Manual Transmission

Understanding the Manual Transmission

Because of the way an internal combustion engine breathes, it can produce torque (or twisting force) only within a narrow speed range. Most overhead valve pushrod engines must turn at about 2500 rpm to produce their peak torque. Often by 4500 rpm, they are producing so little torque that continued increases in engine speed produce no power increases.

The torque peak on overhead camshaft engines is, generally, much higher, but much narrower.

The manual transmission and clutch are employed to vary the relationship between engine RPM and the speed of the wheels so that adequate power can be produced under all circumstances. The clutch allows engine torque to be applied to the transmission input shaft gradually, due to mechanical slippage. The vehicle can, consequently, be started smoothly from a full stop.

The transmission changes the ratio between the rotating speeds of the engine and the wheels by the use of gears. 4-speed or 5-speed transmissions are most common. The lower gears allow full engine power to be applied to the rear wheels during acceleration at low speeds.

The clutch driveplate is a thin disc, the center of which is splined to the transmission input shaft. Both sides of the disc are covered with a layer of material which is similar to brake lining and which is capable of allowing slippage without roughness or excessive noise.

The clutch cover is bolted to the engine flywheel and incorporates a diaphragm spring which provides the pressure to engage the clutch. The cover also houses the pressure plate. When the clutch pedal is released, the driven disc is sandwiched between the pressure plate and the smooth surface of the flywheel, thus forcing the disc to turn at the same speed as the engine crankshaft.

The transmission contains a mainshaft which passes all the way through the transmission, from the clutch to the driveshaft. This shaft is separated at one point, so that front and rear portions can turn at different speeds.

Power is transmitted by a countershaft in the lower gears and reverse. The gears of the countershaft mesh with gears on the mainshaft, allowing power to be carried from one to the other. Countershaft gears are often integral with that shaft, while several of the mainshaft gears can either rotate independently of the shaft or be locked to it. Shifting from one gear to the next causes one of the gears to be freed from rotating with the shaft and locks another to it. Gears are locked and unlocked by internal dog clutches which slide between the center of the gear and the shaft. The forward gears usually employ synchronizers; friction members which smoothly bring gear and shaft to the same speed before the toothed dog clutches are engaged.

Shift Handle

REMOVAL & INSTALLATION

M5OD

Remove the shifter boot retaining screws and ...

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... lift the boot (1) from the transmission opening cover

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Remove the transmission opening cover retaining screws and remove the cover

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1. Disconnect the negative battery cable.
2. Remove the shifter boot retaining screws and lift the boot (1) from the transmission opening cover.
3. Remove the bolt (2) retaining the upper shift lever to the lower shift lever (3) and remove the upper shift lever.
4. Unfasten the transmission opening cover retaining screws and remove the cover.
5. Remove the lower shift lever boot.

To install:

6. Install lower shifter boot and transmission opening cover. Tighten the cover retaining bolts.
7. Install the upper shift lever to the lower lever and install the retaining bolt. Tighten 20-29 ft. lbs. (27-40 Nm).
8. Place the shifter boot into position and tighten the retaining screws.
9. Connect the negative battery cable.

ZF

Remove the shifter boot retaining screws and slide the boot up the shift lever shaft

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Remove the shift lever retaining bolts and remove the shift lever and shifter boot from the stub shaft

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Remove the shifter stub shaft from the transmission by removing the six retaining bolts

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1. Disconnect the negative battery cable.
2. Remove the carpet or floor mats.
3. Remove the shifter boot retaining screws and slide the boot up the shift lever shaft.
4. Remove the shift lever retaining bolts.
5. Remove the shift lever and shifter boot from the stub shaft.
6. Remove the shifter stub shaft from the transmission by unfastening the six retaining bolts and removing the stub shaft and shifter cover. Detach the electrical connector from the shifter cover and remove the assembly.

To install:

7. The installation is the reverse of the removal.

Back-up Light Switch

REMOVAL & INSTALLATION

Typical back-up lamp switch location—mounted on the transmission

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1. Disconnect the negative battery cable.
2. Raise and safely support the vehicle securely on jackstands.
3. Detach the connector for the back-up light switch.
4. Using a suitable size wrench or socket, remove the back-up light switch.

