Is It Harmful for an Automatic Transmission to Roll Forward in Reverse Gear?
2 Answers
Rolling forward in reverse gear (R) can cause significant harm to an automatic transmission. When an automatic transmission vehicle rolls forward without being shifted into R gear, it generally does not affect the transmission because the vehicle is in neutral (N) or drive (D) position, which are normal gear settings. However, if the vehicle is shifted into R gear while still moving forward, causing it to roll, this action can increase wear on the transmission and potentially lead to gear grinding, which is a highly dangerous practice. Below is relevant information: Precautions for Automatic Transmission Roll: If an automatic transmission vehicle rolls backward during hill starts, it is likely due to insufficient idle speed when only in D gear without applying throttle. This can cause the engine to stall, as it cannot provide enough power to start the vehicle on a slope. Once rolling occurs, it becomes even more difficult to avoid stalling, as the engine must not only provide mechanical energy for starting but also counteract the kinetic energy from rolling backward. In such cases, the driver must first press the brake and clutch to stop the vehicle completely before restarting. Automatic Transmission Power Delay: After releasing the pedal, automatic transmission vehicles experience a power delay of about one second, which is more pronounced in dual-clutch transmission models. When starting an automatic vehicle, releasing the brake triggers this power delay, which can be long enough for the vehicle to roll backward.
Having driven for decades, I've encountered quite a few incidents where the car rolls forward when shifted into reverse in automatic transmissions, which can be truly hazardous. Beginners often experience this when their foot isn't firmly on the brake on slopes, leading to rolling. At best, it wears out the transmission gears, costing a few thousand to repair; at worst, it can cause accidents by hitting obstacles. For instance, a neighbor once rolled into a wall, damaging the internal oil pump of the transmission, which cost over ten thousand to replace. What's even more concerning is rolling in parking lots or streets, where hitting a person or another vehicle could lead to serious trouble. I believe the key is to develop the habit: always press the brake firmly before shifting gears, and release it slowly. Safety is no trivial matter—small mistakes with fragile machinery can lead to major disasters. Practicing proper operations regularly saves hassle, money, and even lives.
