Transmission issues can be some of the most costly and serious problems you'll have with your car. Luckily, most transmission troubles are progressive. That means that if you recognize the early signs, you might be able to catch a problem before it leads to complete failure. When it comes to automatic transmissions, hard shifting is one of the most common indications of a problem. If your transmission isn't shifting as smoothly as it used to or your car bucks a bit every time it shifts, that's a sign of a potential problem. Here is a look at some of the things you should check if your car's transmission is shifting hard.
Inspect the Transmission Fluid
The first place to start with troubleshooting a transmission problem is the fluid inside the case. Sometimes, hard shifting is caused by insufficient lubrication in the transmission. The shifting process is harder because of increased friction between the gears. Your transmission should have a plug or dipstick for you to check the level and condition of the fluid. Look at the level and make sure that the transmission is full. If the level is low, add some fresh fluid to the case and then consult a professional, like Terry's Transmission, about the source of the fluid loss. If there's sufficient fluid, look at the condition of it. It should be translucent and red in color. If it's darker, cloudy or full of debris, you need a transmission flush.
Check the Error Codes
If the problem in the transmission isn't the fluid, it may be one of the sensors. The transmission control module will send an error code to the car's computer if there's a problem with any of the sensors or other regulated systems in the transmission. Luckily, you can have the car's computer scanned for error codes at most any mechanic's shop or auto parts store.
The speed sensor is a common source of trouble for hard shifting. If the speed sensor is failing, it could be relaying that the car is moving more quickly or slowly than it actually is. This could cause the transmission to shift at the wrong time, causing a hard or difficult shift. The car's computer will release an error code if this sensor is failing.
Test the Vacuum Lines
If you've eliminated the fluid and the sensor error codes as issues, you may want to have the vacuum lines on your transmission tested. If the vacuum lines are clogged, disconnected or bent, it will disrupt the necessary balance of the vacuum needed in the transmission for a smooth shift. A transmission repair technician can test the vacuum lines and clear a clog if there is one.