t-case grinding in 2wd, goes away with front DS removed.

[blistovmhz]

Posted this on my 5.3 swap thread as well, but I suspect I'll get better visibility with a new post, and perhaps help someone with the same issue down the road.

I put together a hybrid case. np231j case and output, np241c input gear, and some np231c internals (chain, front output, and chain gear on the 231j main-shaft).
Case has worked fine for a few months behind the v8. I don't think the problem is specific to this hybrid, but probably just a common t-case failure.

Was out doing some high speed wheeling Saturday (broke a few things, but t-case was not among the things giving me problems at the end of the trail).
Sunday we drove out to a lake (all highway). When we headed home at the end of the day, as soon as we got up over about 35km/h we started hearing some grinding/slapping coming from around the t-case. Throw it in 4x4 and the noise goes away, but as it's only a 231, couldn't drive home like that.
Pulled the front driveshaft off and tried again in 2wd, no problem. Noise is gone.

So:
2wd with front DS attached - grinding/slapping over 35km/h.
4wd with front DS attached - quiet.
2wd with front DS removed - quiet.

I figured it had to be the chain so this morning I got under the Jeep with a high speed drill, put the Jeep in 2wd, and spun up the front output shaft (with a 1 1/8" socket). No noise and now confused. If it's the chain, it SHOULD be making noise.

I've gotta pull the case anyway as I've got a leak between the case and trans, and I wanted to replace the front half of the case with an older 231j because I didn't match up the input to the correct ring gear to begin with (whines a bit, and probably decreases longevity, but it does work and I'm confident it's unrelated to this new grinding noise).

Who's got an idea? A busted snap ring or a stretched chain, or even a bad front output bearing I figure should've shown me some noise when I spun it up with the drill. I'm headed back outside to pull it out of the Jeep now, but perhaps someone can save me some time. It's always possible the driveshaft itself was making the noise (though it really didn't sound like a DS) and I've got a new one from TomWoods on it's way already.

 

[cal]

It sounds like your chassis isn't strait and is warping the housing.

 

[blistovmhz]

It sounds like your chassis isn't strait and is warping the housing.

Sarcasm?

 

[cal]

Could you tell?

 

[blistovmhz]

Come ON! This is a totally legit question!

It's just ****ing me up that the grinding is clearly being caused by the front DS spinning the front output, but then can't reproduce issue with a drill. Makes me think somehow the DS was making the noise, but .. yea it's a shitty DS but DS's don't really make this noise.

 

[cal]

Do it again, but pry down on the front output to simulate the weight of the driveshaft on the output bearing.

 

[cal]

If that doesnt work, put the drill on the other end and spin the whole driveshaft.

 

[blistovmhz]

Do it again, but pry down on the front output to simulate the weight of the driveshaft on the output bearing.

Did. No change. No noise.

If that doesnt work, put the drill on the other end and spin the whole driveshaft.

How am I going to attach a u-joint to a drill? Also, the DS that was on there, isn't going back on. I had to destroy the hell out of it to get it off the front output (stripped bolt head). Had to break the CV ear right off.

 

[cal]

myself, i'd use a welder and something pointy. On your driveshaft that is, I probably wouldn't mutilate my own..

but beyond that, try taking it apart and seeing what you see.

 

[blistovmhz]

myself, i'd use a welder and something pointy. On your driveshaft that is, I probably wouldn't mutilate my own..

but beyond that, try taking it apart and seeing what you see.

So there was definitely some chain slap.
Current case with the noise.

I've for several cases and chains to choose from. As I said, I wanted to swap out to an older style front half with the old style course cut ring gear anyway.

