What Causes the Transmission Jerking in Corolla 1.2T?
2 Answers
Corolla 1.2T transmission jerking mainly occurs during gear shifting and deceleration. Gear Shifting Jerking: Upshift jerking is mostly caused by the transmission's response speed being insufficiently fast, where the upshift speed cannot keep up with the throttle input speed. Therefore, when the transmission shifts gears, a jerking sensation occurs. Downshift jerking is primarily due to the intervention of the energy recovery system. Once the driver releases the throttle pedal or presses the brake pedal, the generator immediately starts working, which places some load on the engine, affecting the engine speed and causing a mismatch between the engine speed and the clutch plate speed, resulting in a jerking sensation. Low-Speed Jerking: During low-speed driving, the frequent switching between first and second gears causes the clutch to continuously engage and disengage, preventing smooth power transmission in a short time. This leads to the common low-speed jerking sensation. Jerking during startup and low-speed driving occurs when the turbocharger intervenes at low RPM, affecting the engine speed.
I drove a Corolla 1.2T for a while and also experienced transmission jerking issues. It felt like the car would clunk and get stuck when starting or shifting at low speeds. This is mostly a transmission fluid problem, such as insufficient fluid level or degraded fluid quality, which affects lubrication and hydraulic power transfer. The Corolla uses a CVT transmission, which is prone to minor jerking during cold starts or low-speed driving by design. However, if it happens too frequently, you should check the fluid lines or solenoid valves. I recommend regular maintenance, changing the factory fluid every two years, and avoiding sudden acceleration or deceleration while driving to maintain a steady speed. If the problem persists, take it to a dealership for a software update or hardware inspection. This can prevent minor issues from becoming major ones and ensure smooth and safe driving.
