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The F23 is a five-speed manual transmission manufactured by Getrag in Italy.[citation needed] It is designed for transverse engine applications, primarily by General Motors. It can handle torque inputs of over 230 newton-metres (170 lbf⋅ft).
The F23 has one roll pin, two gearsets on each of three parallel shafts – the input shaft, the output shaft, and the intermediate shaft. This three-shaft (also called three-axis) design results in a very short axial length for better packaging. There are three separate shift fork shafts, which hold three shift forks to activate the synchronizer rings for the two gearsets on each of the three gear shafts. The shift forks are activated by a cable system. The clutch release bearing is operated by a concentric slave cylinder that surrounds the input shaft in the clutch housing. A concentric slave cylinder allows more linear clutch feel than an external lever-actuated clutch and release bearing. The input shaft carries the 3rd and 4th gear synchronizer, the intermediate shaft carries the 1st and 2nd gear synchronizer, and the output shaft carries the 5th and reverse gear synchronizer. The aluminium case contains a conventional final drive gearset.
There are sintered bronze double-cone blocker rings on the synchronizers for 1st and 2nd gears, while 3rd and 4th gears use carbon fiber blocker rings, and 5th and Reverse gears use molybdenum on their synchronizers. Carbon and molybdenum are extremely durable friction surfaces that remain stable even under extreme heat.[1]
In the U.S. market, General Motors uses the F23 in two versions (with several application variations): the M86/M94 and MG3.
There is now an aftermarket source for limited slip differentials, of the helical-gear, torque-sensing / torque-biasing design.
It also has a following in the ecotec racing community for being able to handle 700 hp with an LSD insert and only costing about $200. It does not have the problems that plague the F-35 found in the SS, so it makes for a good transmission swap candidate.