Getrag F23 transmission

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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 up to 230 newton metres (170 lbf·ft).[citation needed]

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.

Gear ratios[edit]

M86/M94[edit]

Regular Production Option (RPO) code M86 and M94 is rated for lighter vehicles with a maximum gross vehicle weight rating (GVWR) of 1,857 kilograms (4,094 lb).[1]

Applications
Final Drive 1 2 3 4 5 R
3.94 3.58 2.02 1.35 0.98 0.69 3.31
Final Drive 1 2 3 4 5 R
3.84 3.58 2.02 1.35 0.98 0.69 3.31
Final Drive 1 2 3 4 5 R
4.17 3.58 2.02 1.35 0.98 0.69 3.31

MG3[edit]

RPO code MG3 is rated for heavier vehicles with a maximum GVWR of 2,030 kilograms (4,475 lb).[citation needed]

Applications
Final Drive 1 2 3 4 5 R
4.41 3.58 2.02 1.35 0.98 0.81 3.31

Mechanical Faults[edit]

Rattling / Grinding[edit]

On January 28, 2002, General Motors released a Technical Service Bulletin (TSB #02-07-29-001) addressing a "Grinding/Rattle Type Noise Coming From Transmission". The TSB was intended for the following GM vehicles equipped with the GM Quad 4 (RPO LD9) Engine and Getrag M86/M94 5-Speed Transmissions:

The bulletin continued to explain that there are actually two distinguishable noises which have two very different remedies.

There are two separate noises. Follow the diagnostic procedures listed below to determine which noise

the vehicle has and perform the outlined repair.

  • Noise 1: This is a very distinct noise that is usually much louder than the second noise that can be associated with

this transmission. If the vehicle is not making any noise when trying to verify the condition, it can be induced by making several tight left hand circles with the vehicle at normal operating temperature. Making a sharp right hand turn will usually stop the noise. While the noise is occurring, in order to distinguish between the two noises, you can press lightly on the clutch pedal without releasing the clutch and the noise will NOT go away or change. As a second diagnostic aid, while the vehicle is making the noise, shift to third gear and the noise will stop.

  • Noise 2: This noise, commonly referred to as gear rattle, can be induced by lugging the engine in any gear, but is

usually most noticeable in first or second gear. While the noise is occurring, if you press lightly on the clutch pedal without releasing the clutch, the noise will be reduced or eliminated.

General Motors provided a fix for "Noise #1" but stated that "Noise #2" was a characteristic of any car equipped with a manual transmission and that a similar noise could be repeated by lugging the engine. The remedy for "Noise #1" was to overfill the transmission with Saturn Manual Transmission Lubricant from the stock 1.8 quarts to 2.6 quarts. Although this seemed to work for many customers, many other complaints still surfaced and in 2003 General Motors released another TSB urging customers that still have the rattling noise in their transmissions should bring their vehicles in to their nearest General Motors affiliated dealer for a more complex fix.[citation needed] This time, GM Technicians had concluded that gears one and two required additional thrust loads and proceeded to install a wave washer between the blocking ring and speed gears for gears three and four. This indeed fixed the rattle issue once and for all, but has more recently been lamented in many online communities as causing a bigger problem than it solves, as many customers that received this fix reported third and fourth gears grinding from time to time while shifting[citation needed]. Afterwards, many owners of these vehicles have concluded that leaving the transmission alone was for the best, as the rattling noise has been proven to be harmless.[citation needed]

References[edit]