M32 Gearbox

M32 6 Speed manual transmission

Bearing failure on the M32 gearbox is very common.

Typically you will notice a whining noise when cruising on the motorway in 6th gear. The whining will come and go as you press and release the accelerator. When the bearings wear even more, the gearstick will begin to move as you press and release the clutch in first gear.

In our experience, just one bearing fails.

Failed bearing is at the top of the photo

Excessive play and loose rollers

The bearing becomes pitted due to metal fatigue

Replacement of this bearing will usually rectify the issues with gearstick movement and whining.

Background information on the M32 gearbox

The M32 is a 6-speed manual transmission. This manual transmission is an all-synchromesh 3-shaft transmission.

This 3-shaft transmission has the following advantages:

  • Compact construction
  • Improved smooth-running performance
  • Better shift quality
  • High torque transmission
  • Low weight

Structure of the manual transmission Location of the shafts The following cross-sectional diagram shows the location of the respective shafts in the M32 transmission, as per the 3-shaft principle.

Structure of the manual transmission

Location of the shafts

The following cross-sectional diagram shows the location of the respective shafts in the M32 transmission, as per the 3-shaft principle.

  1. Upper main shaft
  2. Input shaft
  3. Lower main shaft
  4. Differential gear

In this transmission angular cone bearings are used for all shafts. These bearings require a certain amount of play and pre-tension. The required amount of bearing play and pre-tension is achieved at the production stage by using shims under the angular cone bearing in the transmission housing.

Location of gearwheels

This diagram shows the location of the gearwheels on the respective shaft.

  1. Lower main shaft
  2. 1st gear gearwheel
  3. 2nd gear gearwheel
  4. 5th gear gearwheel
  5. 6th gear gearwheel
  6. Input shaft with 1st/2nd gear
  7. 3rd/5th gear gearwheel
  8. 6th gear gearwheel
  9. 4th gear gearwheel
  10. Upper main shaft
  11. 4th gear gearwheel
  12. Reverse gear gearwheel
  13. 3rd gear gearwheel

One particular advantage of this 3-shaft transmission is that on the input shaft, the 3rd gear gearwheel is also used for 5th gear.

Power flow in the individual gears.

The following diagrams show the flow of power in the individual gears.

Location of components in the M32 transmission

The following exploded diagram shows the location of the components in the M32 manual transmission. The components of the individual shafts will then be described.

  1. Axle shaft seal ring
  2. Guide sleeve – differential housing
  3. Differential housing
  4. Seal ring – axle shaft seal ring sealing flange
  5. Axle shaft seal ring sealing flange
  6. Axle shaft seal ring
  7. Shim
  8. Differential assembly
  9. Transmission housing
  10. Upper main shaft assembly
  11. Input shaft assembly
  12. Lower main shaft assembly
  13. Clutch bleed connector
  14. Fastening sleeve
  15. Reversing light switch
  16. Central release
  17. Pressure line
  18. Clutch housing
  19. Gearshift assembly
  20. Magnet
  21. Oil baffle plate

Location of components in upper main shaft assembly

  1. Fluid collector pipe
  2. Upper main shaft
  3. Roller bearing – upper main shaft
  4. Retaining ring
  5. Needle roller bearing – reverse gear
  6. Reverse gear gearwheel (driven)
  7. Reverse gear shift sleeve
  8. Synchro ring – reverse gear
  9. Thrust piece
  10. Synchroniser body
  11. Spacer
  12. Retaining ring
  13. 3rd gear gearwheel (driven)
  14. Needle roller bearing – 3rd gear gearwheel
  15. Intermediate ring
  16. Synchro ring
  17. 3rd/4th gear shift sleeve
  18. Thrust piece
  19. Synchroniser body
  20. Retaining ring
  21. Shim
  22. Roller bearing – main shaft
  23. Needle roller bearing – 4th gear gearwheel
  24. 4th gear gearwheel
  25. Intermediate ring
  26. Synchro ring
  27. 3rd/4th gear shift fork
  28. Gear shift shaft
  29. Reverse gear shift fork

