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Any benefit of the NSG370 over the NV3550?

JakeQ

Member
Supporting Member
May 12, 2019
47
Colorado Springs
Any benefit of the 2005-06 six speed over the NV3550? If this has been talked about I didn't find it. I suppose another question would be, if I buy an 04, would I get any perks from putting the six speed in it instead?
 

Steel City 06

TJ Enthusiast
Mar 12, 2019
691
Pittsburgh, PA
The gear ratio in the 6 speed are closer together, so there’s not a larger spread. The 1st and final gear are both deeper than a NV3550, which is a small advantage as somewhat less axle gearing is needed.
I have the 6 speed, but I wouldn’t bother swapping it into a 5 speed. I might consider an AX-15 swap if this NSG370 grenades.
 
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Chris

Administrator
Staff Member
Sep 28, 2015
37,147
Salem, Oregon
The optimal choice for manual transmissions is neither of those, it's an AX-15.

Take whichever one you get, but if you keep it long enough and the manual transmission needs to be replaced, the smart thing to do is replace it with an AX-15. They are tried and tested, easy to get brand new, easy to get parts for, and cheap (as far as transmissions are concerned).

AA sells brand new ones for $1500. For this reason most everyone who needs to replace their NSG370 or NV3550 replaces it with an AX-15.
 
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OP
JakeQ

JakeQ

Member
Supporting Member
May 12, 2019
47
Colorado Springs
The optimal choice for manual transmissions is neither of those, it's an AX-15.

Take whichever one you get, but if you keep it long enough and the manual transmission needs to be replaced, the smart thing to do is replace it with an AX-15. They are tried and tested, easy to get brand new, easy to get parts for, and cheap (as far as transmissions are concerned).

AA sells brand new ones for $1500. For this reason most everyone who needs to replace their NSG370 or NV3550 replaces it with an AX-15.
I don't know why I had not remembered the AX-15. On TFL they were at a shop getting the trans in their Comanche looked at and the guy even told them the best path wasn't to rebuild but to switch to an AX-15.
 
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Boinked

TJ Addict
Jul 7, 2018
2,538
Mesa,az
The six speed has the following gears

4.462.611.721.251.000.84

The 5 speed 3550 has these.

4.012.331.391.00.78

The 5 speed ax 15 has these.

3.83, 2.33, 1.44, 1.00, 0.79



The 6 speed has a better low crawl. But not as tall of an overdrive. But im not convinced a .05 difference would be noticed much.
 

Quigley

Member
Oct 20, 2018
70
Kingston, WA
Does AA give you the option of changing the first gear ratio of 3.83 to something deeper? A retro fit of the 4.46 gear would be nice for the ax 15 or nv3550.

Why no love for the nv3550? lol. I have 150,000 miles on mine with the stock clutch and still shifts like new. In fact I'm only doing the clutch this summer as maintenance item since I'll be doing the SYE anyway. The problem is when people running the wrong fluids in it.
 
OP
JakeQ

JakeQ

Member
Supporting Member
May 12, 2019
47
Colorado Springs
Does AA give you the option of changing the first gear ratio of 3.83 to something deeper? A retro fit of the 4.46 gear would be nice for the ax 15 or nv3550.

Why no love for the nv3550? lol. I have 150,000 miles on mine with the stock clutch and still shifts like new. In fact I'm only doing the clutch this summer as maintenance item since I'll be doing the SYE anyway. The problem is when people running the wrong fluids in it.
I have this irrational fondness for driving great distances instead of taking a plane and renting a vehicle. My soon to be ex JL does this flawlessly, its 14 years newer. A TJ will be an X factor and a beast I'm still trying to learn about. I want to set it up for success. I want to still get into the back county, but still drive 1500 miles in one direction and back again. I have no doubt in my mind a TJ can still do these things.
 

Steel City 06

TJ Enthusiast
Mar 12, 2019
691
Pittsburgh, PA
The difference in OD between the NSG370 and NV3550 is about the same difference as between 4.56 and 4.88 gears.
In fact:

NSG370 and 4.56s:
0.84 OD X 4.56 gears = 3.83 drive ratio

NV3550 and 4.88s:
.78 OD X 4.88 gears = 3.80 drive ratio

AX-15 and 4.88s:
.79 OD X 4.88 gears = 3.86 drive ratio

NSG370 and 4.88s:
.84 OD X 4.88 gears = 4.10 drive ratio

There’s about an 8% difference in the OD ratios between the NSG370 and NV3550. So not significant, but noticeable
 
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Chris

Administrator
Staff Member
Sep 28, 2015
37,147
Salem, Oregon
I don't know why I had not remembered the AX-15. On TFL they were at a shop getting the trans in their Comanche looked at and the guy even told them the best path wasn't to rebuild but to switch to an AX-15.
Yep, that's always the best path. The AX-15 is so widely used that parts are available for it everywhere, they're much cheaper, and a brand new one can be had for a lot less than the other two transmissions that came in the later model TJs.
 

astjp2

TJ Addict
Aug 22, 2018
1,661
Utah and Alaska
If I have to pull my nsg in the LJ, it will get a 727 torqueflight and a cps relocation kit. Then I dont have to worry about electronic solenoids or overdrive problems or the PCM shitting the bed. Good for 1000 horsepower and the atlas will bolt right onto it. I just need to get a 32RH shifter/linkage/kickdown/cooler lines from a 90's TJ. Tim
 
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