What Causes Transmission Whining Noise?

[LePatrick]

Excessive gear meshing clearance in the transmission. When the gear meshing clearance is too large, the driving gear impacts the driven gear during rotation, producing knocking sounds that typically worsen as transmission temperature rises. Conversely, when the meshing clearance is too small, the abnormal noise tends to be continuous - sometimes uniform, sometimes irregular - intensifying with vehicle speed and often causing transmission lubricant overheating. Additional note: Gear noise may also result from damaged gear tooth surfaces, producing irregular yet rhythmic sounds that amplify with throttle input. In severe cases, transmission vibration may be felt.