General Info: GM Gearbox numbers
Posted: Thu Aug 13, 2009 10:27 pm
I posted this elsewhere and thought it might be useful here.
The type designation for a manual gearbox is divided into three groups of characters thus:
FM55 501 A12345
The three groups of characters are separated by spaces and contain various pieces of information about the gearbox as specified below.
The first group:
Pos. 1 - Drive F = Front-wheel drive
Pos. 2 - Type of gearbox
A = Automatic gearbox
C = ACS and manual gearbox
M = Manual gearbox
Pos. 3 - Number of forward speeds
Pos. 4 - Overall ratio in top gear (code, see table)
Code 0 / 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9
Gear
ratio 3.2 / 3.1 /3.0 / 2.9 / 2,8 / 2,7 / 2,6 / 2,5 / 2,4 / 2,3
The second group:
Pos. 5 - Engine/Car adaptation
5 = Manual gearbox adapted to engines B206I, B234I and B204L
6 = Manual gearbox adapted to engine B258I
7 = Automatic transmission adapted to B206I engine 8 = Automatic transmission adapted to B234I engine Pos. 6-7 - Development variant
The third group:
Pos. 8-13 - Serial number.
Manual gearboxes have a six character designation which starts with a letter which shows the line on which the gearbox was fitted. Each
number series consists of a five digit number.
The type designation for a manual gearbox is divided into three groups of characters thus:
FM55 501 A12345
The three groups of characters are separated by spaces and contain various pieces of information about the gearbox as specified below.
The first group:
Pos. 1 - Drive F = Front-wheel drive
Pos. 2 - Type of gearbox
A = Automatic gearbox
C = ACS and manual gearbox
M = Manual gearbox
Pos. 3 - Number of forward speeds
Pos. 4 - Overall ratio in top gear (code, see table)
Code 0 / 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9
Gear
ratio 3.2 / 3.1 /3.0 / 2.9 / 2,8 / 2,7 / 2,6 / 2,5 / 2,4 / 2,3
The second group:
Pos. 5 - Engine/Car adaptation
5 = Manual gearbox adapted to engines B206I, B234I and B204L
6 = Manual gearbox adapted to engine B258I
7 = Automatic transmission adapted to B206I engine 8 = Automatic transmission adapted to B234I engine Pos. 6-7 - Development variant
The third group:
Pos. 8-13 - Serial number.
Manual gearboxes have a six character designation which starts with a letter which shows the line on which the gearbox was fitted. Each
number series consists of a five digit number.