1990 XJ-Texas Edition

Alright y'all I could really use your help. I finally did the vac bypass for the d30 last week (after learning about it 7+ months ago) and discovered the t-case will not go into 4hi but will go into 4lo perfectly fine. I already tried searching for something similar but I couldn't find much, mostly about no 4lo. Is it possible for loose linkage to cause this or could it be more serious?

1990 XJ-Texas Edition

Oh also, no significant grinding while shifting, and I am doing it like the manual says to while moving forward slowly.

DFlintstone

That's weird. Mines the other way around. Not really because of the linkage, but (I think), because my mounts are shot any my whole engine/trans is an inch forward of where it belongs.

If you are getting it seated right on 4H, I got to wonder about that T-Case. I might check the fluid....(Dexron III ATF). Maybe drain it and check for metal, refill with fresh. Can't hurt!

I've never opened one up, only changed one once.

Vac bypass? You bypassed the vac switch on the T case? So it goes in 4H, but no 4 wheel?

This locks the disco engaged. https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/

Gee oh Dee

Its a 90, he probably bypassed the vacuum collar on the diff.

freegdr

Gotta climb under and look ....step 1 could be as simple as bad bushing on shifter linkage.

DFlintstone

IIRC it needs vacuum to stay engaged. If he just "bypassed" the switch on the T-Case, that would only prevent switch problems.

It can be "pinned" engaged. I don't mind having mine work as designed. It's trouble free since I put a loose zip-tie to keep every limb from knocking the vac lines off the disco.

Allot here would know better than me, but I think you need to go over/past 4H to get to 4L....

1990 XJ-Texas Edition

Yea that's the one I meant, I'm on the mobile app so its limited to what I can do but yea I did the cad bypass and fluid is fine nice and red

1990 XJ-Texas Edition

I have, but everything looks ok shifter doesn't feel loose but if it was it wouldn't go into 4lo would it?

cruiser54

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.

"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, and then 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".

Gee oh Dee

I see no issue bypassing the cad and locking it in. They gave up using that style because, with our hubs and transfer case, its just not necessary.

More moving parts, more stuff to have break or go wrong.

I like simplicity, less to be concerned about.

1990 XJ-Texas Edition

That's how I've been doin it same results no moving forward or back until I ho to 4lo
I'm with ya there the less stuff to break, the better.

cruiser54

"Noggin pokin'" is in order now. Poke your noggin under the Jeep and inspect the transfer case linkage and bushings.

1990 XJ-Texas Edition

Already have all seems to be ok, there isn't any excessive play (from what I can tell), is there a possibility of something loose inside making this happen?

DFlintstone

I wonder if A PO just left it in 4H if it could have dusted a gear in the TC. If the selector moves it there, the disco is locked/clipped in, and everything but that works, Idk. Gotta wonder. I might drain it and look for metal.

Then 4H IS next to neutral.....No harm at looking at the engine mounts. Centered? If the Jeep were rear ended the engine could be rearward, putting that TC linkage toward Neutral. (I broke my mounts and the engine is forward from snapping a chain too hard pulling a log). Low is on the edge of the throw now.

freegdr

Im sure you've tried adjusting it ?