Section 9.5
Tachometer Drive

The Series 60 engine can be configured with or without a mechanical tachometer drive. A camshaft drive gear access cover mounted to the gear case cover and a slotted head camshaft bolt must be used with the mechanical tachometer drive option. See Figure "Tachometer Drive and Related Parts" .‪

Figure 1. Tachometer Drive and Related Parts

The tachometer drive is driven off the head of the camshaft drive gear retaining bolt, which must be of the slotted configuration, and mates with the blade of the tachometer drive unit. The tachometer drive unit is driven at half crankshaft speed. A tachometer drive adaptor is attached to the drive. See Figure "Tachometer Drive Adaptor" .‪

Figure 2. Tachometer Drive Adaptor

A grease fitting on the tachometer drive adaptor is supplied for lubrication. The tachometer drive adaptor should be greased any time the vehicle chassis is lubricated.‪

Section 9.5.1
Repair or Replacement of Tachometer Drive

To determine if repair is possible or replacement is necessary, perform the following procedure. See Figure "Flowchart for Repair or Replacement of Tachometer Drive" .‪

Figure 3. Flowchart for Repair or Replacement of Tachometer Drive

Section 9.5.2
Removal of Tachometer Drive Adaptor

Remove the tachometer drive adaptor as follows:‪

1. Disconnect the tachometer drive cable from the tachometer drive adaptor by unscrewing the bezel nut and pulling the cable straight out of the unit.
2. Unscrew the nut that retains the tachometer drive adaptor to the tachometer drive in the camshaft drive gear access cover.
3. Remove the tachometer drive adaptor.
4. Loosen and remove the five bolts that secure the camshaft drive gear access cover to the gear case cover.
5. Tap the cover with a rubber mallet or plastic hammer to break the gasket loose.
6. Remove the camshaft drive gear access cover/tachometer drive unit from the gear case.
7. Remove the tachometer drive shaft from the access cover.

Section 9.5.3
Cleaning of Tachometer Drive Adaptor

Clean the tachometer drive prior to inspection.‪

Clean all of the gasket material from the mating surfaces of the camshaft drive gear access cover and the gear case.‪

Section 9.5.3.1
Inspection of Tachometer Drive

Inspect the tachometer drive as follows:‪

1. Visually inspect the drive shaft for galling, scoring, or wear.
   1. If the drive shaft is damaged or excessively worn, replace with new part. Refer to "9.5.4 Installation of Tachometer Drive" .
   2. If the drive shaft is not damaged, reuse part. Refer to "9.5.4 Installation of Tachometer Drive" .
2. Inspect the tachometer drive shaft bushing for wear or damage.
   1. If bushing is excessively worn or damaged, replace tachometer drive gear access cover assembly as a unit. Refer to "9.5.4 Installation of Tachometer Drive" .
   2. If bushing is not worn or damaged, reuse part. Refer to "9.5.4 Installation of Tachometer Drive" .

Section 9.5.4
Installation of Tachometer Drive

Install tachometer drive as follows:‪

1. Lubricate the drive shaft with clean engine lubricating oil.
2. Install the drive shaft into the bushing in the access cover.
3. Using a new gasket, install the camshaft drive gear access cover tachometer drive unit to the engine by indexing the tachometer drive blade with the slotted camshaft drive gear retaining bolt. See Figure "Tachometer Drive Unit Installation" .
   

   Figure 4. Tachometer Drive Unit Installation

4. Install the camshaft drive gear access cover retaining bolts, and torque the bolts to 30-38 N·m (22-28 lb·ft) using the pattern as shown in the illustration. See Figure "Camshaft Drive Gear Access Cover Bolt Tightening Sequence" .
   

   Figure 5. Camshaft Drive Gear Access Cover Bolt Tightening Sequence

5. Index the tachometer drive adaptor shaft with the drive shaft.
6. Install the tachometer drive adaptor to the drive. Torque the nut to 12-15 N·m (9-11 lb·ft).
7. Index the tachometer drive cable to the adaptor, and install the cable. Finger-tighten the bezel nut.

   NOTICE:
   Do not use a power grease gun when lubricating the tachometer drive. Over-lubrication can damage the drive. One shot of grease with a hand operated grease gun is sufficient.‪

8. Lubricate the tachometer drive unit at the grease fitting using chassis lube.
9. Refer to "12.7 Engine Run-in Instructions" for verification of proper tachometer drive installation.