Why Does the Transmission Gear Grind?

[LandonLee]

Transmission gear grinding usually occurs when the gear is not properly engaged. If the clutch is not fully disengaged during gear shifting, not only will there be gear noise, but it can also easily lead to gear grinding. Additionally, if the transmission lubricant contains large impurities, such as iron filings from long-term wear, and these get caught between the transmission gears during rotation, it can also easily cause gear grinding. Transmission maintenance: 1. Regular inspection: It is essential to regularly check the fluid level in the transmission to ensure it remains within the specified range and top it up as needed based on actual working conditions. When topping up, ensure that the new fluid is of the same type. When changing the fluid, do it while the transmission is operating to promptly drain the old fluid and clean the system. Regularly inspect the working condition of the transmission gears to ensure optimal meshing between gears, and clean them promptly to maintain proper alignment between gears and shafts. 2. Adjust driving habits: Continuously improve driving habits during daily use. When shifting gears, use the prescribed methods to prevent gear damage, lever fork damage, and other issues related to the shift lever.

[HannahLee]

The most common cause of gear grinding in manual transmission cars is primarily due to improper operation. For example, when shifting gears, if the clutch isn't fully depressed while power is still being transmitted, the gears will clash and make noise. Additionally, the timing of gear shifts is crucial—shifting at too high or too low RPMs can easily cause gear grinding. I've seen many people driving manual cars hastily pushing the gear lever without fully engaging the clutch, which can significantly damage the synchronizers over time. Moreover, degraded or insufficient gear oil increases friction, making the synchronizers work less smoothly. If you notice an increase in gear grinding, it's best to check the clutch travel or switch to a high-quality gear oil.

[AlanaMarie]

Structurally, gear grinding in the transmission mainly occurs when the synchronizer fails to match the rotational speeds. Before gear shifting, the synchronizer needs to use friction to equalize the rotational speeds. If the synchronizer ring is severely worn or the gear oil is too viscous, resulting in insufficient friction and excessive speed difference, the gears will collide directly. Having disassembled many transmissions, I've found that reverse gear is most prone to grinding because reverse gears usually lack synchronizers. Additionally, if shifting is done too roughly, gear grinding can occur even if the synchronizer is still functioning. It's recommended to shift gears gently while driving, allowing some buffer time for the synchronizer. Regularly checking the condition of the gear oil is also crucial; if it darkens in color or contains metal particles, it should be replaced promptly.

[LaKarter]

Once when I was driving my old car, I experienced severe gear grinding with loud clunking noises throughout the cabin. The mechanic later explained that the cause was a leaking clutch slave cylinder - when fully depressed, the release bearing didn't have enough pressure to completely disengage the power. If gear grinding occurs frequently during shifting, it might be due to air in the clutch hydraulic system or insufficient fluid. Additionally, loose transmission mounts can also lead to gear grinding, as excessive engine vibration during driving affects gear meshing. The most troublesome issue is damaged second gear synchronizer rings, which make shifting particularly difficult accompanied by screeching noises. If you notice these symptoms, don't hesitate to get it inspected immediately, otherwise the entire transmission gears could be ruined.