- Off-Highway Truck/Tractor:
- 784B (S/N: 5RK1-UP)
- 784C (S/N: 2PZ1-UP)
- 785 (S/N: 8GB1-UP)
- 785B (S/N: 6HK1-UP)
- 785C (S/N: 1HW1-UP; APX1-UP)
- 785C HAA (S/N: 5AZ1-UP)
- 789 (S/N: 9ZC1-UP)
- 789B (S/N: 7EK1-UP)
- 789C (S/N: 2BW1-UP)
- 793B (S/N: 1HL1-UP)
- 793C (S/N: 4AR1-UP; 4GZ1-UP; ATY1-UP)
Reference: Service Magazine, SEPD0479, 5 July 1999, "New Clutch Discs With Improved Core Material Now Available for Large Off-Highway Trucks"
Description of Change: New discs with improved friction material are used in the transmission arrangements. In heavy-duty applications, the new friction material will improve the service life.
Adaptable To: Do not mix the new discs with the former discs in the same clutch. The new discs are visually identical to the former discs. The new discs must be identified by the part number. See Table 1 for the part numbers. See Table 2 for the effective serial numbers.
| Part Numbers of the Friction Discs | ||
| Model | New Part Number | Former Part Number |
| 784B, 784C, 785, 785B, 785C, 789, 789B, 789C, 793B, 793C | 173-3270 | 158-3750 |
| 784B, 784C, 785, 785B, 785C, 789, 789B, 789C, 793B, | 173-3271 | 158-3752 |
| 793C | 173-3272 | 158-3753 |
| Effectivity of Friction Discs | ||
| Model | Transmission Arrangement | Effective Serial Number |
| 784C, 785C | 3T-0034 | S/N:2BE03260 |
| 789C | 6Y-5645 | S/N:6LE01266 |
| 793C | 9U-9822 | S/N:4GX01350 |
 | |
| Illustration 1 | g00833970 |
(A) Circumferential grinding marks (B) Grinding marks that are not circumferential | |
The new clutch discs are intended for use with mating parts that have circumferential grinding marks. The mating parts can be reused without regrinding the surfaces. The mating surfaces must not be smeared with friction material. The surfaces must also be free of pits. If new mating parts are used, these parts need surfaces with a circumferential grind.