What Causes Gear Shift Impact in Automatic Transmissions?

[LaJocelyn]

There are several possible reasons for gear shift impact in automatic transmissions: 1. Burnt clutch plates in the transmission (with a burnt smell). 2. Fault codes appearing in the transmission system (repairs can be made based on the fault code prompts). 3. Sticking of internal valve bodies in the oil control plate. 4. Presence of impurities in the oil passages, causing delays in the automatic transmission control valve and resulting in gear shift impact. 5. Insufficient transmission fluid level. Below are some maintenance tips for automatic transmissions: 1. Regularly check the automatic transmission fluid level to ensure it is normal. 2. Be aware of the replacement cycle for automatic transmission fluid. 3. Replace the transmission fluid correctly.

[KateLynn]

My car also had gear shift shock issues before, which were particularly noticeable when starting from a stop at traffic lights. Later, during a check at the shop, it was found that the main reason was the transmission fluid hadn't been changed for 100,000 kilometers and was terrifyingly full of contaminants. The mechanic said unstable oil pressure could cause gear shift jerks, and more seriously, carbon deposits had jammed several control valves inside the valve body. They also found poor contact in the transmission control module's connector, causing the computer to receive inaccurate speed signals. Now, changing the fluid every 60,000 kilometers is a must. Don’t make the same mistake as me by waiting until the fluid turns into sludge, which ended up costing me thousands to replace the entire valve body assembly.

[ElliotFitz]

As a veteran driver with twenty years of experience, the most common causes of gear shift shock fall into three scenarios. First, excessive wear on the clutch disc can cause sudden engagement and jerking when it slips. Second, aging or broken engine mounts lead to engine movement that pulls on the transmission lines. Third, issues with the transmission control unit (TCU) programming, particularly during cold starts where the logic may not be optimal. These faults must be addressed promptly. I once had a client who ignored minor jerking for too long, which eventually burned out the transmission friction plates, resulting in a major overhaul costing over ten thousand.

[WilliamLee]

From a design perspective, gear shift shock in automatic transmissions is essentially a manifestation of discontinuous power transfer. When the computer issues a shift command, the hydraulic pressure needs to precisely control the clutch engagement torque. If the oil temperature is too high, causing the hydraulic fluid to thin, or if the spring valve core in the valve body is worn, the hydraulic pressure curve becomes erratic. Common failure points also include the torque converter's lock-up clutch, which is prone to overheating due to frequent stop-and-go driving in urban areas. It is recommended to monitor the transmission oil temperature gauge and switch to manual mode during prolonged traffic congestion to prevent overheating.