A driveshaft is the cylindrical shaft that transmits the torque from the engine to the wheels. They are most commonly found on rear wheel drive vehicles, and connect the rear of the transmission to the driveshaft. As the output shaft of the transmission rotates it spins the driveshaft, which then turns the differential ring gear to rotate the wheels.
Driveshafts are a very precisely balanced and weighted component, due to the fact that they rotate at very high speeds and torque values in order to turn the wheels. When the driveshaft has any sort of issue it can cause problems that can affect the drivability of the vehicle. Usually a problem with the driveshaft will produce a few symptoms that can alert the driver of an issue that should be serviced.
Intense vibrations from underneath the vehicle
One of the first symptoms of a problem with the driveshaft is vibrations coming from underneath the vehicle. If the driveshaft U-joint or bushings wear out, it can cause the driveshaft to vibrate excessively.
Driveshafts are finely balanced before installation to ensure that they do not vibrate. Any sort of vibration is an indication that there is an issue. An excessively vibrating driveshaft will not only cause vibrations that can be felt by the passengers, it can also cause accelerated wear on other drivetrain components, which can lead to other issues.
One of the first symptoms of a problem with the driveshaft is abnormal noises. If the bushing or bearing that support the driveshaft, or the driveshaft U-joints wear out or fail it they can interfere with the driveshaft’s ability to rotate correctly. This may result in unusual rattling, clunking, or even scraping sounds from underneath the vehicle. Any noises such as these are an indicator that the vehicle should be serviced as soon as possible.
For vehicles equipped with driveshafts, they are an important part of the drivetrain and any issues with them can greatly affect the drivability of the vehicle. As they are underneath the vehicle and connected to the transmission, they may be difficult to access and service on one’s own. If you suspect that your driveshaft may be having an issue, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the driveshaft should be replaced.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Driveshaft and was authored by Ed Ruelas.