The arm on my upper engine mount can swing back and forth in the bushing. Is this normal? I'm not sure what a good one looks like. I've seen the one's IPD sells and they look pretty stiff and looks like they may cause some engine vibrations to enter the cabin since they are made out of polyurethane. Is this true? Am I causing any damage to the car if I just leave it for now? Does anyone else make a "heavy duty" rubber, non polyurethane bushing?