BMW Cars 1999-06



The automatic transmission number is on a label affixed to the side of the casing. The label is located between the shift lever and bracket.

A letter code is found on the transmission case either on the center bottom of the transmission, the lower clutch bell housing or on a sticker on the side of the transmission extension. Using this letter code in conjunction with the BMW parts information for the vehicle, the transmission model can be determined.

The transmission coding method has been changed and the following are examples of old versus new numbers:

Old: 5HP 18-New: A5S 310Z
Old: THM R1-New: A4S 310R
Old: THM R1 D*-New: A4S 270R
Old: JATCO RLA-New: A5S 300J

The code is broken down as follows, using A5S 310Z as an example:

First character: A designates automatic
Second character: Number of gears
Third character: S: Overdrive, D: Direct gear
Fourth-Sixth: Transmission torque input
Seventh: Manufacturer, Z: ZF, R: Hydra-Matic (GM) Strasbourg (HMS), J: JATCO

A code letter combination may follow the last character for manufacturing variances and a D* indicates a diesel version which also uses a different rear axle ratio.

The code letter combination may be added to the transmission for clarification purposes, such as model year or production run changes. The following are typical code letter combinations that may be found on the transmission:

A K D: This is a code letter combination indicating a new unit
T A K D: This is a code letter combination indicating an exchange or remanufactured unit

A variety of transmissions are used, usage being determined by the chassis and engine combination. By chassis and engine, this is a general application overview:

E30 models:

M20 engine: 4HP 22
M42 engine: 4HP 22

E36 models:

M42 engine: A4S 310 R
M44 engine: A4S 270 R
1992-95 M50 engine: A4S 310 R
1996-98 S50 engine: A5S 310 Z
1996-98 (except 323 models), M52 engine: A4S 270 R
1998 323 models, M52 engine: A4S 310 R
1996-98 S52 engine: A5S 310 Z