steering wheel problem

i have 94 civic hatch and i just put some ground control and tokico blue shocks on and now all of a sudden my steering wheel starts vibrating when i hit about 40+ miles per hour...now i know my axle is going because its making a slight click when i make left turns but not when im driving normally and its not shaking when i make any turns, so the question is what could possibly be making my steering wheel vibrate vigorously when im driving straight, my main thought is the axle but before i go and get one and that not be the problem i thought would get some feedback from u guys (also is it true that making fast u-turns can assist in destroying your axle)

alignment dude!!!!!!! when u lower your car, ur alignment gets messed up pretty bad. u gotta go to a mechanic/shop and have them do a four wheel alignment on your car. should be about 50 bucks! and how much did u lower your car by? if it's over 1.7 inches then u need to get a camber kit as well

He's right, --- alignment.