My Sienna starts vibrating at ~55 mph. It hits a max amplitude at ~65 mph. Because of the speed-dependence, I suspected something rotational. I’ve replaced the tires and wheels (temporarily) and the front axle assemblies. There is also a bit of thumping going on when I apply the brakes easily. Could this be some imbalance in brake rotors or drums? Any other ideas?
We have a similar problem on a 2001 Sienna we are waiting for the results of a Drive Train diagnostice from Toyota. It was determined it was not the brakes or the tires. Will update any new information.