The clue here is the problem just started with the new axle shaft. Get it replaced under warranty. Rebuilt half shafts are common but very often a worn inner cv joint housing is overlooked. A new housing from the dealer costs about three times as much as a rebuilt half shaft so buying a new housing isn't practical.
I can go into detail about how to inspect the housing because the wear is not real obvious, but I'm pretty sure that's the problem. The typical symptom is a steering wheel shimmy up to about 35 mph but only under load as in accelerating out of a parking lot onto the street. That shimmy is often worse when turning.
It's normal to have up and down play between the inner cv joint and transmission. The rate of rotation is one third of a rear-wheel-drive drive shaft so vibration isn't a problem.
Tuesday, January 31st, 2012 AT 5:56 PM