AX15 4.31:1 Low First Gear Conversion Q&A

[NovakConversions]

Lot's of questions about this in my recap post so I wanted to start this Q&A thread.

Here is the conversion; https://www.novak-adapt.com/catalog/transmission/transmission-parts/ax15-low-first-gear.html

YES! It is retrofittable to existing transmissions. Note: very early AX15's had a nut on the shaft where there is now a snap ring. So the early version will need an additional snap ring along with this kit.

I personally would recommend at a minimum doing a bearing set while you do this conversion, just for good insurance.

Please post any questions you have!

 

[speeding_infraction]

Awesome. Definitely adding this to my list of stuff to do if the clutch ever gives up

 

[NovakConversions]

The Jeep AX15 is a proven, durable transmission, but in many builds—especially heavier rigs, larger tires, towing setups, and technical off-road applications—the factory 3.83:1 first gear can feel tall. This new gear set lowers first gear to 4.31:1, delivering improved torque multiplication and noticeably better control at low speeds.

What This Upgrade Delivers​

• Lower first gear: 4.31:1 vs. the stock 3.83:1
• Improved crawl ratio for rock crawling and technical terrain
• Smoother launches with less clutch slip, especially on inclines
• Reduced clutch wear in heavy, high-load applications
• Better throttle modulation at slow speeds

This is not a band-aid or external add-on—it’s a true internal gearing change designed to integrate cleanly into the AX15 when installed during a rebuild or overhaul. The result is a transmission that feels more controlled, more confident, and better matched to modern tire sizes and vehicle weights.

Ideal Applications​

• Rock crawling and technical off-road driving
• Overland and expedition builds
• Towing and utility use
• Heavier Jeeps or rigs running larger-than-stock tires

Availability​

The AX15 4.31:1 Low First Gear Conversion is currently available for pre-order.
Estimated ship date is April 2026.

If you’re planning an AX15 rebuild this winter or spring, this is an ideal time to plan ahead and incorporate a lower first gear into your build.

We’ll be sharing more details as production progresses. In the meantime, feel free to post questions below or reach out to Novak directly if you’d like help determining whether this upgrade makes sense for your specific application.

— Novak Conversions

 

[SkylinesSuck]

I picked up an NP241 to solve exactly the thing this would. My highway gearing is perfect with 4.10's on 33's and a stroker. My crawl ratio sucks bad though. I wonder if this would be a better option to installing the 241. I'll be keeping my eye on this!

 

[tnjeepguy]

I wonder if this would be a better option to installing the 241

no

Crawl ratio:

AX15, 231, 4.1 = 42.7
AX15+, 231, 4.1 = 48.1
AX15, 241, 4.1 = 62.8

AX15, 241, 4.1 = 38.2 (second gear, nearly what you have now in first gear)

 

[tnjeepguy]

Definitely adding this to my list of stuff to do if the clutch ever gives up

Big difference in changing a clutch and complete rebuild of an AX15.

 

[speeding_infraction]

Big difference in changing a clutch and complete rebuild of an AX15.

That's on me for not reading. I wasn't aware the whole thing had to come apart to put that in. Good to know

 

[sierradmax]

Could the 4.3:1 be installed in a new or rebuilt AX-15 from Novak? Would it be an add-on cost factor?

 

[NovakConversions]

Could the 4.3:1 be installed in a new or rebuilt AX-15 from Novak? Would it be an add-on cost factor?

We wouldn't do it in a new one. It just doesn't make sense to open up a new one, voiding the factory warranty, to do this when the rebuilt ones are readily available.

On a rebuilt, yes we will have that option. I don't know price point on that yet.