Ford 4F50N

Transmission general data

The 4-speed automatic transmission AX4N was designed in 1994. It is the modification of its predecessor AX4S, which is in turn the modification of the AOD-E transmission.This transmission was not very popular and since 2004 it had been frequently replaced by German CVT CFT30 and the 6-speed transmission AF21 (TF-81SC) until 2007 when Mazda produced the 6- speed 6F50, and later (2009) - the enhanced 6F55.

Technical issues and repair guidelines

The most popular spare parts rebuilding of this transmission are the following: repair kit of gaskets and seals (Overhaul kit). For all transmissions of this family installed on old cars, it is recommended to change ATF (Mercon V - Dexron-IV) with the filter each year after operation in hot summer time. It is required to check the ATF state for transparency. In many cases, problems of the AX4N are related to inconveniences in gears shifting caused by shortcomings of the valve body design, which gets clogged by friction dust.

Many specialists assume that the main reason of ATF contamination is the torque converter. The torque converter overheats ATF and facilitates to rapid oil contamination by friction wear debris, which quickly damage the valve body material. The manufacturer recommends installation of an additional transmission radiator.

Spare parts of the AX4N are sensitive to extreme operating conditions and as a result it leads to fast wear-out of all wearing elements, including brake bands Rear -Coast and O.D. - Overdrive, rubber-covered pistons. In the course of the transmission reassembly, it is recommended to check properly all rubber elements for elasticity of the rubber protection shield. The first compenents to get burnt are friction elments of the Direct package, and later Forward package. Other friction components wear out more rarely and often left untouched till the next overhaul.