NSG370 Transmission Question

[wincod75]

First off i'm brand new to this site so I apologize if this thread is in the wrong forum.

I have an 06 TJ and am experiencing a knocking noise in what seems to be the trans? From my research thus far I'm lead to believe that even though there is likely a problem, is is a common problem to have...

Trans: NSG370
Transfer Case: Np231
Diff ratios: 4.56
Dana 44 rear, 30 front
3.5 inch lift
SYE
35 in. BFG KM2s

I've owned the Jeep for about 4 years, within the first 2 years I had to replace the clutch. I'm now experiencing more clutch "noise," but specifically looking for feedback around the knocking noise i'm hearing from what I believe to be the transmission.

The noise is only present when in gear; the knocking gets faster as I accelerate. It only happens in 1st, 2nd and 3rd. If I run out 2nd gear and hit 3k RPMs the noise goes away; seemingly only makes the noise in low gear, low rpms. No noise at all in 4th, 5th or 6th. The noise also happens when I'm in gear and decelerating by gently releasing the clutch. I can also feel the knocking in my shifter.

The noise is very inconsistent. Sometimes its there and just like that it will go away. Any input/thoughts are greatly appreciated. The local shop that does the heavy lifting on the Jeep tried telling me this is the worst trans Jeep ever used and all this jazz; which is not what i'm finding out after researching online. Sounds like the guy just wants to replace a trans. When the clutch was done about 1.5-2 years ago, the flywheel was not touched, nor was the input shaft, just the clutch... pressure plate, springs, throw out bearing, etc.

Thanks in advance!

 

[ac_]

Hello, so I agree it is probably not the best Jeep trans especially the first few years of it. I used to rebuild transmissions back in the day, but admittedly never have been into your transmission, but what it sounds like to me without driving it or hearing the noise is it is probably a broken tooth on the counter shaft in the trans. When you are in 4th gear you are one to one with the wheels, so there is no load on the counter shaft. I believe 5th and 6th are different degrees of overdrive, so your still not pressuring the counter shaft. So specifically maybe a bearing lost a ball, and it is floating in the bottom of the trans or the countershaft has a broken tooth.

From what you described I would bet it is in your trans. If it was your clutch, I believe it wouldn't matter what gear you were in it would rattle in all gears. The fact that it happens only under 4th leads me to believe it is probably the counter shaft.

 

[wincod75]

Thanks for the input!

Forgot to mention I did do a fluid change on the trans last weekend. The drain plug did have a fair amount of fines, but nothing chunky came out of it, that's not to say there's nothing laying in there still... just a heads up.

FWIW I've definitely got clutch issues as well, but really just focusing on the trans noise as I agree, I think this noise in particular is coming right from the trans. I get a heck of a chirping noise sometimes too, but that's directly related to if and when I press the clutch; this other noise is as inconsistent as the trans noise.

I'm trying to decide what to do with it and when. If there's a better/different transmission to swap in or if i should get this one fixed. Also, do I get it fixed now or just run her until she goes and go from there?

 

[ac_]

Thanks for the input!

Forgot to mention I did do a fluid change on the trans last weekend. The drain plug did have a fair amount of fines, but nothing chunky came out of it, that's not to say there's nothing laying in there still... just a heads up.

FWIW I've definitely got clutch issues as well, but really just focusing on the trans noise as I agree, I think this noise in particular is coming right from the trans. I get a heck of a chirping noise sometimes too, but that's directly related to if and when I press the clutch; this other noise is as inconsistent as the trans noise.

I'm trying to decide what to do with it and when. If there's a better/different transmission to swap in or if i should get this one fixed. Also, do I get it fixed now or just run her until she goes and go from there?

As far as the clutch does it chirp when you push in the clutch or let it out? Well either way if it the front bearing could chirp if it is bad and could explain your countershaft issue in that if pieces of it came apart and went in the bottom of the trans it could rattle also if the bearing is bad it could squeal is it stops and starts. But also could be if you push it could be the T/O bearing or the input bearing if it squeals when you let it out. In any case it will be evident when you pull the transmission.

I can't tell you what to do or really even suggest. I am not sure how you drive or what your Jeep is used for. It sounds like it is heavily modded, I am not sure of your mechanical ability.

My immediate thoughts are just fix the one you have because there will be no more modding necessary, and it will be expensive, but you know what to expect at the end, but if you want a quieter trans you can put a ax15 in, but there may be some driveline mods necessary. That said if you are going to change the trans maybe consider a sm420 chev. That has a Granny low gear which is pretty bitchen, but you give up your overdrive. there is also a 4sp Jeep trans with a granny too, but I don't remember the name, but if you do a lot of freeway driving the granny gear will loose its appeal. Plus there will be more adapting to get it in there. Those are just options, but if it were me, I would probably just rebuild the one that is in there.

Too bad you don't live in AZ, we could rebuild it in my garage with some beers.

 

[wincod75]

Regarding the clutch; it's about as inconsistent as the knocking noise, but it will chirp when the clutch is out, if i tap the clutch with my toe the chirping gets louder, but when I push the clutch in it goes dead silent. It's not always true, but 99% of the time this only happens when it gets cooler out. All week its been mid 70s here and I haven't heard it chirp one time. This morning it was 40s and of course there it was. After 15 min of driving though it went away.