Location of components in lower main shaft assembly

  1. Thrust piece
  2. Retaining ring
  3. 1st/2nd gear shift sleeve
  4. Outer synchro ring
  5. Intermediate ring
  6. Inner synchro ring
  7. 2nd gear gearwheel (driven)
  8. Needle roller bearing – 2nd gear gearwheel
  9. Locking ring
  10. Pressure piece
  11. 5th gear gearwheel (driven)
  12. Needle roller bearing – 2nd gear gearwheel
  13. Synchro ring
  14. Thrust piece
  15. Synchroniser body
  16. Retaining ring
  17. 5th/6th gear shift sleeve
  18. Synchro ring
  19. 6th gear gearwheel (driven)
  20. Needle roller bearing – 6th gear
  21. Roller bearing – main shaft
  22. Shim
  23. 5th/6th gear shift fork
  24. Gear shift shaft
  25. 1st/2nd gear shift fork
  26. Synchroniser body
  27. Outer synchro ring
  28. Intermediate ring
  29. Inner synchro ring
  30. 1st gear gearwheel (driven)
  31. Needle roller bearing – 1st gear gearwheel
  32. Retaining ring
  33. Roller bearing – main shaft
  34. Main shaft
  35. Fluid collector pipe

Location of components in input shaft assembly

  1. Input shaft seal ring
  2. Roller bearing
  3. Input shaft
  4. 1st gear gearwheel (driving)
  5. 2nd gear gearwheel (driving)
  6. Input shaft bolt
  7. Shim
  8. Input shaft bearing
  9. 6th gear gearwheel (driving)
  10. 4th gear gearwheel (driving)
  11. Spacer
  12. 3rd/5th gear gearwheel (driving)

Synchronisation

An improved synchronisation system, already fitted to the F40 manual transmission, is used on the M32 transmission. The previous sliding blocks and synchro springs have been dispensed with and have been replaced with thrust pieces.

Matched synchronisation systems are also used for the individual gears.

Two and three-cone synchronisation systems are used.

The synchronisation systems used for each respective gear will be shown in the following.

1st/2nd gear

The three-cone synchronisation system is used for these two gears.

  1. Inner synchro ring
  2. Intermediate ring
  3. Outer synchro ring
  4. Shift sleeve
  5. Synchroniser body
  6. Thrust pieces

3rd/4th gear

A two-cone synchronisation system is used for these two gears.

  1. Intermediate ring
  2. Synchro ring
  3. Shift sleeve
  4. Synchroniser body

5th/6th gear

A single-cone synchronisation system is used for these two gears.

  1. Synchro ring
  2. Shift sleeve
  3. Synchroniser body

Reverse gear

Like 5th/6th gear, reverse gear also features a single-cone synchronisation system.

Gearshifting

The M32 manual transmission also has a cable gearshift. The individual gears are selected by means of a central gearshift unit.

Mark for the M32 manual transmission

The mark for the M32 manual transmission consists of a bar code and a combination of numbers.

The letters and numbers located below the bar code have the following meanings:

  1. M32 Transmission type
  2. O "Opel" design
  3. FAM2 Engine family
  4. 3.941 Ratio
  5. C Wheel set
  6. XXXXXXXX Serial number
  7. NR Transmission code

Transmission fluid

The M32 manual transmission uses the same transmission fluid as the F13 / F17 / F17+ / F23 / F25 / F35 and F40 transmissions.

The transmission's fluid fill quantity is 2.4 litres.

Container size Catalogue number Part number
1 litre SAE 80 19 40 768 9 120 541
60 litres SAE 80 19 40 710 9 194 349

Technical data

The maximum input torque for the M32 manual transmission is 320 Nm.

The weight of the M32 manual transmission is approx. 41.5 kg without fluid.

The overall length of the transmission is 329.5 mm.

Transmission ratio

Engine Z 20 LEL
1st gear 3.818
2nd gear 2.053
3rd gear 1.302
4th gear 0.935
5th gear 0.744
6th gear 0.614
Reverse gear 3.727
Output ratio 3.94