To install:

5. Installation is the reverse of the removal procedure.
6. Tighten the switch to 18-26 ft. lbs. (25-35 Nm) on the M5OD and 15 ft. lbs. (20 Nm) on ZF models.

Extension Housing Seal (in-Vehicle)

REMOVAL & INSTALLATION

2WD Models

Removing the extension housing seal

Always replace the old seal with a new one

Using a special tool and mallet, install the new seal

The extension seal on 2WD drive vehicles is located at the rear of the transmission case.

1. Raise and support the vehicle safely.
2. Drain the transmission of lubricant.
3. Matchmark the driveshaft to the yoke for reassembly and remove the driveshaft.
4. Remove the old seal using a seal puller or appropriate prytool.

To install:

5. Install a new seal, coated with sealing compound, using an appropriate seal installation tool.
6. Install the driveshaft, making certain to align the matchmark.
7. Fill the transmission to the level of the fill plug hole.
8. Install the plug and lower the vehicle.

4WD Models

The extension seal on 4WD drive vehicles is located at the rear of the transfer case.

Manual Transmission Assembly

REMOVAL & INSTALLATION

M5OD

Remove the retaining bolt from the transmission electrical harness connector and separate the harness

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Remove the nuts retaining the transmission support insulator (mount) to the crossmember

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Remove the 2 heat shield retaining bolts

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Remove the nuts and bolts retaining the crossmember to the frame side rails and remove the crossmember

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Remove the nut retaining the fuel line bracket to the transmission housing

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On 4.2L equipped models, remove the oil pan-to-transmission bolts

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Transmission-to-engine bolt locations—4.2L engine

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Transmission-to-engine bolt locations—4.6L and 5.4L engines

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This type of transmission is found on F-150, F-250 and Expedition models.

1. Disconnect the negative battery cable.
2. Remove the retaining bolt from the transmission electrical harness connector and separate the harness.
3. Place the transmission in NEUTRAL.
4. Remove the shift lever assembly.
5. Raise and safely support the vehicle.
6. Support the vehicle with jack stands.
7. Remove the driveshaft.
8. Disconnect the clutch hydraulic line from the slave cylinder using Clutch Coupling Tool T88T-70522-A, or equivalent. Cap the end of the tube and slave cylinder to prevent the entry of dirt, moisture or other contaminants into the hydraulic clutch system.
9. Disconnect the starter motor electrical connectors. Remove 2 starter motor retaining bolts and remove the starter motor.
10. On 4x4 vehicles, remove the transfer case assembly.
11. Disconnect heated oxygen sensor (HO₂S) electrical harness connectors.
12. Place a suitable transmission jack under transmission and secure with a strap or chain.
13. Remove the nuts retaining the transmission support insulator (mount) to the crossmember.
14. Remove the 2 heat shield retaining bolts.
15. Remove the nuts and bolts retaining the crossmember to the frame side rails and remove the crossmember.
16. Remove the 2 nuts retaining the exhaust pipe bracket and remove the bracket.
17. Remove the nut retaining the fuel line bracket to the transmission housing.
18. Remove the exhaust system bolts and lower the exhaust for transmission removal.
19. On 4.2L equipped models, remove the oil pan-to-transmission bolts.

If the transmission is to be removed from the vehicle for an extended period, support the rear of the engine with a safety stand and wood block, or equivalent.

20. Remove the transmission retaining bolts and bring the transmission rearward to separate the clutch housing from the dowel pins on the rear of the cylinder block. Slowly lower the transmission from the vehicle.

To install:

