Sorry for the long read, but I felt the background info was necessary to diagnose the problem. Please help!
My Magnum started to vibrate in a very odd manner roughly a year ago. I replaced the inner and outer tie rods with Moog components. Then I replaced the front rotors and pads. Several months later I replaced the rear rotors and pads. It improved the shaking significantly for a while but never fully took care of the situation. The brakes squealed from day one and never quit.
Fast forward to the end of 2010...
The car was shaking so bad and felt so unstable that I stopped driving it on the highway. I finally took it to the shop and they replaced the inner tie rods and did an alignment. This helped with the "unstable" feeling, but the shaking remained. The alignment is also off a good bit. With the inner tie rods refreshed it was pretty obvious that the front rotors were warped. So, I contacted Glenn and got a set of R1Concepts slotted rotors and Posi-Quiet pads. I just put them on yesterday and headed up to the PA Auto Show in Harrisburg.
The car felt great for about 5-10 miles. Then the shaking came back...stronger than ever! The steering wheel was shaking quite violently and it was definitely speed sensitive. If you hit the brakes it got even worse. We were debating whether or not to take the car back home and grab the Grand Am when the shaking slowly faded and the car was fine again. WTF? I set the cruise at 55mph and after several miles the shaking came back. It went away and came back once more before arriving at the auto show.
The shaking was almost non-existent on the way home, but it did act up for about 8 miles in the middle of the trip.
Some additional points to ponder...
When I took the right front wheel off to change the brakes, I had to beat on the tire to get it off the car. I never had to do this before. This make me think that the shop that did the tie rods did not put the tire on straight. I'm just not sure. Definitely odd though.
I had a difficult time compressing the pistons on the right front caliper too. As for the left front caliper, I believe that it is bad. I took the pads off of the left front and put them face to face (braking surface to braking surface). They made contact on the ends but there was a gap in the middle as if one or both of the pads were bowed (think of it as a cat's eye). I also noticed that the pistons were not the same length. The leading piston (as if moving forward) was out 1/8 - 1/4 of an inch more than the other piston. Both retracted normally.
I do know that the bushing on the tension strut is partially torn. It is not torn the entire way around...maybe half way around. Both sides (driver and passenger) are this way.
So, with all of that... new inner tie rods (again), new rotors and pads (again), marginal alignment... what could cause such violent shaking? And why is it so inconsistent?
I'm getting a really bad feeling that this is going to turn into a money pit real soon.