What Causes the Loud Bang When Shifting to D Gear?
3 Answers
The reasons for a loud bang when shifting to D gear include excessively high engine RPM, insufficiently pressed brake, or premature brake release. Details are as follows: Excessively High Engine RPM: When the engine is cold and just started, the RPM may be too high. At this time, the torque converter transmits more power, resulting in greater impact force and more noticeable shaking when shifting gears. Insufficiently Pressed Brake: When shifting gears, the engine's power is directly transmitted to the wheels. If the brake is not pressed firmly, the wheels may move slightly during gear shifting, causing the vehicle to suddenly jerk forward with a strong sense of shaking. Premature Brake Release: When the brake is released, the vehicle may suddenly lurch forward violently. This happens because the brake is released too early, causing an abrupt combination of power. Since the gear lever of an automatic transmission does not directly control the gear position but serves as a signal device, different signals are sent to the transmission control system after engaging different gears, and the transmission control system then completes the gear shift.
When starting the car and shifting into D gear, I suddenly heard a loud bang. I think this issue is quite common, usually related to the transmission or drivetrain. For example, excessive impact when shifting gears could be due to insufficient or deteriorated transmission fluid, causing abnormal friction between internal gears and resulting in strange noises. Another possibility is a loose or damaged driveshaft, where the increased load when the car starts generates vibrations and noise. Another reason could be aging or failed engine mounts, causing the engine to shift when changing gears. I've experienced a similar situation myself while driving, and later found out it was because the transmission fluid was dirty and hadn't been changed in time. So I recommend starting with checking the fluids: open the hood and check if the transmission fluid level is within the normal range and if the color is clear. If everything seems fine, inspect the undercarriage for any obvious looseness. Timely repair is crucial because this noise could indicate more serious drivetrain issues, affecting driving safety. It's best to have it checked at a professional shop with diagnostic tools. Additionally, developing a habit of regular maintenance can help avoid neglecting minor issues over time.
My old car often makes a loud 'bang' sound when shifting into D gear, which is quite startling. I believe this is mainly due to internal transmission issues. Gear wear or clutch slippage can cause such impacts, as the D gear is the forward drive and experiences high instantaneous pressure during startup. It could also be due to a faulty shifting mechanism, such as loose linkage or poor electrical connections. I learned this back when I drove trucks in my younger days—loud noises usually indicate serious problems that could lead to the car breaking down midway, which is especially dangerous. So, I advise everyone not to ignore such sounds and to pull over immediately, turn off the engine, and check if any fuses are blown or if there are unusual marks under the chassis. If you're not sure how to handle it, call for roadside assistance. Safety comes first—don’t risk driving to save time. Always pay attention to your car’s condition and change the transmission fluid regularly to avoid many potential issues.