21. The extension housing seal should be replaced before installing the transmission. Remove the extension housing seal using Removal Tool T74P-77248-A, or equivalent.
22. Lubricate the inside diameter of the oil seal and install the seal into the extension housing using Installer Tool T61L-7657-A, or equivalent. Ensure that the extension housing seal drain hole faces downward.
23. Install 2 dowel pins into the lower clutch housing bolt holes. The dowel pins can be made by cutting the heads from 2 bolts but they must be long enough to be removed after the transmission is in place.
24. Place the transmission on a suitable transmission jack and secure with a strap or chain.
25. Slowly lift the transmission into place. Ensure that the input shaft engages the clutch disc spline and the pilot bearing in the flywheel.
26. Install the bolts retaining the clutch housing to the cylinder block. Tighten the bolts to 38 ft. lbs. (50 Nm). To avoid galvanic corrosion, only aluminum washers can be used to attach the housing to the engine.
27. On 4.2L equipped models, install the oil pan-to-transmission bolts. Tighten the bolts to 38 ft. lbs. (50 Nm).
28. Place the exhaust system in position and install the retaining bolts.
29. Place the fuel line bracket in position and install the retaining nut.
30. Place the exhaust bracket in position and install the retaining nuts.
31. Install the rear crossmember and install 6 crossmember-to-frame bolts. Tighten the bolts to 39-53 ft. lbs. (53-72 Nm).
32. Install the 2 heat shield retaining bolts.
33. Lower the transmission ensuring the rear transmission insulator studs are properly positioned. Install 2 retaining nuts and tighten to 64-81 ft. lbs. (87-110 Nm).
34. Remove the jack and connect the 2 heated oxygen sensors (HO₂S).
35. Install the starter motor and tighten the attaching bolts.
36. On 4x4 vehicles, install the transfer case.
37. Install the driveshaft to the rear axle flange and tighten the bolts.
38. Remove the cap from the hydraulic clutch tube. Install the tube and fitting in the slave cylinder, then install the clip retaining the tube and fitting to the slave cylinder.
39. Check the transmission and transfer case fluid level and fill with specified lubricate.
40. Remove the jack stands.
41. Lower the vehicle.
42. Install the shift lever and retaining bolt.
43. Place the rubber shift boot on the floor and install the retaining bolts.
44. Connect the negative battery cable.
45. Bleed the hydraulic clutch system.
46. Road test the vehicle and check for proper transmission operation.

ZF Series

This type of transmission is found on F-250HD/SD, F-350 and F-Super Duty models.

1. Place the transmission in neutral.
2. Remove the shifter from the vehicle. Refer to the procedure in this section.
3. On 7.3L diesel engine equipped models only, loosen the clamp on the turbocharger wastegate exhaust outlet.
4. Raise and support the vehicle safely.
5. Remove the starter.
6. On 7.3L diesel engine equipped models only:
   1. Remove the nuts retaining the exhaust extension pipe to the muffler assembly.
   2. Remove the engine charge exhaust pipe and extension pipe.
7. Place a drain pan under the case and drain the case through the drain plug.
8. Remove the driveshaft(s).
9. Disconnect the back-up lamp switch.
10. Remove the clutch slave cylinder.
11. On 4 wheel drive models, remove the skid plate from under the transfer case.
12. On 4-wheel drive models, remove the transfer case.
13. Remove the transmission rear insulator and lower retainer.
14. Unbolt and remove the crossmember.
15. On the 6-speed ZF transmission, disconnect the transmission cooling tubes
16. Remove the transmission-to-engine block bolts.
17. Roll the transmission rearward until the input shaft clears, lower the jack and remove the transmission.

To install:

18. Install 2 guide studs into the lower bolt holes.
19. Raise the transmission until the input shaft splines are aligned with the clutch disc splines. The clutch release bearing and hub must be properly positioned in the release lever fork.
20. Roll the transmission forward and into position on the front case.
21. Install the bolts and torque them to 39-53 ft. lbs. (53-72 Nm). Remove the guide studs and install and tighten the 2 remaining bolts.
22. On the 6-speed ZF transmission, connect the transmission cooling tubes
23. Install the crossmember and torque the bolts to 55 ft. lbs. (75 Nm).
24. Install the transmission rear insulator and lower retainer. Tighten the bolts to 60 ft. lbs. (81 Nm).
25. On 4-wheel drive models, install the transfer case and skid plate.
26. Install the slave cylinder.
27. Connect the back-up lamp switch.
28. Install the driveshaft(s).
29. Remove the transmission jack.
30. On 7.3L diesel engine equipped models only install the exhaust extension pipe to the muffler assembly.
31. Install the starter.
32. Fill the transmission.
33. Lower the vehicle.
34. Install the shifter.
35. On 7.3L diesel engine equipped models only, tighten the clamp on the turbocharger wastegate exhaust outlet.
36. Connect the negative battery cable.

Chilton® Automotive Information Systems. © 2004 Thomson Delmar Learning.