What Causes the Thud Sound When Starting an Automatic Transmission Car?

1 Answers
ORemington
07/30/25 1:36am
Automatic transmission cars make a thud sound when starting because the brake pads stick to the brake discs after releasing the handbrake, and the sound is produced when the brake pads snap open under force during startup, which is a normal phenomenon. Below is relevant information about automatic transmissions: 1. Introduction to Automatic Transmissions: As the name suggests, an automatic transmission does not require the driver to manually shift gears; the vehicle automatically selects the appropriate gear based on driving speed and traffic conditions. Typically, automatic transmission cars have six gear positions, arranged from top to bottom as: P, R, N, D, S, L. 2. Working Principle: An automatic transmission uses planetary gear mechanisms to shift gears, automatically adjusting based on the degree of throttle pedal pressure and changes in vehicle speed. The driver only needs to control the speed using the accelerator pedal.
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