ASE Automobile and Light Truck Certification Manual Transmission (A3) Practice Test

After cleaning and drying a transmission mainshaft rear bearing, it is important to lubricate the bearing raceways lightly with oil. This process is crucial because the lubrication provides the necessary film between the moving components, thereby reducing friction and wear during operation. Proper lubrication also aids in heat dissipation and helps to prevent premature failure of the bearing.

Using oil for lubrication ensures that the bearing can handle the high speeds and loads typically encountered in a transmission system. Unlike grease, which can trap debris and may not allow for adequate fluid movement, oil flows easily within the bearing, ensuring consistent coverage and minimizing the risk of damage. Leaving the bearing dry is not advisable, as unlubricated components can lead to metal-to-metal contact, resulting in significant damage. Discarding the bearing would be unnecessary if it is still in good condition after cleaning and can be effectively lubricated.