What else can cause shuddering/vibration?

[Jand3rson]

I've been getting a very light, rhythmic shudder/vibration in 3rd and 4th gear, when I'm really pushing it hard, like on the highway. I know it's not the driveshaft, because I just did that job over the summer, and it's been fine since then. Plus, that's not usually the rev range where driveshaft vibration happens.

I suspect that maybe it's because my car is out of alignment (didn't have one done when I installed my suspension). My biggest suspicion is that it could be possibly one of my wheels is bent, from the little spin I had a few weeks ago, that put my rear wheels up over a railroad track.

Any other suggestions? I know the first thing I need to do is get my car in and get it aligned, maybe I'll have the rear wheels checked out while I'm there.

[nickmp0wer]

maybe its becaues the back wheels are out of balance. Mine are and my whole car shakes like im running over those groves at the side of the freeway when i go over like 90. You could also probably just jack the rear up and start the car in 1st then look at the spining wheels to see if they are straight

[Jand3rson]

maybe its becaues the back wheels are out of balance. Mine are and my whole car shakes like im running over those groves at the side of the freeway when i go over like 90.

That could be, they haven't been balanced since we bought them originally for my wife's E30 about a year ago. I didn't even think of the wheels being out of balance.