Bad shaking at speeds 50+. Tires? Suspension? Alignment?
 

I recently installed new drop springs and struts. I also rotated my tires from front to back. Following the install I have been experiencing a shaking in the steering wheel at different speeds over 50 MPH.



Thinking that it was alignment I took it in to have the standard post-suspension install alignment. Long story short, I did not have it done, but when I mentioned that I was having steering vibrations they said that it might be a balance issue in my tires. I had purchased a lifetime balance option when I bought the tires so I had them re-do the balance on the tires.



When I picked it up they said that 3 of the 4 tires were out of balance so I assumed that things would be fine.



Prior to the re-balance I had a shaking @ 62-68, then again over 74. Now I get a shake at closer to 52-53 and extending up to the high 50s, then again @ 62-63. It is really frustrating.



So here are my questions-



If before the suspension install I had no problems, and now after the install I do, is there anything that might be installed wrong that could contribute to the shaking?



Should I have the tires rebalanced again? If so should I take it to another shop?



Could it be the alignment that is causing the shaking?



Help! I have to take a roadtrip next weekend and I would really like to have this sorted out before I drive 1000 miles...

Rotate the tires back how they were. If it gets better, one of the tires has a bubble, separating belt or flatspot.

Do you have aftermarket wheels on your car? Did you install hub centric wheel adapters if your wheels have a larger bore than the hub? That can cause shaking or vibrations like you mentioned too because the wheel isn't sitting correctly up against the hub.