Clutches, Rear Axles, and Steering Clutches General Information Clutch Operation Starting the Vehicle in the Correct Gear To drive forward, always start in first gear. After the clutch is fully engaged, the engine should be acceler- ated to the correct rpm for the upshift into the next higher gear. The major reason clutches wear out too soon is exces- sive heat. Clutches are designed to absorb and dissi- pate more heat than encountered in typical operation. The temperatures developed in typical operation will not break down the clutch friction surfaces.
However, if a clutch is slipped excessively, or required to do the job of a fluid coupling, high temperatures develop quickly and destroy the clutch. Temperatures generated between the flywheel, driven discs, and pressure plates can be high enough to cause the metal to flow and the friction facing material to char and burn. Gear Shifting Techniques Many drivers upshift into the next gear, or even skip- shift into a higher gear, before the vehicle has reached the correct speed. This type of shifting is almost as bad as starting off in a gear that is too high, since the en- gine rpm and vehicle speeds are too far apart, requiring the clutch to absorb the speed difference by generating heat.
For transmission operating instructions, see Chapter 5 . Slipping and excessive heat are practically nonexistent when a clutch is fully engaged. But during the moment of engagement, when the clutch is picking up the load, it generates considerable heat. An incorrectly adjusted or slipping clutch will rapidly generate sufficient heat to destroy itself. Vehicle Overload, or Overloading the Clutch Clutches are designed for specific vehicle applications and loads. These limitations should not be exceeded. The most important items that a driver should be aware of to ensure long service life of the clutch include:
start- ing in the right gear, recognizing clutch malfunctions, and knowing when to adjust a clutch. CAUTION Overloading will not only result in damage to the clutch, but also to the entire powertrain. 6.1