Brakes? But if it were brake rotors, it would do it while you apply the brakes. Not all the time.

Some of the ball joints are under tension while the car is lifted on stands. If you have ramps, then the suspension will be compressed like it would be on the ground. Maybe THEN you can find something loose?

Another possibility is loose axles (loose CV joints). Probably would make some noise, but we're running out of other possibilities. Put the car up on ramps, grab each axle, & try to wiggle it. Most of the time, that would cause vibration only while accelerating.

Another thing to try...
Find some place with a Hunter GSP9700 wheel balancing machine. That can measure uneven road-force which might(??) be caused by certain layers inside the tire moving around in ways that aren't right. Separation between belts would be a tire defect that comes on slowly & subtle. Sometimes drive you nuts trying to figure it out, until eventually the tire comes apart.

 

Thanks again Jim!

The brakes are warped and do shudder when I brake. I just ordered Powerslot rotors and Hawk HPS pads about a 1/2 hour ago.

Loose axles, eh? Could be a possibility, I had both replaced (at different times) @ Meinike.

I know it is not the upper balljoints, as I just installed an Ingalls balljoint camber kit, and it was shuddering before that.

The tires are relatively new. They are Yokohama WS4's. This is only the second summer I have driven on them as they are my summer wheels + tires.

I also will be ordering some Tokico Illumina struts tonight and replacing them next week hopefully.