AX-15 vs NV4500

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Thejeepdude

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I bought an NV4500 trans with output shaft and Centerforce clutch from a buddy with same Atlas II and jeep setup as me. It's been in my garage for 20 years and I asked a local shop what they charge to install. They said money better spent relpacing
4.56 gears with 5.13s and keep AX15. This sounded like BS to me. How does AX15 compare to NV4500?
 
Stock 4.0? Tire size?

The shop is not incorrect that lower axle ratios take load off of the transmission. Meaning if you have a large tire, then abuse on the transmission would be lessened by going from 4.56 to 5.13.

Personally, under 4.0 power and pretty much any tire size within reason, the AX15 is fine. You need a pretty powerful engine to require NV4500 strength and the 4.0 isn't it.
 
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jjvw said:
Isn't the 4500 quite a bit taller than the ax15?
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Significantly. If I recall, past writeups I saw included building a fabricated box that bolted down on top of the trans tunnel to cover it up. They had the transmission protruding through the tunnel opening and the box was to cover the protrusion. Pretty ugly.
 
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I imagine no shop would want to install the 4500 unless they were doing them all the time and knew exactly what to do. The clutch fork operation does not bolt on, the transfer case input gear has to be changed, the transmission case is huge and clearance has to be made.....

Lastly, it's just not really a great option for the 4.0 anyways. It has a tall power sucking OD, and it's basically a 4 speed with a granny 1st so the gear splits are pretty far apart from 2-5. Unless it's just a crawler Jeep, I'd rather the AX15 for a better general purpose.
 
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machoheadgames said:
I imagine no shop would want to install the 4500 unless they were doing them all the time and knew exactly what to do. The clutch fork operation does not bolt on, the transfer case input gear has to be changed, the transmission case is huge and clearance has to be made.....

Lastly, it's just not really a great option for the 4.0 anyways. It has a tall power sucking OD, and it's basically a 4 speed with a granny 1st so the gear splits are pretty far apart from 2-5. Unless it's just a crawler Jeep, I'd rather the AX15 for a better general purpose.
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This ^
A shop could go down the rabbit hole making the 4500 work. Too much time fabbing , and modifying stuff. Regearing two axles is straight forward and profitable for the shop.
 
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machoheadgames said:
Stock 4.0? Tire size?































































































































































































































































The shop is not incorrect that lower axle ratios take load off of the transmission. Meaning if you have a large tire, then abuse on the transmission would be lessened by going from 4.56 to 5.13.































































































































































































































































Personally, under 4.0 power and pretty much any tire size within reason, the AX15 is fine. You need a pretty powerful engine to require NV4500 strength and the 4.0 isn't it.















Stock 4.0? Tire size?















The shop is not incorrect that lower axle ratios take load off of the transmission. Meaning if you have a large tire, then abuse on the transmission would be lessened by going from 4.56 to 5.13.















Personally, under 4.0 pow
Click to expand...


machoheadgames said:
er and pretty much any tire size within reason, the AX15 is fine. You need a pretty powerful engine to require NV4500 strength and the 4.0 isn't it.







Stock 4.0? Tire size?







The shop is not incorrect that lower axle ratios take load off of the transmission. Meaning if you have a large tire, then abuse on the transmission would be lessened by going from 4.56 to 5.13.







Personally, under 4.0 power and pretty much any tire size within reason, the AX15 is fine. You need a pretty powerful engine to require NV4500 strength and the 4.0 isn't it.
Click to expand...
 
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machoheadgames said:
Stock 4.0? Tire size?



The shop is not incorrect that lower axle ratios take load off of the transmission. Meaning if you have a large tire, then abuse on the transmission would be lessened by going from 4.56 to 5.13.



Personally, under 4.0 power and pretty much any tire size within reason, the AX15 is fine. You need a pretty powerful engine to require NV4500 strength and the 4.0 isn't it.
Click to expand...
 
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Besides both being manual transmissions there is almost no comparison. The NV4500 is likely way overkill and isn't extremely enjoyable to drive. It is also much larger than an AX15. It is certainly a significantly stronger transmission, but is this necessary for you?
 
machoheadgames said:
Stock 4.0? Tire size?
Click to expand...

Borla headers and exhaust, Racing Cat, airraid, extended throttle body. Maxxis 37x12.50x15 Creepy Crawlers.
machoheadgames said:
The shop is not incorrect that lower axle ratios take load off of the transmission. Meaning if you have a large tire, then abuse on the transmission would be lessened by going from 4.56 to 5.13.


