What Causes the Abnormal Noise in Passat?

[VonMaria]

If there is abnormal noise during gear shifting at low speeds and the sound is relatively minor, it could be due to internal components of the transmission wearing out and producing noise during operation. Worn Transmission Bearings: Transmission bearings often operate under high-speed, heavy-load conditions and endure significant alternating loads. As a result, the rolling balls or cylindrical rollers and raceways of the bearings may experience wear, spots, fatigue spalling, or burning, leading to increased axial and radial clearances, which can cause impact noise. Worn Meshing Gears: During gear meshing and transmission, sliding friction occurs from the tooth tip to the tooth root, making wear inevitable. Due to gear wear, the meshing clearance increases, causing impact noise during vehicle operation, such as when starting or shifting gears.