What causes the vehicle to shake slightly after shifting into P gear when parking?
2 Answers
Detailed explanation of the slight shaking after shifting into P gear when parking: 1. According to the structural design of automatic transmissions, the P gear is designated as the parking gear. The principle involves a parking pawl that engages with the ring gear. As long as the gear is engaged, it remains in constant motion. The locking mechanism of the P gear is achieved through the interaction between the output shaft gear inside the transmission and the locking pin, which is why the vehicle cannot move forward or backward once P gear is engaged. The steeper the slope, the greater the force required. For this situation, it is recommended to first bring the vehicle to a complete stop, apply the handbrake, and then shift into P gear for better results. 2. Issue with the lock-up clutch. The transmission contains a lock-up clutch. When shifting into P gear, if the clutch lock pin is not properly engaged, the vehicle may shake slightly as it settles into the lock-up clutch.
This phenomenon is actually quite common, mainly due to the normal mechanical impact generated when the P-lock mechanism engages. When you shift from D to P, the locking pawl inside the transmission clicks into the groove of the drive gear, creating a brief reactive force throughout the drivetrain. Especially when parking on a slope, if you don't apply the parking brake first, the vehicle's weight will cause the car to slide back slightly before being abruptly stopped by the P-gear, naturally creating that rocking sensation. I recommend trying this sequence next time you park: After coming to a complete stop with the foot brake, first shift to neutral, then firmly engage the parking brake to ensure the vehicle doesn't move at all. Next, release the foot brake to confirm the car isn't sliding before finally pressing the brake to shift into P and turn off the engine. Once you develop this habit, you'll hardly notice any rocking.
