D. AX4 & AX5 Jeep transmission

 AX4 & AX5

The AX5 transmission was a manual 5 speed transmission manufactured by the Aisin Corporation of Japan.  The AX5 was predominately used in the Jeep Wrangler and early XJ Cherokees. The transmission was first introduced behind the 2.8 V6 Cherokee as early as 1984. It was later utilized behind the AMC 150 (2.5L) 4cyl engine in the Wrangler from 1987 to 2002. The AX5 is considered light duty by most standards.

 

The AX5 transmission case is cast aluminum featuring a cast-iron middle-adapter plate which separate the front and rear sections of the transmission. The shifter is contained in the rear section of the transmission and is retained by 4 bolts.  The transmission case has numerous re-enforcement ribbing and features the shifter in the rear quarter of the assembly. The AX5 has a 21 spline output shaft for mating to the NP207 and NP231 transfer cases. Early model transmissions have the output shafts with a flush stick out in relation to the rear tailhousing. In 1997 the output shaft length switched to a ½” positive stick out past the tailhousing.

  The early model AX5 utilized an internal hydraulic throw out bearing assembly up through 1993 vehicles. Many Jeep owners experienced leaking problems with this assembly. In 1994, an external conventional style slave cylinder was introduced, where a mechanical style clutch fork and throw-out bearing were used. The slave cylinder was mounted on the backside of the bellhousing and parallel to the transmission. The transmission input shaft is 1”-14 spline with a stickout length of 7-1/2”. The pilot tip is .590”. The AX5 transmission case measures 15-5/8" in length with a 6-7/8” tailhousing section. The overall length of the transmission with bellhousing is 22.5”

  The AX5 transmission is often misidentified by individuals searching salvage yards. The transmission is directly related to other common transmissions like the 6cyl Wrangler AX15 and the Toyota Truck G52, W58 and R151. These transmissions were also manufactured by the Aisin Corporation. An inspection of the input shaft spline count can quickly identify the model of each transmission. It should also be noted that Jeep did offer a 4 speed version of the AX5 referred to as the AX4.

  The strength of the AX5 transmission has often been debated.     AX5 tranny  

The AX5 transmission was clearly designed for smaller horsepower motors. The overall longevity of the AX5 has mixed results, not only behind the factory 4cyl engines but behind engine conversions as well. Many factors besides horse power can result in the early demise of a transmission. Some of these factors include: vehicle weight, tire size, maintenance and driving style. Over the years, we have witnessed some drivers who have managed to kill numerous AX5 transmissions behind the factory 4cyl.  We also have a large AX5 customer base with successful years behind transplanted engines including V6 and mild V8s. Advance Adapters offers an extensive amount of engine and transmission options for the 4cyl Wrangler owners. We do however stress that proper judgment should be practiced when planning any type of conversion.

 

The overall transmission case length is 22.500", 15.625" case. The output shaft of these transmissions are a flush 21 spline in vehicles up to 1996, and then switched to a 1/2" stick out past the tailhousing in 1997 & newer Jeeps. They are normally found coupled to an AMC 4 cylinder engine and had either an internal or external slave cylinder.  The conversion bellhousing we manufacture requires a new slave cylinder, P/N 716213, which is mounted externally. The bellhousing indexes to the transmission case using a dowel pin alignment. The input shaft on the AX5 is 1"-14 spline, so all conversions will require the use of a special 10-1/2" clutch disc, P/N 716104.  The input shaft pilot tip diameter is .590", which is the same as a stock Chevy transmission.

 

We offer kits for the GM V6 or V8 to the AX4/5 transmission PN712565 

 

Ww also offer AX15 upgrades for the AX4/5 under PN27-AX15:

JEEP AX15 replacing the AX5: Tired of replacing your worn out AX5 transmission with another AX5? We have a solution to your dilemma. The AX15 transmission has long been touted as a good, reliable 5 speed transmission. We now offer a kit that will allow you the opportunity to upgrade rather than replace. This kit is designed to fit the 1995 & newer AX15 transmission. Earlier model transmissions can be used, but a stock pilot bushing with a .590" I.D. is required. This kit allows you to replace the light duty AX5 transmission with the stronger AX15 transmission. The 4 cylinder Jeeps are a popular vehicle for installing lift kits and using larger tires. Along with larger tires comes more wear and tear on the stock drivetrain components. 

PN712563 - Jeep AX15 replacing Jeep AX5 external slave

PN712564 - Jeep AX15 replacing Jeep AX5 internal slave 

The AX15 is approximately 2" longer than the AX5, so count on doing driveshaft modifications. We recommend that the stock flywheel be removed and resurfaced at a machine shop. A new clutch disc and release bearing has been provided in the kit. A new pressure plate is also recommended before installing your new transmission. This new pressure plate can be ordered under P/N CF361914.

Before disposing of the old AX5 transmission, you will need to retain the shifter housing from that transmission. You will also be using the stock 4 cylinder bellhousing, the stock release arm, and crossmember mount. 

The transfer case must have a new input gear installed to fit to the AX15 transmission. If retaining the NP231 transfer case, we highly recommend a fixed yoke kit be installed during this transmission swap because the new transmission is longer. This will allow for a new, longer rear drive shaft. The Atlas 2 speed or 4 speed transfer case is also an excellent upgrade for your Jeep, and this would be the perfect time to do this swap.

 

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