Experiencing a slight shake in the vehicle when pressing the brakes hard while in 'Drive' (D) mode is a normal phenomenon. This is because, in 'Drive' mode, the vehicle remains in a power-connected state. The engine's power is transmitted to the transmission, which then transfers it to the wheels via the drive shaft. Under these conditions, the vehicle should be moving forward. However, when you apply the brakes, it's akin to the transmission continually resisting that forward motion, leading to the shaking of the vehicle. Cars with good noise control and vibration isolation might still exhibit some shaking, but this will dissipate before reaching the car's interior.
However, if the shaking feels excessive, it might be due to damage to the engine mount pads. These pads, typically made of rubber, cushion the engine's vibrations. Without them, the engine's operational vibrations would directly transfer to the vehicle, affecting the ride's comfort. Additionally, over time, rubber components can age and harden. When engine mount pads degrade and harden, they might cause the engine's vibrations to directly affect the car's body.
Furthermore, it's advisable for drivers not to keep their foot on the brake for extended periods while in 'Drive' mode, as this can potentially damage the transmission. When waiting at a red light, aside from not pressing the brakes for too long in 'Drive' mode, it's also not recommended to shift to 'Park' (P) mode, as potential rear-end collisions could cause significant damage to the transmission.