Personally, under 4.0 power and pretty much any tire size within reason, the AX15 is fine. You need a pretty powerful engine t require NV4500 strength and the 4.0 isn't it.
Click to expand...

machoheadgames said:
Stock 4.0? Tire size?

The shop is not incorrect that lower axle ratios take load off of the transmission. Meaning if you have a large tire, then abuse on the transmission would be lessened by going from 4.56 to 5.13.

Personally, under 4.0 power and pretty much any tire size within reason, the AX15 is fine. You need a pretty powerful engine to require NV4500 strength and the 4.0 isn't it.
Click to expand...
 
Thejeepdude said:
Borla headers and exhaust, Racing Cat, airraid, extended throttle body. Maxxis 37x12.50x15 Creepy Crawlers.
Click to expand...

That....is basically stock. I would absolutely go to 5.13 gears and leave the transmission alone. Really I'd rather more gear than that but I don't know what axles you're running. If you don't have stock axles then you could possibly go 5.38 which I would do that instead.
 
machoheadgames said:
That....is basically stock. I would absolutely go to 5.13 gears and leave the transmission alone. Really I'd rather more gear than that but I don't know what axles you're running. If you don't have stock axles then you could possibly go 5.38 which I would do that instead.
Click to expand...

Dana 44 front Dana 60 rear. I don't want to have to replace ARB and Detroit which I would likely have to do. Not sure of the range of gearing that the lockers I have supports. Also, I don't know how to setup gears but I can change out trans. It came off of a Jeep that was setup much the same as mine with originally an AX15 and has same Atlas II transfer case as mine. I broke 2 sets of 4.56s in the old Dana 44 rear before I upgraded to the 60. That was with 36x12.50 Swamper SXs. I really don't want to go with smaller gears. I guess I could put a Whipple on it for more power.

This isn't a Barbie Jeep. It has been on the hardest trails in the South - School Bus, lower 2, helicopter pad, guard rail in Tellico when you could go there, all the good trails in Moab, Monteagle, etc... and has the scars to prove it. That is why I bought such a strong trans. The stock clutch in the AX is also going and I felt I could kill two birds...

Thanks.
 
Shank said:
Besides both being manual transmissions there is almost no comparison. The NV4500 is likely way overkill and isn't extremely enjoyable to drive. It is also much larger than an AX15. It is certainly a significantly stronger transmission, but is this necessary for you?
Click to expand...

I just want to restore it to on road drivability and keep the bulletproof capability to go off road when I want. My Jeep has quite a lot of heavy duty upgrades - Dana 44 front Dana 60 rear, Atlas II, all kinds of armor, etc. I paid $1800 for the NV4500 20 years ago and it is just gathering dust in my garage.
 
Thejeepdude said:
Dana 44 front Dana 60 rear. I don't want to have to replace ARB and Detroit which I would likely have to do. Not sure of the range of gearing that the lockers I have supports. Also, I don't know how to setup gears but I can change out trans. It came off of a Jeep that was setup much the same as mine with originally an AX15 and has same Atlas II transfer case as mine. I broke 2 sets of 4.56s in the old Dana 44 rear before I upgraded to the 60. That was with 36x12.50 Swamper SXs. I really don't want to go with smaller gears. I guess I could put a Whipple on it for more power.

This isn't a Barbie Jeep. It has been on the hardest trails in the South - School Bus, lower 2, helicopter pad, guard rail in Tellico when you could go there, all the good trails in Moab, Monteagle, etc... and has the scars to prove it. That is why I bought such a strong trans. The stock clutch in the AX is also going and I felt I could kill two birds...

Thanks.
Click to expand...

Well, I dunno what part number ARB or Detroit you have, but most of the time 4.56 and 5.13 or 5.38 will run the same carrier.

What Dana 44 front do you have?

I can change out a trans, I understand the basics of gears but haven't done them. But the 4500 is going to be more than just changing out a trans. As it was pointed out earlier, there is no room for a 4500, the clutch fork and slave cylinder will have to be completely reworked, it will want to protrude into the tub, etc. If the setup came from the friend with the clutch and stuff figured out, then maybe it can work more easily, but there is still the clearance issue. Not sure how your friend made room for it in his Jeep.

Not sure how you're breaking gears but that isn't typical, even on 5.38s. If they're set up properly and the axle is sized appropriately, shouldn't ever be a problem. I don't think a Whipple will fix whatever you are looking to fix....what was the actual goal with all of this?

