Odd Behavior After Transmission and Transfer Case Rebuild

Stinkbug

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I took my Jeep in to have the transmission 32rh rebuilt and the NP231 transfer case serviced (chain, pump, seals etc). I got it back a few months ago but it pretty much went into storage waiting for the time to take it out to play.

I have the opportunity to run a trail Saturday. This got me out to the garage to start loading up the Jeep and tiding up a few unfinished projects. It dawned on me that I have not run the transfer case through it paces to are sure it shifts in and out of 4wd properly.

Here is what I found:

  1. When the Jeep is in neutral, and you apply the gas it drives slowly forward. Not rolls. It moves very slowly under power.
  2. Shifting from 2h to 4h works as expected (drive slow firm yank on the shifter) in 8/10 times
  3. Can’t get it to shift to 4 low ( rolling very slowly with trans in neutral). Pulling the transfer case lever just hits a wall and won’t shift. It does t bring, the lever just won’t move.
  4. Sometimes with the engine off and the transmission in park, I can shift from 2h all the way through to 4 low like butter but not predictable.
I have a Novak cable shifter and prior to the service, it worked very well. It’s hard to imagine that the shop would have fiddled with the cable length for the job they did. Hopefully, I just need to adjust the cable.

I will likely take it back to they shop since I have to work every day before the upcoming trip but I am curious what you guys think might be going on
 
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Crawling forward in neutral could be a clutch clearance problem. Or something else, what do I even know? I did learn a few surprising (to me, anyway) things about the internals from when I rebuilt my 32RH that may help here. I was mega paranoid when I put it all back in, which included test firing everything w/o the driveshafts in. How surprised was I when I saw that rear yoke spinning like crazy even when I was in N!?!? Turns out that in N, none of the clutches or bands are applied, but the input section still spins. Apparently there is enough fluid coupling to make the output section also spin. Normally you have the driveshaft connected to the rear axle, which provides enough resistance to overcome this phantom output torque. But without the driveshaft it'll spin quite fast (probably more or less at the RPM of the engine, just a guess).

This is the speculation section, take it for what it's worth:

I said none of the clutches are applied so you just have fluid coupling. However, if for some reason those clutches were close enough together to actually bind together even when not applied, you might end up with enough "phantom output torque" from those clutches above and beyond that fluid coupling to slightly drive the rear wheels. When you replace the clutches there is a minimum clearance that must be met. If the clearance is insufficient, the builder needs to replace the pressure plate with a thinner one to increase the clearance. I'm an amateur hack and I checked, so I would presume that a qualified shop would also check. But everyone everywhere is fallible, so it's conceivable they didn't, or did and thought it was close enough to send, or who knows what.

Take that for exactly what it's worth, which is nothing. I could be completely wrong. But it also doesn't matter, I would take it back to the shop and make them fix it. Hopefully they won't give you grief for it having sat for several months. Shops will do anything to weasel out of warranty work.
 
I took my Jeep in to have the transmission 32rh rebuilt and the NP231 transfer case serviced (chain, pump, seals etc). I got it back a few months ago but it pretty much went into storage waiting for the time to take it out to play.

I have the opportunity to run a trail Saturday. This got me out to the garage to start loading up the Jeep and tiding up a few unfinished projects. It dawned on me that I have not run the transfer case through it paces to are sure it shifts in and out of 4wd properly.

Here is what I found:

  1. When the Jeep is in neutral, and you apply the gas it drives slowly forward. Not rolls. It moves very slowly under power.
  2. Shifting from 2h to 4h works as expected (drive slow firm yank on the shifter) in 8/10 times
  3. Can’t get it to shift to 4 low ( rolling very slowly with trans in neutral). Pulling the transfer case lever just hits a wall and won’t shift. It does t bring, the lever just won’t move.

I've never been into an automatic before but with it driving itself in N, it's likely spinning pretty good without a load connected (t-case in neutral), and a spinning transmission output as @hear described is not what the t-case wants to shift into a range. Is it getting into neutral and not all the way to 4L, or is it just not coming out of 4H at all?

