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Hey guys,
Does anyone have experience swapping the NV3550 with a NSG370? My understanding is that it pretty much just bolts straight in, the splines and bolt patterns are the same so they mate up with the motor and transfer case. The only modifications you need to do is relocate the CPS, splice/relocate new plugs for the electricals, and shifter location is a bit different in cab so either do some cutting or buy newer trim pieces from the later TJs.

What im not sure about is if its the same transmission mount, clutch slave, clutch and everything else in the bellhousing, and if its the same overall length so it wont cause issues with the drive shafts. Im also not exactly sure on the best way to go about with the CPS senor.

I know a lot of people here arent too keen on the 6 speed, but im in desperate need of a new gearbox and this one is newer with half the amount of mileage at 2/3 of the cost of the 5 speeds i have been finding. It would also be nice to have the lower 1st gear for offroad, and i imagine if i ever decided to sell it (God forbid) that it would increase the resale value, especially since the gearbox has 1/2 the mileage and 5 years newer than the rest of the Jeep.

Any help or advise would be much appreciated, I just dont want an nasty surprises giving me additional expenses or keeping the Jeep of the road for longer.
 

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Don’t do it
That German POS six speed is less reliable has led torque rating and has almost no parts availability when it takes a dump
The rare parts that you can find are very very pricey
It also has an overly complex failure prone shifter assembly
The six speed is best used for yard art or a heavy door stop

No a low mileage manual tranny will not increase resale value as they don’t fail based on miles

Buy a brand new ax-15, it is a fine tranny and low cost and direct replacement no adaption of anything needed

The biggest issue with the six speed vs 5 speed swap is difference in flywheel/crank sensor/sensor location
Forcing those dumping the 6 for a 5 to get a pricey custom aftermarket bell or go to a crank sensor (aftermarket) on front of engine


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X2, The NSG370 is the worst transmission jeep has used since the BA10 stay away from it
 

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I must be the only one who likes my 6 speed. Redline MTL and a hurst shifter really changed my opinion on the NSG.
 

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No! Replace it with a new AX15 that you can get from Novak for $1,600. Much better option and a direct bolt-in.
 

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To my knowledge, mine was never rebuilt.
I will be approaching 215k miles soon.
No issues in the 2.5 years I have had it.
Shifts smooth. Rubicon with 4.1 gears runs great on the highway with 33" tires.
 

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NSG-370 has it's advantages, namely better mpg (not a consideration for most), also that the first gear is lower than in the typical 5 speed. People may do t case swaps or ring and pinion but probably not that many people will change their individual tranny gear ratios. People will always say to steer away from the NSG-370 for the reliability problems. I may be wrong here but all transmissions will probably eventually need some work done sooner or latter. It's better than the other chrysler products which see overhauls sometimes at 100k.

I’ve had AX-5, AX-15, NV3550 and currently NSG370.

Other than the sometimes funky 5-6 shift. I have no complaints with it
I feel the shift from first to second is funky, and I usually start off in second. Never had any issues with going from 5th to 6th. I've only driven about 3k miles on it so far, going from 144k to 147k.
 

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NSG-370 has it's advantages, namely better mpg (not a consideration for most), also that the first gear is lower than in the typical 5 speed. People may do t case swaps or ring and pinion but probably not that many people will change their individual tranny gear ratios. People will always say to steer away from the NSG-370 for the reliability problems. I may be wrong here but all transmissions will probably eventually need some work done sooner or latter. It's better than the other chrysler products which see overhauls sometimes at 100k.



I feel the shift from first to second is funky, and I usually start off in second. Never had any issues with going from 5th to 6th. I've only driven about 3k miles on it so far, going from 144k to 147k.
Better gas mileage HOW
The six speed has less overdrive than either TJ 4.0 five speed has
Just because you have more gears does not mean you have more overdrive

But once it fails you do stop
Burning gas


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Better gas mileage HOW
The six speed has less overdrive than either TJ 4.0 five speed has
Just because you have more gears does not mean you have more overdrive

But once it fails you do stop
Burning gas


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You are right actually, it doesn't get better mpg, I was mistaken.
NSG-370: 6th .838

NV3550: 5th .78
 

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Very minimal difference in the overdrive gears between transmissions. (side note: NSG ending up getting a 0.79 OD 6th gear in 2012+ JK)

There is a greater difference between first gears. NSG’s 4.46 is much lower than AX’s 3.83 and NV’s 4.01
 

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Of course on street driving that granny low is less than useful and off road 4wd low makes it also of marginal usefulness

If the TJ came 2wd with no transfer case low that six speed granny low would have been real useful

As it is with the 4.0 broad torque curve and having a 4wd low gear on transfer case the 5 spds win again

If you had a German 2wd truck/van like it was reportedly designed for maybe one could justify using the six POS to get a more granny low


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Good for repair shops and bad for owners





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I wouldn’t consider 4.46 a granny low. I think the NSG’s gearing is excellent. Durability has been sketchy but gear spacing is one thing they did right

(First got even steeper on JL, the manual has 5.13 and 4.71 for the auto)
 

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Someone recently posted multiple YouTube videos of the teardown and rebuild of the NSG. Looks like a pretty simple trans, but I can see with plastic bits on the shift mechanism why I have the dreaded reverse kick out problem. Other than that I like mine and wouldn't be afraid to tear it down based on those videos. But would most likely swap it of it came to that.
 
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