What does “rev matching” help to achieve during a downshift?

Rev matching is a technique used during downshifts in manual transmissions to synchronize the engine speed with the speed of the wheels. This process ensures that when the driver downshifts to a lower gear, the engine revs high enough to match the rotational speed of the transmission input shaft. By doing so, it prevents the vehicle from experiencing jolts or sudden changes in speed, which could otherwise lead to loss of control or abrupt handling characteristics.

When a driver downshifts without rev matching, the engine speed may be too low relative to the wheel speed, resulting in a sudden deceleration of the wheels, which can cause unwanted handling effects and tire wear. Through rev matching, the smoother transition between gears allows for a more controlled and stable driving experience, which is particularly important during spirited driving or when navigating curves.

This technique is commonly used in performance driving and is beneficial for maintaining vehicle stability and comfort while also enhancing the overall driving experience. It emphasizes the importance of coordinating the engine's output with that of the drivetrain during shifts for optimal performance.