1. Manual Transmissions

2. Purpose To change the torque going to the drive wheels Needed to start vehicle from a stand still

3. Basic Theory Manually shifted Clutch disc rotates the input shaft Output shaft powers wheels

4. Transaxle A differential and transmission in the same housing Common in four wheel drive vehicles Manual or automatic transmissions

5. Parts Input shaft Gears Synchronizers Shift fork

6. Parts Gear shift lever Output shaft Transmission case

7. Input Shaft Driven by clutch Turns gears inside transmission

9. Transmission gears Provides a means of changing output torque and speed

11. Synchronizers Devices that help gears mesh into desired arrangement

12. Shift fork Unit for moving gears in and out of arrangement

14. Gear shift lever A lever that provides the driver with the ability to change the gear arrangement

15. Output Shaft Shaft that transfers power from the transmission to the wheels Transfers power to drive shaft in a rear wheel drive vehicle

17. Transmission Case Housing that encases transmission shafts, gears, and lubricant

18. Gear Ratio Definition: the number of rotations a drive gear has to turn before the driven gear turns once

19. Determining Gear Ratio Found by dividing the number of teeth on the driven gear by the number of teeth on the drive wheel

20. Gear Reduction A smaller gear drives a larger gear Increases torque and decreases the speed

22. Over Drive Gear A large gear drives a smaller gear Torque is decreased and speed is increased

23. Gear types There are two types of gears found in manual transmissions –Spur gears –Helical gears

24. Spur Gears Teeth cut parallel to center shaft Not used for drive gears Used for gears that have to slide in and mesh with other gears Noisy

26. Helical Gears Teeth cut out of parallel to drive shaft Used for constant drive components More efficient Quiet

28. Gear back lash Small clearance between meshing gears Allows lubricant to flow between high friction gears Allows gears to expand during operation

30. Lubricant Splash lubricant Gears fling lubricant around transmission Gear oil: 80W to 90W (always check owner’s manual)

31. Transmission shafts Input shaft Counter shaft Reverse idler shaft Output shaft

32. Input shaft (AKA clutch shaft) Transfers power from clutch to the counter shaft Splined on clutch side and a fixed gear on the transmission side Whenever clutch is turning the input shaft is turning

33. Counter shaft (AKA cluster gear shaft) Holds counter shaft gears into mesh with the input shaft gear Counter shaft does not turn

34. Reverse idler shaft Small shaft that supports idler gear Reverse idler gear meshes with gears on both the input shaft and the counter shaft

35. Output shaft (AKA Main shaft) Holds output gears and synchronizers Extends out of the transmission to power the drive wheels

36. Shift forks Sits around synchronizer sleeves Transfers movement from the gear shifter linkage to the synchronizers

37. Problems Grinding sounds when shifting –Worn gear change linkage –Clutch grabbing –Synchronizer gears grinding going into mesh

38. Problems Transmission noise –Roaring, rumbling, whirling sounds Low lubricant, metal contaminants

39. Problems Difficulty shifting –Problem with the linkage for the shifter mechanism –Clutch problems

40. Problems Jump out of gear –Worn clutch pilot bearing causes vibration and wobbling of the transmission input shaft. The vibration and wobbling shakes the synchronizers out of gear

41. Problems Locked in gear –Shifter assembly problems –Broken drive gear teeth, bits stuck in gears