Aisin AX5 Transmission Overview
First introduced in the 1987 Jeep Wrangler YJ and 1984 Jeep Cherokee XJ, the Aisin Warner AX5 is a five speed manual transmission that features a split case, and an overdrive fifth gear. It is very similar to the earlier 4-speed AX4 transmission, but obviously with an additional overdriven 5th gear.
The input shaft on the Jeep AX5 transmission was 1 inch in diameter and featured 14 splines, with a stickout length that measured 7 1/2 inches. The 21 spline output shaft was originally flush to the rear tail housing, but it stuck out 1/2 inch after 1997. This allowed it to mate the NP207 transfer case and NP231 transfer case.
Although it was used in well-known off-roaders like the Jeep Wrangler and Cherokee, it did suffer from a number of issues that made it undesirable for use in off-road focused vehicles.
OE AX5 5-speed Manual Transmission Applications
1984-2001 Jeep Cherokee XJ
1987-1992 Jeep Comanche MJ
1987-1995 Jeep Wrangler YJ
1996-2006 Jeep Wrangler TJ
1997-2006 Jeep Wrangler LJ
AX5 Technical Specs
Case: Cast aluminum with cast iron mid-plate
Input shaft: 14 spline | extends 7 1/2”
Output shaft: 21 spline
Length: 15 5/8” | 22 1/2” w/ bellhousing
AX5 Transmission Gear Ratios
1st = 3.92
2nd = 2.33
3rd = 1.44
4th = 1.00
5th = 0.85
R = 4.74
Common AX5 Transmission Problems
Initially, the Aisin AX5 transmission was fitted with a hydraulic throwout bearing. But leaking became a common AX5 problem, so that was replaced in 1994 with a more conventional external slave cylinder with a mechanical throwout bearing and clutch fork. In this configuration, the slave cylinder was mounted on the rear of the bellhousing.
Other AX5 transmission problems included a loss of fifth gear, and synchronizer problems.
Conclusion: AX5 Transmission
Due to the inherent weaknesses of the AX5 transmission, it’s common for owners to either install a completely remanufactured AX5 transmission, or swap it for a sturdier AX15 transmission.