On manual transmission vehicles, a throw-out bearing is used. It’s a part of the clutch disengagement or release mechanism that occurs when the driver depresses the clutch pedal. As a result, it’s also known as a release bearing. The throw-out bearing is about the size of a small doughnut and is hidden from view from the outside. It, along with the clutch disc and pressure plate, two other clutch system components are housed inside the transmission bell housing.
When and how does the throw-out bearing come into play?
A fork pushes on the outside shell of the throw-out bearing and slides the bearing forward on the transmission input shaft when the driver depresses the clutch pedal. The face of the bearing then presses against the pressure plate’s “fingers.” This relaxes the springs that would otherwise clamp the clutch disc between the pressure plate and the engine’s flywheel, allowing the clutch and the engine-transmission connection to be released. This release allows the engine to continue to turn even when the wheels are stopped (for example, at a stoplight), as well as allowing the driver to shift gears.
You might not realize how difficult the throw-out bearing’s life is. Because the pressure plate springs are stiff, pushing on the pressure plate fingers takes a lot of effort. Because the outside of the throw-out bearing remains stationary while the face rotates with the pressure plate and its fingers whenever the clutch pedal is depressed, the term “bearing” is used.
When Does It Go Wrong?
Although the throw-out bearing should last as long as the clutch disc and should be replaced when the clutch is, some driving habits can cause it to wear out quicker. Because the throw-out bearing is activated whenever the clutch pedal is depressed, holding the pedal down for long periods of time, such as when waiting at a stoplight, can prematurely wear it out.
How’s that work? Well when the clutch pedal is depressed, a worn throw-out bearing makes a whirring or growling noise. It’s best to depress the clutch pedal, put the transmission in neutral, and release the clutch in those situations or any time the clutch would need to be held down for more than a few seconds.
