NV3550 Transmission 2nd Gear Shifting Issues

[bromel]

The NV3550 usually makes a rumbling noise when sitting in neutral with the clutch out. Sounds like gears rattling and rolling over. It's nothing to be worried about—just the input shaft spinning the bearings, and it's loud because the TJ has no sound-proofing. It usually gets louder the longer the TJ has been running and the hotter the transmission gear oil is. (Adding Red Line MTL usually helps quiet it).

As for the slipping—that's obviously worrisome. Hopefully it's just the boot as your mechanic says. It should be up to them to get this right.

 

[ebenk17]

The NV3550 usually makes a rumbling noise when sitting in neutral with the clutch out. Sounds like gears rattling and rolling over. It's nothing to be worried about—just the input shaft spinning the bearings, and it's loud because the TJ has no sound-proofing. It usually gets louder the longer the TJ has been running and the hotter the transmission gear oil is. (Adding Red Line MTL usually helps quiet it).

As for the slipping—that's obviously worrisome. Hopefully it's just the boot as your mechanic says. It should be up to them to get this right.

Thanks for the quick response. That makes me feel a lot better! I'm definitely not going to accept bad work, so I'm going to make sure it all gets fixed. I actually have a video clip with the sound it's making.

Please let me know if you think this sound is normal. I appreciate the help!

 

[bromel]

Yeah that sounds like my NV3550 right after a cold start. After I drive for a few miles, that "wirrrr" sound becomes more like a rumble.

 

[03sahara]

Did you put a new clutch in or the old one maybe your slipping could be caused by that?

 

[ebenk17]

Did you put a new clutch in or the old one maybe your slipping could be caused by that?

I did replace the clutch too. So I hope not!

 

[Goatman]

Clutch would slip in all gears. But not sure what you mean by 'slip'. Like, actually slipping similar to a clutch? Or slipping during a shift? A gear on gear transmission can't really slip in gear unless the gears are slipping on their rails. And that would be total slipping with no foward movement in that gear. Or do you mean slipping out of gear? If it's all your lower (shifter location) great are falling out of gear it is likley the shifter is hitting something that blocks full shifter movement. Pull your center console and look for what the shifter is bumping into..

 

[ebenk17]

Clutch would slip in all gears. But not sure what you mean by 'slip'. Like, actually slipping similar to a clutch? Or slipping during a shift? A gear on gear transmission can't really slip in gear unless the gears are slipping on their rails. And that would be total slipping with no foward movement in that gear. Or do you mean slipping out of gear? If it's all your lower (shifter location) great are falling out of gear it is likley the shifter is hitting something that blocks full shifter movement. Pull your center console and look for what the shifter is bumping into..

Sorry I meant to say slipping out of gear. Like when I'm driving in second, if I don't hold it down the shifter may pop into neutral. Same happens in 4 and R. I'll definitely check to see if something is stopping the shifter from fully moving.

 

[Goatman]

Almost guaranteed it is the shifter hitting either the tin or (in my case) the center console. Loosened a few screws,(actually were already loose) shifted the console back, all good.

 

[ebenk17]

Yeah I realized that it also slips out of 3rd. I just dropped the jeep off to the shop yesterday to have them address these issues.
Hopefully it's no big deal!

 

[ebenk17]

So I have an update that I'd like to hear opinions on.

My bad decision of rebuilding the tranny, may have gotten worse as it has been a headache ever since. At first, as I mentioned before, the gears were slipping very frequently. I took it back to the shop, they adjusted the boot and replaced a bushing on the shifter. This definitely seems to have helped, but the gears still slip - just not as often. Except for third gear, that one slips often.

Basically, if I put it in third (it has also happened in 2nd and 5th) while accelerating, its fine. When I let off the gas, it slowly slips out of gear. Any idea what this could be?

My mechanic said he was going to replace the shifter to see if that helps, and if not he will replace the transmission. I want to know what you all think to make sure we are making the right considerations here.
Thank you so much!

 

[xxdabroxx]

You might try taking the console out and driving it without. If the shifter isn't contacting anything then the issue would be internal to the trans. The consoles come out pretty easy. If it's only the lower 3 gears on the pattern I'd think it's the shifter contacting something it shouldn't. But I'm no manual transmission expert either.

Keep working with the shop and let them make it right. I'm sure they don't want an angry customer giving them a bad name. Mine is losing the 2nd gear synchro too so I'm probably headed in your direction sometime soon. I don't want to swap to the ax-15 if I don't have to.

 

[ebenk17]

You might try taking the console out and driving it without. If the shifter isn't contacting anything then the issue would be internal to the trans. The consoles come out pretty easy. If it's only the lower 3 gears on the pattern I'd think it's the shifter contacting something it shouldn't. But I'm no manual transmission expert either.

Keep working with the shop and let them make it right. I'm sure they don't want an angry customer giving them a bad name. Mine is losing the 2nd gear synchro too so I'm probably headed in your direction sometime soon. I don't want to swap to the ax-15 if I don't have to.

Thanks for the quick reply!

Yeah, I wanted to keep the original transmission too which is why i went for the rebuild. It seems to be happening in all gears, so I didn't think it was the console. It's a shame because everything else seems to be working correctly and very well. It just makes me worry that all may not be as good as it seems.

It does seem like they are trying to fix the issue, I'm just getting tired of waiting around and bringing the jeep back and forth.

 

[Steel City 06]

Personally I would just bite the bullet and do the AX-15 swap. Then at least you would get 100,000+ miles of performance before you have to look at it again. You could keep the NV3550 to work on in your free time or sell it for the core. Maybe the shop will refund you if they get to keep the core.

They're not terribly expensive, and the new ones are often cheaper than remanufactured NV3550s.

https://www.novak-adapt.com/catalog/transmission/transmission-packages/ax15-package

 

[03sahara]

Even a used ax15 is a good option I installed one with close to 200k mi and it’s still going strong. My nv3550 was grinding most gears by 60k mi. It’s also a direct swap and looks the same and the gear ratios are only slightly different.

 

[Goatman]

Agree with above. Swap to the AX-15 and be done.

 

[ebenk17]

Thanks, all. I'm stuck waiting to see if this mechanic can make it right. If he can't, I'll definitely ask for my money back and do the swap to an AX-15 or terminator.

 

[StevePannell]

So please don't make me feel worse guys, but I made a bad decision and had it rebuilt based on price and quickness.

I'm upset about my decision because I've encountered a couple problems. There's a humming when the Jeep is in neutral and it stops to a silence when I press the clutch in. Does anyone know what might be the issue?
Also, the 2, 4, and R all slip. I called and the mechanic said it may need a boot adjustment. I'm bringing it back to the shop on Tuesday I just want to be fully informed when I do. I'm feeling scared that nothing was done right.

Did the mechanic resolve your issue? I just had mine rebuilt and not happy with results. Slips out of second gear and sounds odd. I will be taking mins back but don’t know what to expect.

 

[StevePannell]

Did the mechanic resolve your issue? I just had mine rebuilt and not happy with results. Slips out of second gear and sounds odd. I will be taking mins back but don’t know what to expect.

Sorry for the delayed response. They ended up using an AX15, this one failing already and dropped off at their shop last night. Very disappointed to say the least!

 

[Steel City 06]

Sorry for the delayed response. They ended up using an AX15, this one failing already and dropped off at their shop last night. Very disappointed to say the least!

You can get brand new AX-15 transmissions for not much more than a reman:
https://www.novak-adapt.com/catalog...R5WejnocfHAaiAulwwnk49gc-eIkNxuMDFCO4CifHbWn4
Novak isn't the only source, just posted them as an example.