AX15 4.31:1 Low First Gear Conversion Q&A

NovakConversions

NovakConversions

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Lot's of questions about this in another forum 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!
 
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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
 
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