But, that said, should I be hunting down a new 241 chain, or is there any possibility the chain wasn't the issue? I'd hate to replace the chain and find out something else was making the noise, or worse, the chain was slack because of a defect in the case.
I really like the idea of the 1.5" wide chain as opposed to the smaller 1", but is the 1.5" really necessary for my rig? Do the 1" chains break/stretch often? The 1.5" 241 chain I'm using came from the wrecker from an unknown donor. Just lucked out and found the 241 lying on the ground and I needed the input gear for my 5.3 swap.
I also find it super suspicious that the noise just showed up all of a sudden, and it was LOUD. Like, I pay ridiculous attention to new noises and smells emitted from my Jeep cause I'm paranoid as ****. The sound was NOT there on the mild highway drive to the lake, and was very obvious the second we pulled out of the parking lot. I almost suspect the chain slap wasn't the noise I was hearing (though it was clearly there), and that the DS was somehow causing the noise.

Suggestions? Ready to re-assemble (unless I want a new 1.5" chain) .

 

[cal]

I dunno. I solved my transfer case questions with the application of an altas.

 

[blistovmhz]

Stuck the old internals into the new (older) front case half. Tested a theory. I think my linkage bent somehow and was causing the case to engage the tip of the chain gear syncro. Sure sounded like the issue on the bench. Case is back together with a different shift .... Plate thing so I get true neutral again!
Will have the case back in tomorrow. The girl made me come in for food.

 

[blistovmhz]

Okay, so I'm pretty sure that was it. Did a quick write up explanation on another thread to help someone else out (hopefully) and reposting here as I've got a more appropriate title for the thread.

Assuming your problem is as follows:

1. T-case makes a loud clicking at speed, in 2wd.
2. Noise goes away in 4wd.
3. Noise goes away with front driveshaft disconnected.
4. Front diff, ujoints, and driveshaft are known to be good.
5. The sound is a loud, high speed click that increases in speed with wheel speed.
6. Problem is not reproducible with the vehicle jacked up off the ground.

Pulled the case for inspection, as (mentioned above) I wanted to replace the front case half with an older style which had the old style gear cut to match my 241c input gear anyway. At first, I thought it was chain slap due to some slight wear on the front case half above the front output, but even without the rear case half on, I couldn't stretch the chain far enough to cause any contact. I figured the markings must have been from another life and another older chain.

Finally figured it out after an hour of really thinking about the noise and what in the case could cause it. On the main shaft you have your range selector (furthest forward) and then your shift collar (which locks the main shaft to the chain sprocket when in 4x4). The leading edge of the shift collar splines is beveled at a 45* angle to make engagement smoother. If you pull the shift collar slightly up (back, towards the chain sprocket) just enough to make the collar splines barely touch the chain sprocket, and give the front output a spin, you'll get your noise.
So, in my case (and really, I see this question posted all over and rarely with a solution), the shift collar was slightly engaged on the chain sprocket because my shift lever had bent slightly, so when I put it in 2wd, the shift collar didn't quite go to the full forward position.

Possible causes for partial shift collar engagement:
1. Bent shift linkage.
2. Shift linkage out of adjustment.
3. Something stuck in the front of your shift lever (in the cab) preventing it from going full forward into 2wd.
4. Bent shift fork (pretty ridiculously unlikely unless it was bent while the case was apart).
5. Warped t-case.
6. T-case not bolted properly to the transmission in the first place, then something jolts it forward into the transmission into the proper location. Now your linkage is incorrectly adjusted about 1mm back.

Test:
Verify the noise goes away when you disconnect your shift linkage and manually force the t-case lever into the 2wd position. If you still have a noise, you probably have either a bent shift collar or the problem has nothing to do with your t-case.


I just got my case back together last night and then the girl made me come in and eat (what a bitch right?) so I haven't re-installed to test, but the sound it made when I pulled the shift collar back to partially engage the chain sprocket is EXACTLY the sound we heard, plus I did confirm my bastardized reversed shift linkage was in fact, slightly bent the right direction for this problem to make sense. I should've made a video because when the case is apart and you see this problem in action, it becomes VERY OBVIOUS.

Hope this helps someone.

 

[XJ_Rudolph]

I dunno. I solved my transfer case questions with the application of an altas.

hahahahaha sounds like your doing something right!!!

And I was going to say its probably your shift linkage....but it looks like you already got this cat in the bag!