Strange Buzz when on track
 

I have an 01 FMII Miata that I recently purchased. I brought it to VIR last week for the Chin Motorsport track day.

I noticed a loud buzz or rubbing sound coming from the middle of the car that I've never heard while driving it on the street. It almost sounds like the down pipe is buzzing against something. It takes a lap or so of hard driving before it shows up. The buzz is continuous; however, the sound of the buzz changes while one the throttle compared to coming off the throttle. It almost sounds worse coming off the throttle.

The car does not make the sound when driving on the street; however, I can duplicate the sound if I get on it really hard for a few minutes.

Has anyone experienced anything similar? Any ideas?

Thank you,

Greg

in for response.

if you have polyurethane diff bushings it's might be the resonating of the drive train. i get a nasty mid car buzzing from my 01+ car with poly bushings.

Check downpipe for clearance. If it's < 1 cm anywhere - fix that.

johnwag's car was buzzing from the down pipe also, begi has these for that

BEGi-S Miata Motor Mount Spacer 90+ BEGi

Thank you very much for all the help!