Hi all,

I have a 2008 GT with ~ 127K miles. I've been having this strange problem for a bit now where when making a left turn (moderate to tight) there is this very low frequency sound (25-30Hz or so?) and vibration.

• When it happens it is a constant tone; not cyclical.
• I can't tell if it's coming from the front or rear.
• It happens when travelling around 10MPH or higher.
• It doesn't sound like the typical LSD clutch pack howl noise that are common with these cars (I experienced that with my 05, but not with this 08).
• It sort of sounds like when you drove over one of those metal-grate "green" bridges.
• I don't notice any handling issues.
• The car is lowered (Steeda Sport Springs), but it's been that way for many years.
• I have summer performance tires (245/45R-18) which I have had for about two years now. I have inspected the tires and they seem to be in good shape (I don't put too many miles on).

My thoughts:

• Wheel bearing? I am skeptical, since I don't hear any howling during normal/high speed operation that I would expect to hear from a worn bearing.
• Tire rubbing? Again, skeptical. I feel like I would be able to see some signs of rubbing. The car sits evenly, the camber/castor looks normal, and I don't see anything close to causing clearance issues with the wheel turned.
• Differential? I did change the fluid around two years ago (royal purple + the Ford friction modifier). Never seen any leaks. This problem was not happening for probably 1.5+ years later. Also, it seems strange that the issue is only for left turns. I have tried a lot to replicate with right turns and it's never happened.

When I get some time, I plan on jacking it up and having a closer look. If all else fails I'll have my local shop take a look, but I'm curious if anyone here has any thoughts.

Thanks in advance!