When it comes to cars, driving a manual, or stick shift, is just that--manual. A manual transmission requires that you push in a clutch to release the gears of the engine so you can shift. Changing gears allows the engine to run at a different rate of speed. Because a clutch controls the action of the engine, its smooth operation is integral to a car's function. A clutch can stop functioning or go out for any number of reasons. When a clutch is going out, there are a couple of signs that make it obvious.
Slipping is due to a natural process of wear and tear on a clutch. Gradually, the clutch loses the ability to hold the parts it's supposed to hold tight. The driven disc is not held tight against the fly wheel, and the parts fail to rotate at the same rate of speed. Signs of a slipping clutch occur first in the car's engine speed and RPM reading; the engine speed and RPM increase when the car is sitting still, or barely accelerating.
Clutch grabbing occurs when there's a problem with the components of a clutch, which keeps the clutch from operating smoothly. Grabbing or chattering is when the clutch causes the car to vibrate or jerk during acceleration. The car will feel like the clutch is being abruptly pressed and let out, even if the clutch is depressed the entire time.
A dragging clutch happens when depressing the clutch petal fails to fully free the fly wheel in the engine. This means that the parts of the engine that would normally stop turning when you clutch and shift are instead still turning as you attempt to shift. This results in grinding and clunking during shifting, as though the clutch petal is not depressed at all.
Any time a clutch is malfunctioning, it will cause abnormal noise. The noises might be obvious when the clutch is engaged or disengaged, and can range from scraping to clunking and chinking. These noises are usually factors of a clutch that has several internal pieces that are malfunctioning.
If the clutch petal is vibrating it means that one of the rotating pieces of the clutch is wearing out. This can also be caused by a misalignment between the clutch and the other parts of the engine.