Aisin AX15 Jeep Transmission
The AX15 transmission has always been a great transmission to handle the torque and horsepower of most V8 engines. The biggest problem now is the availability of new units. With the lack of availability of new NV3550s, we revisited the possibility of obtaining the Aisin Warner AX15 transmission and were successful.
Although the torque specifications are not listed for this transmission in any service manual, we are confident it's similar enough to the NV3550 for replacement and conversion applications. The NV3550 was the transmission that superseded the AX15, and Jeeps used the same engine with the same vehicle ratings. We currently offer the AX15 for sale with a 0.75 tip (matching the 1992-99 factory Jeep transmissions), a 23-spline output shaft and a 13-degree tail housing.
With the availability of AX15 transmissions, we can now offer some additional transmission retrofit applications. See below for an overview of potential Jeep AX15 transmission replacements and conversions, tips for the retrofit process and recommended hardware kits to assist with your AX-15 transmission swap. We also offer oil for this transmission under part #29-2341; this GL-4 oil is a direct replacement for the now obsolete GL-3 lubricant originally used. Call Advance Adapters at 800-350-2223 with questions about compatibility or fitment.
*Please allow at least two weeks for all transmission shipments.
Note: These AX15 transmissions feature a 13-degree tail housing rotation and are exact replacement transmissions for 1997-2000 Jeep TJ Wranglers. If you are installing this AX15 into a Jeep Cherokee XJ, the tail housing rotation will be wrong; the Cherokee's transmission has a 23-degree rotation tail housing. The rotation difference will lead to installation issues with the Cherokee NP231 transfer case shifter.
AX15 Direct Replacement
AX15 transmissions were used between 1988 to 1999 in Jeep vehicles plus some Dodges. Since most of these machines have a lot of mileage, a new AX15 makes sense as a direct retrofit. It is available with an internal and external release bearing design.
Retrofitting the AX5 with the AX15
This is a newer kit for all four-cylinder Jeeps from 1987 to 2002. The AX5 is considered a light-duty transmission compared to the AX15. Jeeps equipped with larger tires and lower gears in the axle and transfer case may find the weak link in the drivetrain is the stock transmission. You can now replace the AX5 with the AX15 to gain some drivetrain strength. The nice thing is that when you're ready to replace the four-cylinder engine with a larger V6 or V8, the AX15 is an ideal transmission for the power increase. See kits #712563 and 712564; this transmission swap will also require a new transfer case input gear with 23 splines.
Peugeot Five-speed Replacement
The AX15 is the same length as the Peugeot BA10/5 transmission. The kits we offer include a new input gear for either the New Process 231 or 207 transfer case. Due to vehicle variances, some applications may require transfer case linkage modifications. Kits include a new bellhousing, transfer case shifter linkage, a crossmember adapter mount to retain the stock Peugeot rubber mount, a slave cylinder kit and an input gear for your transfer case. See kits #27-3507AA and 27-3510AA.
Bronco Dana 20 Applications for the AX15
These transmissions are ideal transmission swaps for the early Broncos. The weight of these five-speeds is similar to the stock three- and four-speed transmissions. The overall size and length make it an ideal fit. The gearing of these AX15 five-speeds is as follows:
- 1st - 3.83:1
- 2nd - 2.33:1
- 3rd - 1.44:1
- 4th - 1.00:1
- 5th - 0.79:1
- Reverse - 4.76:1
Frequently Asked Questions
What vehicles did the AX15 come in?
The AX15 first appeared in mid-1988 on the Jeep Wrangler YJ, Cherokee XJ and Comanche MJ. From 1989-99, it was in all Jeep YJ, XJ and Wrangler TJ manual transmission vehicles plus five-speed manual Comanches. The AX15 also came in six-cylinder 1993 Grand Cherokee XJs and the first- and second-generation Dodge Dakota. It was mainly paired with the AMC 242 4.0 inline-six, AMC 258 4.2L inline-six and AMC 2.5L straight-four engines and an NP207 or NP231 transfer case. The 1988-93 AX-15 transmissions had an internal slave cylinder while the 1994-99 versions switched to a external cylinder.
How much power can an AX15 handle?
Original AX15 transmissions from donor vehicles can handle approximately 300 hp and 300 lb.-ft. of torque. A new AX15 transmission such as this one, on the other hand, is rated for 385 lb.-ft. of torque thanks to updated materials and manufacturing
What's the difference between the AX5 and AX15?
Performance-wise, the biggest difference is that the AX5 has slightly higher first-gear (3.92:1) and fifth-gear (0.85:1) ratios than the Jeep AX15 transmission. This makes the AX15 a little better for off-roading and towing because it can get off the line easier. Also, the AX5 has a 21-spline output and 14-spline input; the AX15 is 23 and 10 spline.
What are the main differences between the AX15 transmission and other manual transmissions like the NV3550 or TR-4050?
The Aisin AX15 is considered a fine transmission for medium-duty on-road and off-road applications. Its torque capacity is not as high as the TR-4050 and NV3550, meaning the transmission won’t perform as well when towing or if mated to a high-power engine. The Jeep AX15 transmission also does not have the extremely low first-gear ratio those units have, so it is not as useful for rock crawling.
What vehicles originally came with the AX15, and what are the common swaps or upgrades for off-road applications?
The AX15 was used by Jeep from 1988 to 1989 in vehicles that had an AMC 2.5L I4, 242 I6 or 258 I^ engine. This includes the Wrangler JY, Cherokee XJ, Comanche and 1997-2000 Wrangler TJ. Chrysler also used the AX15 in the 1994-95 Grand Cherokee and the Dodge Dakota. (Note the tail housing was different based on the vehicle.) The transmission can be swapped into other vehicles to replace a light-duty transmission; many DIYers use it to replace Jeep’s previous Peugeot BA150 five-speed. You can also upgrade the gears in the AX15 with a stronger set and/or a different ratio to improve off-road performance.