As far as the trans, thank for the input and advice. I bought this Jeep with most of the work done to it; it was built to be a crawler, but the most i'll be using it for is on the beaches here in NC. The most highway driving I do in this thing anymore is 45 min tops. It's simply not setup for long highway trips; I don't trust going more than 80mph in it and even that's pushing it.

I appreciate your eagerness to help! If i was in AZ I would take you up on that offer. I have debated finding someone local to help me out, my only fear is getting everything back together correctly and having the tools to do the job. My old man and I used to rebuild trans and diffs out of dump trucks and big rigs so i'm not illiterate when it comes to mechanical work, but i'm 99% positive I don't have the tools to do this job myself.

My only fear with rebuilding is if I end up in the same boat X miles later. The Jeep only has 80K miles on it. I can honestly admit I drive like an old lady and even more so after researching the trans and understanding the nature of it. That being said; I did have to fix a lot of stuff that the previous owner messed up which makes me wonder if thats why the trans is wearing prematurely... Rear diff was in wrong, major pressure on the clutch, drove horribly, which thus far has lead to me having to replace a lot of other stuff i'm convinced all resulted from this major mistake, but who knows...

 

[ac_]

I do ubderstand your fear of taking it someplace. I grew up as a technician but changed careers late in life. I can afford to take my cars to the shop, but dont for thise same fears. But you may have to bite the bullet and just get it done.

It is rare for the trans to break at 80k the reason I talk down about your trans is even when it is not broken they are still noisey by nature. Not rattly noisey. It soundd like it may not have been maintained well and maybe even abused. Maybe for the fun of it see if you can find a used one on craigslist? That is a gamble to o because there is nothing stopping you from selling yours if you replace it, and people can be a-holes. Usually not though I have had pretty good luck buying cores and parts from craigslist.

Good luck and keep us posted.

 

[wincod75]

Yea, I often find shops to abuse their customers; typically by performing work that simply doesn't need done, but I digress. Thank you for the input, I greatly appreciate the help. I'll keep you updated with how things progress.

 

[Daredevil96]

Currently driving a manual transmission NSG370 on a 06 Rubicon.

I hate to revive this thread BUT... OP, what did you end up doing? I’m havinf the same issue. I know what your knocking sound sounds like and the chirping on the clutch when I press it slightly. At first, I thought the knocking noise was due to the pinion angle but I’m not so sure anymore after reading that it happens to you too.

I notice the knocking noise when I’m on 1st, 2nd and 3rd gear and I’m accelerating, then I let go of the accelerator (to let the Jeep move on it’s on...ps I also hear something rubbing, like metal to metal), THEN right after, if I need to press the clutch pedal to go into neutral, it makes the knocking noise. To me it sounded like the U-joints were rubbing but I had a friend check the other day and he said my U-joints look fine and did not seem to be worn out by any metal to metal rubbing.

What was it that you did to it? The Jeep drives fine but I think sooner or later I need to replace the clutch.

 

[TJ Hunnicutt]

Daredevil96, it is very unlikely that the OP has even been on since the last post in this thread (he only had 4 posts and they are all on this thread).
Your best bet will be to start a new thread with your issue. I'd love to help myself but am not terribly familiar with your tranny (I just got my '06 Rubi and haven't even driven it except to get it home). The best advice I can give, beyond posting your question on a new thread, would be to go for the clutch and throw-out bearing replacement because it's inexpensive to do and might end up solving your problems. EDIT, that is, assuming you do it yourself.

 

[Daredevil96]

Daredevil96, it is very unlikely that the OP has even been on since the last post in this thread (he only had 4 posts and they are all on this thread).
Your best bet will be to start a new thread with your issue. I'd love to help myself but am not terribly familiar with your tranny (I just got my '06 Rubi and haven't even driven it except to get it home). The best advice I can give, beyond posting your question on a new thread, would be to go for the clutch and throw-out bearing replacement because it's inexpensive to do and might end up solving your problems. EDIT, that is, assuming you do it yourself.

That is probably what I’m going to end up doing. Replace the clutch and all. The Jeep only has 60k miles on it and I got it a year ago. Hopefully once I replace the parts, it will be good as new. I’m going to post this on another thread anyway to see what others have experienced. Thanks!

 

[Farmergreg]

Is there a possible chirping issue that can be caused by the front DC joint in the driveshaft?

 

[Daredevil96]

Is there a possible chirping issue that can be caused by the front DC joint in the driveshaft?

How can I identify if it’s coming from the DC joint? Do I have someone go under the Jeep while I press on it to hear where it’s coming from?

 

[Farmergreg]

How can I identify if it’s coming from the DC joint? Do I have someone go under the Jeep while I press on it to hear where it’s coming from?

I remember reading here on the forum that a dry/failing DC front driveshaft joint can produce a chirp when failing.

There was also a thread about the failing DC Joint causing the transfer case to crack.

Not exactly sure how to identify the cause as I haven't experienced the problem....yet.

Edit to add: just suggesting the chirp might be related to the driveshaft rather then the trans.

 

[Farmergreg]

How can I identify if it’s coming from the DC joint? Do I have someone go under the Jeep while I press on it to hear where it’s coming from?

Maybe mount a go-pro camera underneath and drive it.