I just recently noticed a heavy vibration when accelerating. The thing is, its really light to almost not there when I hit the gas, but from 55-60mph its horrible, then after 60 it goes back to a very light vibration. I just installed new rotors a couple weeks ago and when putting everything back together I tightened all the bolts to the correct specs, but whatever happened could have happened before I installed rotors as where I live, I don't normally get to reach speeds that high. I'm hoping this is just a balance issue but I wanted to see if you guys had any insight to give me. Thanks in advance.

 

Did it happen at the same time as the brake job or you just noticed it at that time? First thing i would do is try rotating the front tires to the rear and see if it makes it go away or less noticeable. Things that usually cause that are Wheels (bent or out of balance), Axle. or motor mount.