Why Does the Car Shake After Shifting into Gear in an Automatic Transmission?
4 Answers
Automatic transmission car shaking after shifting into gear may be caused by: the transmission gear oil being too viscous and dense; the drivetrain receiving engine power more noticeably. Starting an automatic transmission car: When starting an automatic transmission engine, the gear selector must be placed in the P or N position, with the handbrake engaged or the brake pedal depressed. To start the car, first press the brake pedal, shift into gear, release the handbrake, then smoothly lift the brake pedal. Once the car starts moving slowly, gradually press the accelerator pedal. Shifting on slopes with an automatic transmission: You can control the car's speed uphill and downhill in D gear using the accelerator and brake pedals. For longer or steeper slopes, shift the gear selector from D to 2 or L position.
Last time I encountered the whole car shaking like a phone on vibrate mode when shifting to D gear, and it turned out the engine mount was shot. This thing is essentially the engine's anti-vibration cushion - when the rubber deteriorates and cracks, it loses its damping effect. Cars over three years old are particularly prone to this issue, and you'll often notice slight RPM fluctuations when shifting gears while stationary. Besides engine mounts, worn CV joints can also cause severe shaking during initial acceleration, sometimes accompanied by clicking noises when turning. If the steering wheel vibrates too, you should also check tire balance and suspension bushings. Never delay fixing these issues - the longer you let it shake, the more damage it does to transmission mounts.
I experienced this before with my old Camry—when stopped at a red light in D gear, the shaking was so bad it sent ripples through the water in my cup. This is most commonly caused by unstable engine combustion, especially in direct-injection vehicles prone to carbon buildup clogging the fuel injectors, leading to a misfiring cylinder. My go-to fix is revving the engine a few times at high RPM; if the symptoms ease, it’s likely carbon deposits. Another common issue is incorrect air-fuel ratio—a dirty mass airflow sensor or a contaminated oxygen sensor can trick the ECU into miscalculating fuel injection. For those who often drive slowly in the city, it’s important to prevent water buildup in the fuel tank, as a clogged fuel filter can also cause shaking.
Transmission fluid is crucial. Once, my car experienced gear-shifting impacts and shaking, and when I changed the fluid, I found the oil pan full of metal shavings. When automatic transmission hydraulic fluid deteriorates, power transfer efficiency plummets, and torque converter lock-up clutch slippage can cause jerking. It's recommended to change the fluid every 60,000 kilometers, and replacing the filter at the same time yields better results. Hybrid vehicles require extra attention to motor bearings, as lack of lubrication can cause high-frequency vibrations. Loose wire harness clips in the engine bay can also lead to resonance noises.