  1. Sometimes with the engine off and the transmission in park, I can shift from 2h all the way through to 4 low like butter but not predictable.

This is normal behavior, it just depends on whether the teeth just happened to align when it all came to a stop. The fact that it does get into 4 low though, would imply the linkage mechanism is ok.
 
I've never been into an automatic before but with it driving itself in N, it's likely spinning pretty good without a load connected (t-case in neutral), and a spinning transmission output as @hear described is not what the t-case wants to shift into a range. Is it getting into neutral and not all the way to 4L, or is it just not coming out of 4H at all?



This is normal behavior, it just depends on whether the teeth just happened to align when it all came to a stop. The fact that it does get into 4 low though, would imply the linkage mechanism is ok.

It won’t even make it to neutral. Just back and forth between 2h and 4h is working as expected about 80% of the time.
 
I'd adjust the cable shifter. Betcha that's the problem.

If not mine had issues shifting into 4 low and it was because I was having issues seating the internal oil pump.

-Mac
 
I suspect the mode ring is on backwards.

would the below be true with a backward mode ring? I know it's an easy mistake to make but I haven't played with one recently enough to know what the results are.

  1. Sometimes with the engine off and the transmission in park, I can shift from 2h all the way through to 4 low like butter but not predictable.

It won’t even make it to neutral. Just back and forth between 2h and 4h is working as expected about 80% of the time.

in all candor, this could be reaching a little here but i wonder if being under load (from the transmission wanting to spin in N) is keeping the range hub from sliding out of High. I'm almost certain based on what you're describing from your transmission is that if you can get the t-case into N, it will bark at you like a rabid dog if you try to get it back into low OR high.
 
I suspect the mode ring is on backwards.

That's the ring that sits in the shifter fork? DIdn't know what that was called, but it is very easy to put that in the wrong way. I wondered what would happen if you did it wrong. There's a longer side and a shorter side...for the record, which way is it supposed to go?
 
That's the ring that sits in the shifter fork? DIdn't know what that was called, but it is very easy to put that in the wrong way. I wondered what would happen if you did it wrong. There's a longer side and a shorter side...for the record, which way is it supposed to go?
If you get it backwards, you don't get all the modes and it won't go into each mode correctly. There is a long and a short side past the shift fork groove. I seem to have misplaced my picture but I'll dig one up that shows how it goes.
 
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If you get it backwards, you don't get all the modes and it won't go into each mode correctly. There is a long and a short side past the shift fork groove. I seem to have misplaced my picture but I'll dig one up that shows how it goes.

Thanks, that would be great. Last time I cracked open a t-case I couldn't remember how it went. I had to scrub through the bleepinjeep SYE video and see if I could tell how it went. And of course I don't remember what I decided.
 
If you get it backwards, you don't get all the modes and it won't go into each mode correctly. There is a long and a short side past the shift fork groove. I seem to have misplaced my picture but I'll dig one up that shows how it goes.

I hope it is that simple of a fix and they can get it back together before my trip on Saturday.

BTW when I installed the SYE years ago I made the same mistake and Blaine identified it - fingers crossed he is right again.
 
Here's my mode ring, with the groove going down into the TC first:

Mode_ring.jpg
 
So here is what I have heard from the shop now that they have had a chance to look at it:

Regarding driving forward in neutral - They are going to adjust one of the clutches (maybe the wrong term?) to fix that. They said there is trouble with the shift cable. Says the plastic fitting that connects it to the transmission is worn. It is a discontinued part. He is searching for one but I don’t feel it is a high priority for him so I have one inbound from eBay.

When it comes to the transfer case not shifting it to neutral or 4 low. He says some transfer cases are just that way and you have to stop, turn off the engine, and put it in park before shifting but a higher quality fluid might help. We all know that is BS. I have been shifting that transfer case in and out of 4low for a decade and a half. I suggested to the mode ring to him but he poopoo’ that as a possibility. It was almost as if he could not fathom making such a mistake. He and I are going to have a bit more of a discussion about what’s the proper course of action. After all, it was I fine working condition when I took it to him just a bunch of leaks and maybe a stretched chain, now it simply doesn’t function.