Not saying you have a barbie jeep. I will say, the Atlas II is actually helping your AX15 and clutch also. The lower the gearing in the transfer case, the less stress the engine and trans see.
 
machoheadgames said:
Well, I dunno what part number ARB or Detroit you have, but most of the time 4.56 and 5.13 or 5.38 will run the same carrier.

What Dana 44 front do you have?

I can change out a trans, I understand the basics of gears but haven't done them. But the 4500 is going to be more than just changing out a trans. As it was pointed out earlier, there is no room for a 4500, the clutch fork and slave cylinder will have to be completely reworked, it will want to protrude into the tub, etc. If the setup came from the friend with the clutch and stuff figured out, then maybe it can work more easily, but there is still the clearance issue. Not sure how your friend made room for it in his Jeep.

Not sure how you're breaking gears but that isn't typical, even on 5.38s. If they're set up properly and the axle is sized appropriately, shouldn't ever be a problem. I don't think a Whipple will fix whatever you are looking to fix....what was the actual goal with all of this?

Not saying you have a barbie jeep. I will say, the Atlas II is actually helping your AX15 and clutch also. The lower the gearing in the transfer case, the less stress the engine and trans see.
Click to expand...

The front isn't so much the issue. I had it built in 99 before everyone and their brother was selling them. I thought about changing out to a Dana 60 front from one of Tera or Currie but don't want to spend the $9k.

The gear setup is like magic - it seems quite a complicated process with the shimming and all. The Jeep shop I talked to quoted me about $1600 and I don't want to spend if I don't have to. If I have to then it is what it is. Yeah, I bought the whole setup as he replaced with a Turbo 400 automatic.

I live in a neighborhood in the mountains and I have to go back and forth between 2nd and 3rd. Need more power in 2 high for these roads. My V8 Jag and 7.4L Suburban take them all with ease. Maybe the gearing is a must if I don't have to change out lockers... I still want the Whipple tho.

Thanks Macho.
 
Thejeepdude said:
The front isn't so much the issue. I had it built in 99 before everyone and their brother was selling them. I thought about changing out to a Dana 60 front from one of Tera or Currie but don't want to spend the $9k.

The gear setup is like magic - it seems quite a complicated process with the shimming and all. The Jeep shop I talked to quoted me about $1600 and I don't want to spend if I don't have to. If I have to then it is what it is. Yeah, I bought the whole setup as he replaced with a Turbo 400 automatic.

I live in a neighborhood in the mountains and I have to go back and forth between 2nd and 3rd. Need more power in 2 high for these roads. My V8 Jag and 7.4L Suburban take them all with ease. Maybe the gearing is a must if I don't have to change out lockers... I still want the Whipple tho.

Thanks Macho.
Click to expand...

Makes sense. If wanting more power I'd definitely look into the 5.13 or 5.38 swap. 5.38 if you can do it with your axles and current lockers. 5.38 is a dramatic difference from 4.56. Use a good reputation gear shop if you do it, and look into revolution gears for the parts. Very few breakages, there are lots of Rubicon owners here on 35's with 5.38s on their D44s. Nothing but good results.

The whipple would be fun to add, but I'd do that after the fact. I had equivalent gearing as you with stock 3.55s and 31s. Same as 33/3.73, 35/4.10, 37/4.56. I definitely would not have wanted to drive that in the mountains.

I will add, if you are wanting more power.....the 4500 will be worse for that. The gear gaps are further apart. 1st is shorter but the rest of the gears 2-5 you're having to deal with gears being further apart which will make your issue even worse.
 
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machoheadgames said:
Makes sense. If wanting more power I'd definitely look into the 5.13 or 5.38 swap. 5.38 if you can do it with your axles and current lockers. 5.38 is a dramatic difference from 4.56. Use a good reputation gear shop if you do it and look into revolution gears for the parts. Very few breakages, there are lots of Rubicon owners here on 35's with 5.38s on their D44s. Nothing but good results.
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Yeah, I think I may have to do the 5.38s. Thanks much for your replies. I am beginning to think that is the way to go if the carriers will support. I will look into the revo gears. I think mine in the old Dana 44 were Genuine gear. I still have the old Dana 44 rear with a Detroit. Genuine will replace the bad ones since they have a lifetime warranty so I could replace before selling axle. I have been storing that thing around for 20 years.
 
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