Originally Posted by Beepster
I will assume you are talking to me,so I will reply.
My car as a pulsating noise and vibration coming from the front of the car between the speeds of 50 and 70 MPH.Only a few cars have the issue.
I had a 2005 Mazda3 that had a similar sounding problem. In our car, the drivetrain would shimmy at 50-70 - similar feeling to a wheel balance problem, but a higher frequency vibration. We could feel the vibration from the front of the car, but also through the shifter, and only under load (not coasting). It didn't matter what gear we were in, and a different set of wheels didn't make any difference. In our car, the problem appeared in its first year and gradually got worse over time. Changing the motor mounts (as per a TSB) made a mild difference, but didn't solve the problem. We never went as far as asking the dealer to change the axles or transmission. We loved the car, but finally sold it at around 60k because I didn't want to deal with it any more.
My thought is that the engine mounting design for the 05 Mazda3, while very good at isolating vibration, might be somewhat prone to oscillation if there are minor imbalances or out-of-tolerance parts. The Mazda3 motor mounts were FoMoCo; maybe the 2012 Focus design has similar issues?