What Causes Abnormal Noises in a Manual Transmission?

[ArcherLynn]

Manual transmission abnormal noise causes: Typically caused by low or deteriorated transmission fluid level, excessive or insufficient gear meshing clearance, or poor gear meshing. When the meshing clearance is too large, the driving gear impacts the driven gear during rotation, producing a knocking sound. When the meshing clearance is too small, the abnormal noise is usually continuous—sometimes uniform, sometimes uneven—and worsens with increasing vehicle speed, potentially overheating the transmission lubricant. A manual transmission is a gear-shifting device that alters the engine's speed and torque delivered to the drive wheels, enabling the vehicle to achieve varying traction and speed during scenarios like stationary starts, hill climbing, turning, and acceleration, while keeping the engine operating within a more favorable range.