Vibration on different road surfaces

Hi Dave and thanks for using 2CarPros.com.

If I understand correctly, regardless of road surface, you get a vibration near seventy mph. If that is correct, the first thing I would suggest is having the tire balance checked. If you feel the vibration in the steering wheel, most likely the front tires (or a bent wheel) are the issue. If you notice it more in the body of the car seat, most likely it is related to the rear wheels.

If you have already check tire balance and made sure there was not a bent rim, I would next check for a bad universal joint or even alignment.

I do not know if this will help or you need it, but here is a link which shows how to check a universal joint. As far as tire balance or alignment, you will need to have that done and checked. Please keep in mind, a worn steering component can also create a vibration. However, all steering components and suspension components should be check by the technician prior to doing an alignment. One last thought, if the tires have worn unevenly or have a shifted or broken belt, that can be an issue, too. However, I do not feel it would only be limited to high speeds. More than likely, you would feel it at any speed.

https://www.2carpros.com/articles/how-u-joints-work

Let me know if this information is helpful or if you have other questions.

Take care,
Joe