The Aisin-Warner AX5 Transmission was a standard shift 5 speed transmission used in Jeeps between 1984 and 2006. It is a light-duty transmission that was typically paired with the AMC 2.5L I4 and the GM 2.8L V6 engines. Being a light-duty transmission, it is not suitable for use behind higher-power engines, even the 4.0L.
The AX4 is an AX5 with one less gear, and can be found in the XJ and MJ vehicles, equipped with the AMC 2.5L I4, GM 2.8L V6, and the 2.8L Turbo Diesel.
If you ever find yourself doing an engine swap on a Jeep, you should ensure your standard transmission is not an AX5 and replace it with something that can handle more power, such as the AX15. The AX5 transmission is not worth repairing or working on, and for any hard use of your Jeep it is recommended that you just swap the AX15 in as it is nearly a direct replacement.
The AX4/AX5 transmission is sensitive to GL lube that contains sulfur. Sulfur reacts with the brass parts in the transmission leading to premature failure. Mopar recommends 75W-90 API Grade GL-3 gear lubricant. GL-3 lubricant is discontinued, and can very rarely be found for purchase. Fortunately, these transmissions have been approved to run on Synthetic 10W-30 Motor Oil. Others recommend Redline MT90 as another safe option.
The correct level can be set by simply filling to the bottom edge of the fill plug hole.
More information about the AX5 can be found here.
Fluid Type and Capacity
|Lubricant Type||75W-90 GL3 or GL4|
10W-30 Motor Oil
|Capacity (2WD)||3.70 qts|
|Capacity (4WD)||3.49 qts|
Transfer Case Compatibility
The AX4/AX5 was attached to the New Process Model 231 transfer case. Due to transmission weakness, adapter plates do not exist or are hard to find.
The AX4/AX5 was compatible with the AMC 2.5L I4 and GM 2.8L V6.
AX15 and Transfer Case Swap Information
Contrary to popular belief, the AX15 will not easily swap into a Jeep with the AX4/5 transmission. The bellhousing bolt pattern is different. If you are looking to swap an AX15 behind an engine that currently has the AX4/5 you will need to use this kit from advanced adapters, along with a 1994 and up AX15 with external slave cylinders. You will retain your AX4/5 bellhousing and shifter housing.
The NP231 transfer case that came behind the AX4/5 used a 21 spline input gear, while the transfer case married to the AX15 accepts a 23 spline input. You will need to change out the input gear in your NP231 transfer case. If your transfer case was built between 1988 and 1994, you will need this gear. If it was built in 1995 and up, you will need this gear (when using this gear with the AX15, the input gear must be shortened).
Write-ups and Tutorials
To Be Completed