It vibrates when going between 30-40 mph. It doesn't do it with higher speeds. Feels like running over deep rumble strips. Multiple times when I'm driving in town. Feels like it's underneath the back.
My car has 101000 miles.
My car has an automatic transmission.
Hey there. This could be due to a torque converter imbalance, or internal problem with converter, which will sometimes occur in a dynamic and limited range. Have a technician attach wireless "chassis ears" to logical areas on the drivetrain to narrow down the possibilities using this technique. There are also harmonic diagnostic tools, which will pick up the frequency of the unusual noises you are hearing, and translate it into more likely mechanical causes. Different types of part failures create unique frequencies that can be decomposed by this tool. If you would like to have this done, a certified technician from YourMechanic can come to your car’s location to diagnose the vibration issue and pinpoint what should be repaired.