NSG370 feels a little rough

[adventureboss]

So I replaced my six speed NSG370 in my TJ about 50k miles ago with a rebuilt High Impact after my friend unfortunately blew my original. I've been doing transmission fluid flushes every 20k-25k miles with Redline MTL. This gearbox normally doesn't ever really feel smooth. It has a notch when cold going into second gear, and it feels rather gritty when going into third at times. In 4low, when I shift from second to third it would straight up grind. Other times, it goes in just fine. Sometimes I have a hard time getting it into first gear, especially when cold. I can't remember if it's always been like this.

Weirdly enough, if I'm shifting full throttle at redline, it feels very smooth. During normal driving, it sometimes feels like crap. I would think it'd be the opposite especially because I'm sure I have some synchro wear at 50k miles on a rebuilt transmission. It's making me anxious and I'm wondering if I'm unfortunately going to be due for another transmission soon. I don't understand though because I don't drive my TJ like a racecar, and I've kept up with fluid changes and all. Then again, I've also heard these transmissions have never really shifted well and they aren't supposed to be smooth.

Thoughts?

 

[lBasket]

Oho another one of these threads

 

[OldBuzzard]

There are several (many?) threads on here about that tranny. A couple of recent ones:
This is why I hate NSG transmissions
NSG370 popping out of reverse

For many more, google: site:wranglertjforum.com nsg370

 

[Cooper Smith]

It has a notch when cold going into second gear

My NV2550 had the same problem. The NSG370 is known for shifter and synchro problems. Try double clutching when cold and see if it still feels notchy.

 

[JMT]

So I replaced my six speed NSG370 in my TJ about 50k miles ago with a rebuilt High Impact after my friend unfortunately blew my original. I've been doing transmission fluid flushes every 20k-25k miles with Redline MTL. This gearbox normally doesn't ever really feel smooth. It has a notch when cold going into second gear, and it feels rather gritty when going into third at times. In 4low, when I shift from second to third it would straight up grind. Other times, it goes in just fine. Sometimes I have a hard time getting it into first gear, especially when cold. I can't remember if it's always been like this.

Weirdly enough, if I'm shifting full throttle at redline, it feels very smooth. During normal driving, it sometimes feels like crap. I would think it'd be the opposite especially because I'm sure I have some synchro wear at 50k miles on a rebuilt transmission. It's making me anxious and I'm wondering if I'm unfortunately going to be due for another transmission soon. I don't understand though because I don't drive my TJ like a racecar, and I've kept up with fluid changes and all. Then again, I've also heard these transmissions have never really shifted well and they aren't supposed to be smooth.

Thoughts?

There are no known reputable rebuilders of the NSG370. Advanced Adapters sells an adapter for swapping in an AX-15. It’s a much better transmission, and they are still making them brand new.

 

[cpwolf]

There are no known reputable rebuilders of the NSG370. Advanced Adapters sells an adapter for swapping in an AX-15. It’s a much better transmission, and they are still making them brand new.

Eagle Transmission in Cedar Park, TX did a great job.
I got all the parts, sourced on what I knew it would need, was going to do it.

Then took it to them, and works excellent.

The B&M shifter makes it a lot better, that’s just me.

Kind of curious, you’re changing your Transmission Gear Oil every 25k miles?

That seems like a lot to me…I don’t think it would hurt it, just seems fairly often

 

[JMT]

Eagle Transmission in Cedar Park, TX did a great job.
I got all the parts, sourced on what I knew it would need, was going to do it.

Then took it to them, and works excellent.

The B&M shifter makes it a lot better, that’s just me.

Kind of curious, you’re changing your Transmission Gear Oil every 25k miles?

That seems like a lot to me…I don’t think it would hurt it, just seems fairly often

That’s good news for @adventureboss and @astjp2. See reputable rebuilder of NSG370 above.

 

[cpwolf]

That’s good news for @adventureboss and @astjp2. See reputable rebuilder of NSG370 above.

I was being sarcastic.....I think any good transmission shop can do this....if they source good parts. I took that out of the equation....I got all the parts, LOTS of threads on the NSG370.....A LOT of them on this forum.

I find it better to go to Google, type TJ FORUM NSG370 "whatever you want to add" and there are pages of information.

www.nsg370.com is also a place for some information.

I think now there is actually an internal shift fork that uses brass and not plastic connectors? I wish that was there when I had it rebuilt.
The 2009+ JK internals for rebuild, fixed a lot of the issues. I believe the design of putting so much into the shifter/shift tower, spring detente wise etc....which is why they're so dam expensive, has something to do with it.

 

[astjp2]

You will never hear me and nsg in a good way. I despise them, shitty Mercedes design that should have stayed in a car!

 

[astjp2]

That’s good news for @adventureboss and @astjp2. See reputable rebuilder of NSG370 above.

Eagle Transmission in Cedar Park, TX did a great job.
I got all the parts, sourced on what I knew it would need, was going to do it.

Then took it to them, and works excellent.

The B&M shifter makes it a lot better, that’s just me.

Kind of curious, you’re changing your Transmission Gear Oil every 25k miles?

That seems like a lot to me…I don’t think it would hurt it, just seems fairly often

25k miles? I can’t even get 25 miles

 

[astjp2]

I am going with a np435 next, just not worth the headache of stay stock

 

[astjp2]

I was being sarcastic.....I think any good transmission shop can do this....if they source good parts. I took that out of the equation....I got all the parts, LOTS of threads on the NSG370.....A LOT of them on this forum.

I find it better to go to Google, type TJ FORUM NSG370 "whatever you want to add" and there are pages of information.

www.nsg370.com is also a place for some information.

I think now there is actually an internal shift fork that uses brass and not plastic connectors? I wish that was there when I had it rebuilt.
The 2009+ JK internals for rebuild, fixed a lot of the issues. I believe the design of putting so much into the shifter/shift tower, spring detente wise etc....which is why they're so dam expensive, has something to do with it.

I would disagree about any shop doing a good job…

 

[cpwolf]

I would disagree about any shop doing a good job…

Any “Good” shop, to clarify, and yeah I’ll disagree.

Strange if you got a rebuild and can’t go 25 miles, you need to choose a better shop maybe

 

[astjp2]

So hi impact, Randy’s ring and pinion and zumbrota, 3 different shops