8 Causes for Abnormal Noise of the Car Gearbox

1. Bearing wear and damage. The worn bearing will increase clearance and let down the matching accuracy; A broken bearing will produce abnormal sound along with the normal operation of the bearing, or even damage gearbox components and cause the failure to expand.

2. Gearbox differential housing bolts loose. The vibration in the course can lead bolts loose, they should be regularly checked.

3. Shift lever and stainless steel shift fork groove in the manual transmission are loose.

4. Automatic transmission fluid has not been changed for a long time. The transmission oil will get thicker and less fluid, so there is no protective layer of friction between the parts and thus aggravate the wear of mechanical parts finally causing abnormal sound. 

5. Replace the low-quality automatic transmission oil. The oxidation of gearbox oil that easily made because of the poor temperature resistance, is prone to cause sludge and greaves clogging filter and oilway, enlarging frictions within the automatic transmission components and causing abnormal sound of the vehicle.

6. In the replacement of gearbox components, if the new one to be choosed is in low precision, that will lead to the excessive clearance, or too tight gear clearance presented in assembly.

7. Metal flaking, gear teeth broken, assembly dislocation.

8. Gearbox is not promptly repaired after water, which may cause abnormal sounds after a long time.