F25

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The F25 manual transmission was fitted to many vehicles in the European General Motors production line up including the Opel Calibra. It was a 5 speed transmission with the following configuration:

Clutch Diameter 9.0 inches
1st Gear Ratio 3.38:1
2nd Gear Ratio 1.76:1
3rd Gear Ratio 1.12:1
4th Gear Ratio 0.89:1
5th Gear Ratio 0.77:1
Reverse Gear Ratio 3.17:1
Final Drive Ratio 3.82:1

There have been many references to the numbering designation that Vauxhall elected to utilse for gearboxes, one of the more common arguments is that it refers to the lb.ft torque capacity of the gearbox, in this case being a 250 lb.ft torque limit. Other arguments include that it is simply related to the engine size (the F25 gearbox was often fitted to 2.5L engine vehicles).

This argument, that is engine size is the justification for the numbering could be disputed as the Opel Vectra B with the 2.6L V6 engine was infact fitted with an F23 transmission.

As an example the F25 transmission was fitted to the Opel Calibra 2.5L models (C25XE and X25XE engined models)