What Causes the Clicking Sound When Shifting an Automatic Transmission?
4 Answers
Automatic transmission shifting produces a clicking sound due to: 1. Generator gear issues: The symptom is a clicking sound when shifting into D or R gear while pressing the brake, but no sound in N gear, and no abnormal noise while driving. The solution is to replace the generator. 2. Large valve clearance and poor lubrication when the engine is cold: The symptom is a clicking sound during gear shifting between cold and warm engine states, lasting about 3 minutes, which is normal. An automatic transmission eliminates the need for manual gear shifting by the driver, as the vehicle automatically selects the appropriate gear based on speed and traffic conditions. Typically, automatic transmission cars have six gear positions, from top to bottom: P, R, N, D, S, L.
A couple of days ago, I also heard a clicking sound when shifting gears while driving. My friend said it's the normal sound of mechanical engagement. When an automatic transmission shifts from P to D, the gearbox locks the gears, and that's where the sound of the gears clicking into place comes from. It's best to fully depress the brake when parking before shifting gears, and on slopes, engage the handbrake first before shifting to P. But if the sound occurs when the car is warm but not when it's cold, it might be due to dirty transmission oil causing insufficient lubrication. Once, I forgot to service it and noticed the sound getting louder, but after changing the oil, it became much quieter. If there's also body vibration, it could be due to aging half-shafts or engine mounts. Don't delay on this; it's safest to have a reliable repair shop check it out.
After driving automatic transmission cars for over a decade, I've noticed two types of clicking sounds. The normal one is the sound of gear engagement in the shift mechanism, like a light click when a door lock latches. But if the sound is particularly loud and accompanied by vibration, it's cause for concern. It could be due to worn valve bodies inside the transmission causing unstable oil pressure and impact, or misaligned shift cables from loosening. Remember to check the transmission fluid color – if it's black and has a burnt smell, it's time for a change. Once I checked the dipstick myself and found the fluid level too low; adding some fluid improved things significantly. Persistent rough shifting like this can damage the transmission, and the repair costs could buy you new tires. Addressing it early is the right thing to do.
Don't panic if you hear gearshift noises. When I inspect cars for others, I always clarify first: Does it only happen during cold starts or also when the engine's warm? Is the sound coming from the shift lever position or the chassis? If it's from the chassis, it's likely due to worn driveshaft splines - the clicking sound will intensify or weaken with throttle input. If it only occurs when shifting to Reverse, the reverse gear might be worn. In one case I encountered, the owner had modified the exhaust system, and the resonance loosened the transmission mount bolts - tightening them solved the issue. For electronic shifters, it could be a software glitch; try rebooting the system. If you're still concerned, reading the trouble codes is far more reliable than random guesses.
