What Causes the Clunking Sound When Reversing in an Automatic Transmission Vehicle?
3 Answers
Automatic transmission vehicles producing a clunking sound when reversing is typically caused by shift shock. Below are potential causes and corresponding solutions: 1. Faulty clutch plates inside the transmission. Solution: If the transmission fluid emits a burnt smell, it indicates the clutch plates have burned out. Transmission repair is required. 2. Transmission system malfunction: Solution: If the transmission system shows error codes, repairs should be performed based on these codes (always visit a professional auto repair shop). 3. Faulty hydraulic control module: Solution: If internal valves in the hydraulic control module are damaged, visit a repair shop for servicing.
Once when I was reversing, I heard a 'thud' and thought I had hit something, but when I got out to check, there was nothing there. Later, I realized that the underbody guard plate had come loose and was scraping against the exhaust pipe during reversing. Experienced drivers like me would first check if the tires had run over a stone or got stuck with a foreign object, and then inspect whether the underbody guard plate was deformed. If you often drive on rough roads, the wear on the small link bushings of the suspension system can also cause strange noises when reversing and turning. It's best to record the specific conditions under which the noise occurs, such as whether it happens every time you reverse or only occasionally, so that the mechanic can more easily identify the issue when you take it in for repairs. If the noise comes from the transmission, you should be even more alert, as it might indicate a problem with the reverse gear, which is usually accompanied by a continuous clicking sound.
I've been repairing cars for over a decade and have encountered many customers complaining about reverse gear noise issues. The most common cause is the braking system, such as when the handbrake isn't fully released, causing the brake pads to rub against the discs, producing a sound like metal scraping. Another frequent issue is wear in the driveshaft carrier bearing, which can create a 'clunking' noise when reversing due to the change in load direction. Once, a customer reported chassis noise, only for us to discover it was simply a loose exhaust hanger bolt. My advice is to first try shifting gears while stationary to listen for noises—if the noise occurs when shifting into reverse, it's likely a transmission problem. If the noise only appears when actually moving in reverse, focus on checking suspension bushings, CV joints, or wheel bearings. Some minor issues can be handled yourself, like removing small stones stuck in the wheel hub.
