Why Does My Car Jerk When Changing Gears?by Juliana Torres
Driving a car with a manual transmission can be tricky. Drivers learning how to drive a stick shift could end up with an unpleasant ride if they poorly execute the transition between gears, causing the car to jerk forward or backward. However, understanding how your car works could help smooth your drive. The key is timing.
A manual car has three pedals: one on the far right to control the gas, a break in the middle and the clutch on the far left. The gear shifter, usually in the middle console, allows you to change gears. All of these pieces are involved in initially moving the car, speeding it up and slowing it down. To get the car moving forward, you must push down the clutch, shift into first gear and gradually let off the clutch, while alternately pushing down on the gas pedal. Shifting between gears requires a similar, but less touchy process. You release the gas pedal, push down on the clutch, shift the gear shifter, and then release the clutch. You can then give the engine more gas.
What the Clutch Does
To understand why your car is jerking between gears, you should understand what the clutch in your vehicle does. Basically, it provides the transition between a constantly spinning engine and your wheels, which may or may not be spinning. Engaging the clutch, which occurs when your foot is off the corresponding petal, allows the clutch plate to make contact with the spinning flywheel of the engine and transfer that torque through the transmission to the wheels. Disengaging the clutch when your foot pushes on the petal releases that pressure from the clutch plate, at which point you can shift without the gears grinding together.
In the few moments while you disengage the clutch, shift gears, engage the clutch and reapply the gas, your engine revolutions per per minute have dropped. If you have an RPM meter on your car dashboard, you can watch this occur. Your car will jerk if the RPMs don't immediately match up with the speed your car is going at the new gear. In order to avoid the jerking, you must create the smoothest transition between the torque of the engine to your wheels. Shifting from first to second gear is the most susceptible to that telltale jerk. This is because the difference in gear size ratio between the two gears is the greatest, requiring a greater precision in timing to execute smoothly.
Perfecting the Timing
You can tell whether your RPMs are falling too fast or too slow by how the car jerks. If it slows suddenly, sending your body forward, the RPMs were too low. You should try shifting faster or applying a bit of gas to bring the RPMs back up. If the car surges forward, pushing you back, the RPMs were too high. Try waiting longer for the RPMs to fall more before letting go of the clutch. Slipping the clutch, allowing for some friction between the clutch plate and flywheel, also might help. The more practice shifting between gears, the easier it will be.
If your automatic car is jerking while changing gears, you have a maintenance rather than an operation problem. Check the transmission fluid levels. If that doesn't help, something could wrong with your transmission itself. Your mechanic could diagnose the specific problem.
Juliana Torres started writing in 2004 for "The Daily Texan." She was an intern at "People en Español" and "Texas Monthly" and co-authored the book, "A Legacy Greater Than Words." While writing for the "Osceola News-Gazette," she won several Florida Press Association awards. Torres earned a Bachelor of Journalism and a Bachelor of Arts in Spanish from the University of Texas-Austin.