A transmission mount, much like an engine mount, is designed to keep your vehicle's transmission system in place. It also performs a number of other functions to keep your vehicle from falling apart.
The mount works in conjunction with the engine mount to control torque and vibrations in the vehicle. It reduces the amount of vibration transferred from the engine bay to the chassis as well, so the ride is smooth for the driver and passengers.
Also relying on the transmission mount for stability is the driveshaft, which is an extension of the engine's crankshaft that runs through the transmission to the rear axle. The driveshaft is responsible for delivering power to the rear of the vehicle. Rear-wheel drive vehicles require a longer driveshaft to send enough power to the back wheels.
In most cases, the mount is located underneath the front end of the vehicle's frame on the driver's side, which exposes it to the elements - such as rain, snow and dirt - that can lead to damage and wear.
If the transmission mount breaks, it will cause a loss of stability in the area surrounding the break point. A broken mount will be unable to absorb the driveshaft vibrations and you will notice that the passenger cab is not only experiencing vibrating sensations, but can also get pretty loud when traveling at high speeds.
Since the mount is designed to support the transmission system, which tends to be heavy, a break can damage the system's housing.The instability will create unexpected strain on the housing and unsupported transmission weight can lead to a cracked or otherwise damaged housing. The transmission mount can break in multiple spots at once as well, which can cause damage to a number of different areas in the housing and other aspects of the system.
Since the transmission system relies on the mount to keep it properly in line with the driveshaft, a broken mount cal also cause misalignment. The transmission housing needs to be positioned in a certain way to ensure that the driveshaft can enter it and access the gears properly. Misalignment can cause damage to the driveshaft and the coupling that connects it to the transmission.