31s. Tc drop installed.