What's wrong with the 6 speed in the TJs? Is reliability really a concern on these gearboxes? Or are there other reasons why people seem to feel very negatively towards them? I have one in my 06. It's nothing special but it gets the job done? I don't really have any complaints about it.
Why is the NSG370 so hated?
- Thread starter adventureboss
- Start date
I have a complaint or two. First, I think the overdrive is a bit too numerically high. Second, it's not an auto (now that I know better). Other than that I've had no problems with mine.
Still kicking after 18 years. Reverse has always been a bit of an annoyance. 
Some people report having issues with reverse and 1st to 2nd gear (I think either popping out or hard to engage). Others report no issues. Seems to be hit or miss. From what I have read, there was a small effort to bandaid the issues by the manufacturer, so later models may be slightly more reliable, but the transmission is still known for the aforementioned issues.
Its main redeeming quality is its gear ratios.
Its main redeeming quality is its gear ratios.
JKP
TJ Addict
Got about 280K on mine, no issues.
Clutch made it 270K.
It's an 06, so no reverse issues.
Clutch made it 270K.
It's an 06, so no reverse issues.
The ‘05 seems to be more problematic than the ‘06. The shift fork is over-engineered German bs. 1 and 2 can be a real bear and R can be difficult to get into and then pop out. Mine got so bad I feared I would not be able to back up one day. Here’s the main thing…
A reliable rebuilder doesn’t exist at this point.
I swapped to a 42rle. Another possible swap is to an AX-15. Far more reliable, but the gear ratios are not as desirable as the NSG370.
A reliable rebuilder doesn’t exist at this point.
I swapped to a 42rle. Another possible swap is to an AX-15. Far more reliable, but the gear ratios are not as desirable as the NSG370.
Most of my disdain is right there as you noted. They shift like crap, I've been around many that were the second and third replaced under warranty by the dealer. They just really aren't that special and you still need all the same gearing in the diffs and t-case that all manuals need for anything serious.
It's a rumor based on those that can't drive a standard transmission while 4-wheeling. They think the only way to go is an Auto. I like my 6 speed, it works well. 
I've had two. The first one in an '05 I bought with 54k miles and sold around 80k miles. I had no issues with it and at the time (2010) I wasn't even aware that they had any issues....the forums were abuzz with burping gas tanks and grenading OPDAs but I don't remember any talk of the NSG370 issues having shown up yet. I actually love the ratios, I think they're perfect.
The shifter is rather vague. The AX15 (the 5 speed used through 1999) by comparison feels like a short throw Porsche box after shifting the NSG370. Though the shifting isn't ideal, I could get past it if not for the real reason I hate it. My understanding is the box was originally designed for a sporty car like the Chrysler Crossfire, and with a shift lever just a few inches long I could imagine it feeling more precise.
My big issue is that too many of them end up having issues popping out of gears or not wanting to go into gears. Multiple forum members here have replaced theirs either with new units or different transmissions altogether, just in the past 2 years. Multiple causes have been identified, from tooth damage due to attempting to shift into a gear at an inappropriate time (like reverse while still slightly rolling forward), worn pads where the forks ride in the hubs, bent shift rods (they're stamped steel plate instead of more robust rods/shafts). Jeep supposedly fixed the issue in 2006 and later vehicles with a new set of reverse parts, but my 06 still had the issue and I wheel with guys with JK's made after 2012 that still have it. I don't know the specific cause of mine, but it eventually (around 120k miles) got to where it wouldn't stay in reverse against any kind of resistance. It would usually stay in while backing out of a parking space on level ground or downhill, but if I tried to back up my driveway, or heaven forbid a log or a rock, it took hard force with my hand on the shifter to hold it in, which made wheeling almost impossible in specific situations where I needed a hand on the wheel and one on the parking brake. When I ended up in a situation where my hand throttle is the only thing that saved me from paying for an expensive recovery out of the bottom of a creekbed, I ordered an AX15 and swapped it in.
I miss the ratios but putting another NSG370 would have eaten away at my sanity always wondering when it was gonna crap the bed again.
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I'm with @freedom_in_4low.. I've had problems with the NSG370 since day one. Even with a replacement unit, my 2nd gear syncros are already starting to go. I'm swapping in an AX-15.
Also, this is a good watch.
Also, this is a good watch.
Why is the NSG370 so hated? Because nobody talks about it when it's doing its job correctly, and everybody talks about it when its not.
Mine became quirky going into reverse (or rather, not going into reverse). It feels like it's in reverse, but pops out when I let out the clutch. I found that if I always put it in first, bump the clutch so the Jeep rolls a fraction of an inch, then hit reverse while its barely moving, the shifter goes in deeper, and it never pops out. I can live with that, and I don't expect it to degrade any more since I'm not grinding it.
Mine became quirky going into reverse (or rather, not going into reverse). It feels like it's in reverse, but pops out when I let out the clutch. I found that if I always put it in first, bump the clutch so the Jeep rolls a fraction of an inch, then hit reverse while its barely moving, the shifter goes in deeper, and it never pops out. I can live with that, and I don't expect it to degrade any more since I'm not grinding it.
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I hate how you never really know you've made it to a gear detent and the shifter shakes so much if you let go you might get smacked reaching for the knob again.
My only experience with them is in the 12 and 13 JKs. I tried like hell to get my wife to buy an auto.
I will say a Centerforce clutch and extra heavy flywheel seems to help with crawling. But less miserable is still miserable.
-Mac
My only experience with them is in the 12 and 13 JKs. I tried like hell to get my wife to buy an auto.
I will say a Centerforce clutch and extra heavy flywheel seems to help with crawling. But less miserable is still miserable.
-Mac
View attachment 570141
Das ist große Scheiße! Zie Germans macht alles sehr gut, Amerikaner Schwein!*
* If I recall correctly, @mrblaine referred to the shift fork as a "polio derivative leg brace multi-jointed piece of crap"...nailed it, I'd say...
View attachment 570145
AX15 for comparison.
The reverse issue was resolved with redesigned parts. I'm having good experience with my High Impact rebuilt. Never pops out of gear. No question if it's in gear or not.
Some say High Impact results vary. Most haven't actually invested in a professionally rebuilt example and regurgitate bs they've heard.
As always, YMMV
Some say High Impact results vary. Most haven't actually invested in a professionally rebuilt example and regurgitate bs they've heard.
As always, YMMV
My main problem with it is that first gear is nowhere NEAR low enough. I get the feeling that it *is* a bit fragile if you slam through the gears - I think people who don't know how to shift a transmission correctly/gently exacerbate the shift fork issue. Mine's an '06 that I bought at 127K, so Goddess only knows how it was treated before I got it. The 1st syncro is a bit worn, as is the reverse, but if they are put into gear correctly, there's no problems. Reverse is a bit "subtle" to feel going in - I can tell if it hasn't gone that last little bit, so I just ease back on the lever slightly as I let out the clutch and it slides in. Reverse and first don't really need syncros anyway.
Maybe @NovakConversions will come out with a kit to install the new Bronco 7 speed in a TJ - it seems to have the right ratios from the brief look I had at it. How good/bad it is, I have't a clue...
I have no problems shifting the thing - it shifts like a truck transmission, it isn't a sports car and I think that's where some folks end up having problems.
Maybe @NovakConversions will come out with a kit to install the new Bronco 7 speed in a TJ - it seems to have the right ratios from the brief look I had at it. How good/bad it is, I have't a clue...
I have no problems shifting the thing - it shifts like a truck transmission, it isn't a sports car and I think that's where some folks end up having problems.
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