What Causes the Abnormal Noise in a Manual Transmission?

[HavenDella]

Transmission gear noise is usually caused by low or deteriorated transmission fluid level, excessive or insufficient gear meshing clearance, or poor gear engagement. When the meshing clearance is too large, the driving gear impacts the driven gear during rotation, producing a knocking sound, which typically worsens as the transmission temperature rises. Bearing wear and damage: When bearings wear out, the clearance increases and the fitting accuracy decreases; when bearings are damaged, abnormal noise occurs due to their inability to operate normally, which may even lead to damage of transmission components and exacerbate the fault. Abnormal gear meshing clearance: Excessive clearance due to worn transmission components or the use of low-precision replacement parts; excessively tight gear clearance during assembly.