Weird NSG370 shifting issue

dodgeboy

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Joined
May 13, 2022
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37
Location
Michigan
First post here. Looking forward to being a part of the community. I've owned several jeeps in the past (CJ, YJ, TJ and JK).

I recently acquired an '05 X with the 4.0L and NSG370 6-speed. I'm noticing a weird shift behavior with it. When cold, it shifts relatively ok while maybe slightly notchy into 3rd and 4th. As the transmission warms up, the "notchiness" increases to a slight grind into 3rd, 4th, and 5th. It's not a high-speed gear mismatch screech, but rather a "dut dut dut" feeling as it goes into gear. Of course I figured the synchros were dying. The weird part is I only notice this if I shift under 2500 RPM. If i shift at or above 2500 RPM, it shifts normally. Downshifts are also completely normal at any RPM. I put amsoil synchromesh in it and it improved slightly. There was a significant amount of shavings on the drain plug. About 400 miles later I tried redline MTL and it is pretty much the same as the amsoil. Zero shavings on the drain plug the second time. If the synchros were bad, I'd expect it to get worse at higher RPMs and also have issues downshifting. If I shift slowly (2 sec delay between gears) and rev match, it shifts perfectly. I was told by the seller that the transmission was "redone" last year because it was popping out of gear. I was shown paperwork supporting the trans work. Unfortunately, the paperwork was not specific as to what was done to the transmission.

I feel like I could probably drive it around forever like this without making it worse, as long as I shift slowly. But I still wonder what is going on with it. Any ideas?
 
Changing oil is the go to solution around here, after that people go straight to rebuild 5 speed swap.
Most notable issue is 6th gear popping out, and around 2nd and 3rd gear grind. I have a fairly decent NSG370 in comparison to all the complains around here, but from time to time it leaves me wondering. I used to live in apartment complex on the hill, my reverse was grinding every day after parking on the slope. Then there are periods of random 2nd to 3rd grinds that leave me wondering if it is my driving, my shifting, did i push clutch all the way in or if it is weather. Last 3 month have been butter smooth, so wtf?
My oil changes are at 15000 mile intervals with same amount of powdery shavings on the magnet. Without seeing other samples, it is hard to say what is considered excessive.

One thing for sure, you have to adapt to this transmission and not the other way around. Other than that, trying to get in touch with previous owner or the shop that did the work is probably your best bet.
 
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That's a good point. I will try to contact the shop and see if they are willing to share any details of the work they did. I've not had any issues with it popping out of any gear, and the shifter linkage feels very solid. The previous owner claims he never noticed it, but he may have been shifting above 2500RPM.
 
Just drive it until it stops going into reverse and then ax15 swap it or look into a rebuilt unit. I have never found this transmission to be user friendly
 
by the looks of google search, it is at least a worthy substitute, consensus seems to be that NSG370 is the weakest in comparison to AX15 and NV3550.
When it comes to addressing issues of NSG370, in every post i have seen people say that it is expensive. Do a bit of searching, i have found plenty of post about swapping to AX15, we also have a member that is currently going through a swap, he may be able to help you with any questions
https://wranglertjforum.com/threads/nsg370-to-ax15-swap.61396/#post-1120615
 
I had problems with the original in mine, at about 80-90k miles, popping out of reverse. Replaced at 110k with a brand new MOPAR unit in 2013, and have not had issues since.
 
Is the AX15 considered an upgrade from the NSG370?
I cant argue about upgrade or not but here is what I can tell you..when an nsg370 needs rebuilt it needs everything and the parts are expensive and special fixtures are required to rebuild. I called around and most places wouldn't even touch it. I found a friend of a friend that worked at a transmission shop and he rebuilt it to the tune of $1200 cash/no receipt etc..installed it and it didn't pop out of reverse anymore but was hard to get into second gear and was generally a pain in the ass to shift..hindsight told me to skip the rebuild next time and save time and money with the ax15 swap.
 
Don’t follow my xample,
I waited too long !!! 🙈😊
• I couldn’t keep my NSG370 in first gear
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