Got no help in the suspension/chassis forum so here it is..

Just like the title says, the front wheels start to shake violently but only when im going 40-45 mph. If I go any faster or slower it stops?? I know it's the wheels shaking because a friend of mine was riding in his car and could see them shaking, and the steering wheel shakes violently while it's happening.

I lowered the car on intrax (2") springs a couple hundred miles before this started but I'm not sure if or how that could have caused this.

What should I begin looking for?

 

check all your steering components wiggle up and down side to side. check all sway bar bushings and bolts. you may also want to get a strut tower brace and wonder bar. also check to see if your wheel weights are still there if not then tires could be out of balance. all these things and more i am sure could be behind the problem but start there. hope this helps.

 

Did you get an alignment after lowering the car? It seems that you are setting off a natural resonance at 40 to 45mph. As stated above, check all suspension items.

 

I had a similar problem with a Chrysler Concorde. I jacked each front wheel up so that it could be moved freely. I squatted down and put one knee on the front sidewall and one knee on the rear sidewall. I grabbed the tire from behind the tire at my knee positions. Then I moved left and right to put pressure on the tire. The problem became obvious because the passenger side wheel easily banged back and forth. I further investigated by watching under the hood as I wiggled the wheel. On this particular car I found a rubber bushing that had completely fallen out thus creating excessive 'wobbling'. This wobbling only happened at ONE place but it was consistent: leaving a specific bank and turning left as I did so. At no other time would it show up !! When it did show up it felt as if the pavement had a very excessive wavy pattern up and down. But my problems was actually caused by side to side movement.