Earlier this year I replaced the very rusty exhaust on my 05 FXT with a TurboXS turboback kit. It was fabbed up to work with the metal support tab that connects to the transmission just like the stock exhaust. I guess it's there to put less strain on the turbo? At any rate, the original bolt didn't survive so I went ahead and installed the exhaust without actually bolting that support up. I finally got fixed last week and I've been noticing a buzz/whirl/hum, especially on the highway. I'm having a difficult time associating it to engine, transmission, or wheel speed (especially over the actual exhaust). But unless I'm having a wheel bearing go from 60-0 in like 100 miles (in my experience they take a while to _really_ go bad) I'm thinking it might be from the exhaust. Anyone else encounter anything like this? I tried to snap a pic with my phone. Don't mind the rust—that's a project for later this year.
Was able to try and dig into it yesterday. Don't think it's exhaust related, just coincidental. Dug out a small rock that got wedged by a brake pad but that wasn't the noise, unfortunately. Both rear hubs seem fine and the rear diff has fluid in it. ¯\_(ツ)_/¯
Vibration is a tricky customer, since it happened right after you got it fixed, makes me think something (possibly your exhaust) is now resonanting enough that you notice it. Changing how a part is mounted, by ironically fixing it, could easily shift the frequencies your exhaust vibrates at. Easy way to tell would be simply removing the bolt and seeing what happens. You might have had the bad luck of picking an exhaust with a significant resonance at your car's natural frequency(s). Probably can't hurt to change the tranny oil, but since it was there as soon as you got it fixed makes me think that's not your culprit.
Ended up being the rear LHS wheel bearing. Same side as the exhaust. Still at a loss, when I've had them go out in the past it's taken a few hundred miles to really settle in and be noticable. This one went in under 100 miles.
