[GrungeTundra]

I just cut some pieces out of some foam flooring like they use in weight rooms and I'm about to take it for a drive. I don't know if this is related to the "harmonic frequency" issue but I've noticed that when I drive over speed bumps at 10 mph or higher the back end reverberates for a few seconds after the back wheels have cleared the bump so I'll try the speed bump test also.