Unfortunately, I believe I am headed for the infinite run around.
 
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So here is what I have heard from the shop now that they have had a chance to look at it:

Regarding driving forward in neutral - They are going to adjust one of the clutches (maybe the wrong term?) to fix that. They said there is trouble with the shift cable. Says the plastic fitting that connects it to the transmission is worn. It is a discontinued part. He is searching for one but I don’t feel it is a high priority for him so I have one inbound from eBay.

When it comes to the transfer case not shifting it to neutral or 4 low. He says some transfer cases are just that way and you have to stop, turn off the engine, and put it in park before shifting but a higher quality fluid might help. We all know that is BS. I have been shifting that transfer case in and out of 4low for a decade and a half. I suggested to the mode ring to him but he poopoo’ that as a possibility. It was almost as if he could not fathom making such a mistake. He and I are going to have a bit more of a discussion about what’s the proper course of action. After all, it was I fine working condition when I took it to him just a bunch of leaks and maybe a stretched chain, now it simply doesn’t function.

Unfortunately, I believe I am headed for the infinite run around.

I wouldn't dismiss him on the case yet. The case won't want to shift between ranges if it's being spun, and right now your transmission doesn't have a neutral. The fact that you can sometimes get it to shift with the engine off points me away from a mechanical issue in the case and actually makes perfect sense because that's the only time the input isn't spinning.
 
So here is what I have heard from the shop now that they have had a chance to look at it:

Regarding driving forward in neutral - They are going to adjust one of the clutches (maybe the wrong term?) to fix that. They said there is trouble with the shift cable. Says the plastic fitting that connects it to the transmission is worn. It is a discontinued part. He is searching for one but I don’t feel it is a high priority for him so I have one inbound from eBay.

When it comes to the transfer case not shifting it to neutral or 4 low. He says some transfer cases are just that way and you have to stop, turn off the engine, and put it in park before shifting but a higher quality fluid might help. We all know that is BS. I have been shifting that transfer case in and out of 4low for a decade and a half. I suggested to the mode ring to him but he poopoo’ that as a possibility. It was almost as if he could not fathom making such a mistake. He and I are going to have a bit more of a discussion about what’s the proper course of action. After all, it was I fine working condition when I took it to him just a bunch of leaks and maybe a stretched chain, now it simply doesn’t function.

Unfortunately, I believe I am headed for the infinite run around.

Can you get it into each of the 4 modes by any method? Engine off, trans in park, neutral, or something involving wiggling the shifter back and forth to help the t-case shift? If you can find the 4 distinct modes, then the mode ring is correct.
 
I wouldn't dismiss him on the case yet. The case won't want to shift between ranges if it's being spun, and right now your transmission doesn't have a neutral. The fact that you can sometimes get it to shift with the engine off points me away from a mechanical issue in the case and actually makes perfect sense because that's the only time the input isn't spinning.

Good point…
Can you get it into each of the 4 modes by any method? Engine off, trans in park, neutral, or something involving wiggling the shifter back and forth to help the t-case shift? If you can find the 4 distinct modes, then the mode ring is correct.

Yes engine off in park.


What you guys are saying makes sense. It’s just hard to remain objective when I a fuming when they keep putting this on the back burner. I identified the issue May 4th and took it back to the shop on May 5th. They said they were short handed and scheduled an appointment to bring it back on Monday, May 22nd. I called to check progress on Friday, June 1st and they said “I was just got back from a test drive to see what is going on…”
 
Good point…


Yes engine off in park.


What you guys are saying makes sense. It’s just hard to remain objective when I a fuming when they keep putting this on the back burner. I identified the issue May 4th and took it back to the shop on May 5th. They said they were short handed and scheduled an appointment to bring it back on Monday, May 22nd. I called to check progress on Friday, June 1st and they said “I was just got back from a test drive to see what is going on…”

Each mode has to be tested. Just because the t-case shifter stops in 4 distinct spots means nothing as it will still do that with the mode ring reversed. You have to get it into each of the 4 spots and then start the rig and test them. The mode ring backwards usually shows up as 2 neutral spots.