What Causes the Rattling Noise in the H6 Transmission?
3 Answers
Here are the reasons for the rattling noise in the H6 transmission: 1. Bearing wear: Loose bearings due to wear, deformation of the shaft or housing causing changes in the center distance between meshing gears and misalignment of axes. 2. Spline groove wear: Wear of the sliding keyway on the shaft and the internal spline groove of the sliding gear; loose fastening bolts in the control mechanism and wear or deformation of the shift fork, leading to gear displacement. 3. Improper operation: Incorrect driver operation, such as aggressive starts or poor coordination between hand and foot during gear shifting, can cause significant impact loads in the transmission, resulting in broken or shattered gear teeth and subsequent noise.
My old H6 manual transmission had a similar issue before. The mechanic found it was due to a loose clutch release bearing. This part is connected to the pedal, so every time you press the clutch, it rotates the bearing. If the bearing lacks lubrication or is worn, it will produce a continuous clicking sound, especially noticeable at idle. Additionally, wear on the transmission input shaft bearing can cause a rattling noise when you release the throttle. I recommend paying attention to the location of the sound—if it's coming from the front of the engine bay, it's likely one of these two bearing issues. Two years ago, I replaced mine with an imported bearing, which cost over 300 yuan, and also updated the pressure plate. Now, after 50,000 kilometers, the noise hasn't returned.
Has anyone driving the dual-clutch version encountered a similar situation? Last year, my car always made a metal clanking sound during low-speed gear shifts. The dealership inspection revealed excessive clearance in the shift fork. That aluminum fork controls gear engagement, and if it's excessively worn, it will produce a loud clunk during gear shifts. Another easily overlooked issue is the aging of the shift cable rubber boot. When the rubber cracks, the cable directly rubs against the bracket, causing a rattling sound whenever the car moves. Neither of these situations is complicated to fix—just replace the part and adjust the clearance. However, it's best to address them early, as prolonged neglect could damage the synchronizer ring gear.
