Output Shaft
The shaft in a transmission that transfers rotational power to the driveshaft or axles.
The output shaft is the rotating metal shaft extending from the rear of the transmission or transfer case. It is the final link in the transmission's gear train, transferring the modified engine torque and speed from the internal gears to the driveshaft or axles to drive the vehicle's wheels.
The output shaft is splined at its outer end to accept a driveshaft slip yoke or companion flange. A rear transmission seal (output shaft seal) rides on the smooth surface of the yoke to prevent fluid leaks while allowing the shaft to rotate. The speed of the output shaft is monitored by the vehicle speed sensor (VSS) to feed speed data to the computer.
A bent or worn output shaft, often caused by driveshaft imbalance or universal joint failure, will create high-frequency vibrations that increase with vehicle speed. It can also cause rapid wear of the output shaft seal and tailhousing bushing, leading to transmission fluid leaks and mechanical failure.