Why does the speed increase when pressing the clutch downhill?
2 Answers
Because pressing the clutch is equivalent to cutting off the engine power, which is like coasting in neutral. Without engine braking, the speed actually increases. Hazards of pressing the clutch downhill: The hazard of pressing the clutch downhill is that it can easily cause excessive wear to the clutch system. When the clutch pedal is pressed, the release bearing pushes the pressure plate spring to separate the pressure plate, and the contact surface of the release bearing with the pressure plate will rotate at high speed with the pressure plate. The release bearing has a certain lifespan, and continuously pressing the clutch will keep the release bearing in high-speed rotation, significantly reducing its lifespan. Downhill driving techniques: Before descending, reduce the speed to enter the downhill slope at a slow pace; shift to an appropriate gear before descending, generally choosing second or third gear. It is strictly forbidden to shift gears after entering the downhill section; coasting in neutral is prohibited in downhill sections, and an appropriate gear must be engaged to use the engine's braking effect to reduce the coasting speed; test the braking performance before descending, and if there are any issues, resolve them before descending. Use brakes cautiously in downhill sections.
I totally relate to this issue, having personally experienced it on a mountain road before. The phenomenon of the car speeding up when the clutch is pressed downhill is actually a matter of physics: pressing the clutch effectively disconnects the engine from the wheels, making the car behave like a runaway horse with gravity fully acting on the vehicle. Normally, the engine provides a restraining effect, especially in lower gears where higher RPMs offer stronger resistance, but this braking effect disappears once the clutch is engaged. So, the steeper the slope and the lower the gear, the more pronounced the acceleration feels when suddenly pressing the clutch. However, experienced drivers generally advise against pressing the clutch downhill—not only does it harm the transmission, but it also removes a crucial safety measure in critical moments.
