sammon287

Under a specific harmonic frequency under acceleration, I get a metallic buzz/rattle from under the car. It sounds like it comes from the passenger side cat converter area. I thought it was the heat shield, but that seems very secure. I have flowmaster mufflers which I have heard are prone to internal rattles, but it really sounds like it's from the front of the car. The other reason I think it's exhaust related is that it becomes less pronounced when the car is hotter. It's an 07 GT with only 14,000 miles. Are the factory cats known for internal rattles? Anything else to check out down there? I'm limted on room with some plastic ramps.

bigmike06gt

I have the same kind of rattle in mine right around 3000RPM when the car is cooler. Ford told me my passenger side Cat was shot, a baffle or something broke loose(not sure what is in them). Mine has been that way since I had around 25000 miles and now I am at 75000 and other than the rattle it doesn't hurt anything.

jrockgts197

Could be the separator plate. Click here

There are 14 pages if you want to read them all. If not, the solution was found on page 12 or 13. There is a separator plate between the bell housing and the motor that vibrates. I had this same issue and fixed it with the rubber washers.

Here is the TSB.

sammon287

Thanks so much. That's the sort of info I was looking for. I never heard of that.

Nuke

Another long-shot is to torque the exhaust clamps about another 1/4 turn or so. There have been a number of issues with clamped joints.