I took my GTO in yesterday to repair the problem I outlined in my "Loose Suspension" post (a rattle that turned out to be caused by a torn rubber bushing on the front anti-roll bar).
Wow, what a difference! I now realize that my car has been a bit noisy since I bought it in March, but not knowing any better, I just figured the occasional rattles over bumps were normal. But they got so bad in recent days that I knew something wasn't right, and it wasn't.
It was such a weird problem. I asked my service writer if I could look at the suspension once they had the car up on the lift, and he let me. The problem was on the passenger side. At each end of the sway bar there's an upright rod that ties into the strut. The rod goes through a bracket, and on its way upward it passes through a washer, the rubber bushing and then the metal of the bracket. The rubber bushing is about the size of a silver dollar and about as thick as a pancake. Somehow, my bushing had blown out one side, making a letter "C" out of it. The washer had worked its way through the bushing, resulting in the bushing and washer actually swapping positions, with the metal washer making direct contact with the bracket--hence the noise.
But now all's well, and I have the tight, rattle-free ride I should've had right from the start. What a cool car.