Getrag F23 (M86/MG3) 5-Speed Manual Transmission
2005 Model Year Summary
- Synchronizer sleeve angle modified on first and second gears
- Synchronizer material on fifth and reverse gears changed to molybdenum
- Synchronizer sleeve angle modified on third and fourth gears
- New concentric slave cylinder design for Cobalt application
- Common fluid reservoir added to Vue application
FULL DESCRIPTIONS OF NEW OR CHANGED FEATURES
SYNCHRONIZER SLEEVE ANGLE MODIFIED ON FIRST AND SECOND GEARS
The synchronizer sleeve that slides to engage first and second gears has a new first angle to allow better cold-weather engagement of the gears.
SYNCHRONIZER MATERIAL ON FIFTH AND REVERSE GEARS CHANGED TO MOLYBDENUM
For a more positive feel and improved durability, the friction material on the synchronizer is changed from carbon to molybdenum.
SYNCHRONIZER SLEEVE ANGLE MODIFIED ON THIRD AND FOURTH GEARS
A running change due to be incorporated midway through the 2005 model year is a modification to the synchronizer sleeve angle to allow improved shiftability.
NEW CONCENTRIC SLAVE CYLINDER DESIGN FOR COBALT APPLICATION
The concentric slave cylinder, which hydraulically actuates the clutch pressure plate, was redesigned to match the engine configuration in the Cobalt application. Operation of the clutch is unchanged.
COMMON FLUID RESERVOIR ADDED TO VUE APPLICATION
The fluid reservoir for the clutch circuit is changed for the VUE application to the same design used by the ION application. This design uses a reservoir where brake and clutch fluid share the same reservoir body, although partitions inside the reservoir keep the fluid for each function separate.
LOW MAINTENANCE
The 5-speeds use DEXIII, the common fluid in GM automatic and some manual transmission applications. The 5-speeds are also in the process of being certified for a new DEXVI fluid. The fluid is certified for the life of the transaxle. In addition, the clutch is actuated hydraulically, and so wear is automatically compensated and no clutch adjustments are necessary.
OVERVIEW
The 5-Speed is a three-axis conventional transverse manual transaxle with fully synchronized reverse gear. It features compact packaging, broad low-torque applications, and reliable operation. The M86 was introduced for the 2000 model year.
The 5-speed has 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 aluminum 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 remains stable even under extreme heat.
Reverse gear is synchronized, which is a design advantage. That means the vehicle does not have to be completely stationary in order for reverse gear to be selected by the driver.
The specifications for the transaxle came mostly from Opel, which uses most of the production of the transaxle in Europe. Getrag builds the transaxle in Bari, Italy. The primary differences between the M86 and MG3 are the gearset ratios (see specifications page) and the clutch housing (also called bell housing) machining. The case of the M86 and MG3 are cast identically, but mounting bosses are drilled for different engine mounting studs.
