In the last few days there has been an intermittent high pitched whirling noise coming from the rear undercarriage of my 2009 Elantra with automatic transmission, at least it seems where it is more pronounced on the outside of the vehicle. Has anyone else experienced this before and possibly know what may be causing it? The pitch is unaffected by acceleration or climate control changes. It just comes and goes at random. The temperature here has dropped considerably in the last week or so and seems to have started since then.