Had a track day event this past weekend at VIR. I was scheduled to run four-25 minutes sessions per day but on my third run on my first day, on hard braking/down shifts and especially on right turns, the car started making vibrating noises under my feet. The instructor and I noticed it at the same time. I jacked it up to see if my downpipe was hitting something or the exhaust broke loose, like a missing hanger or a busted clamp but everything looked good. Drive shaft and the u-joints - OK. Suspension components - OK. Wheels and bearings - fine. I cannot recreate it on the road and it looks like it only can be recreated during track conditions with high heat, speed and G's.

I eventually packed up after the 4th run because it only got worse and went home pissed off because I could not find anything obviously lose underneath and didn't want to risk anything. Any ideas or similar experience? I'm going to pull the down pipe to see if it's that hitting against the transmission tunnel.

 

Wheel balance, thrown wheel weight? broken motor mount?

 

WORMS?

Sometimes I can get SERIOUS worms on my tires at VIR. I have had a similar feeling several times on different cars.

 

Imagine the exhaust banging against something real fast. That's what it felt like...that's probably what it is. Jeremy @ FM said it may have been that my rubber hangers got hot and more pliable causing the exhaust system to swing around more.

Suggestion is to get poly hangers and replace the diff mounts. My engine mounts are already Mazda comp units with 3K miles on them.

 

Sounds exactly like my downpipe...

 

Are you using adjustable swaybar endlinks? If so, the swaybar may have moved all the way to one side, forcing the tire to contact it on right turns. My RB bar did that, until I recentered it and put rubber sleeves and hose clamps on the bar to keep it centered.

 

rotors?