ihealy16

I have a 2010 c6 6 speed manual base coupe with 22k miles on it. Its a fully loaded 3LT with Mild to Wild NPP exhaust from factory. The car has a tendency to chatter a bit for 2 to 3 seconds shortly after start-up and then goes away. That is the only time I hear this sound. My question is what could be causing this rattling/chattering noise because I know this cant be normal. I've tried to pin point where its coming from and it seems to be either under the car or somewhere near the rear of the engine/transmission. Other people have described it is metal shavings being shaken in a can very fast or a metal baseball card in the spokes of a bicycle. I thought it might have been the heat shield or an exhaust hanger of some sort but wouldn't that cause it to rattle all the time instead of for 2-3 seconds each startup. Any suggestions and things to look for would be greatly appreciated. If anyone has had this problem please let me know what the solution is!
Regards, Ivan

ihealy16

Moderators please move this thread to general discussion. I accidentally posted it here. Thanks

tslsa28

I have the same issue and I think it is the inside of your mufflers. There are baffles and parts inside that might come loose. If I start mine with the NPP fuse removed (always in loud mode) I don't get the noise. Try that and then you'll know it's a broken muffler.

C6topless

It could be your torque tube.

extrapilot

The drive shaft inside the tube will not be turning if starting in gear, and obviously with the clutch depressed.

ihealy16

I have heard many people complain about the baffles inside the NPP exhaust coming loose. However would that still apply if I had the mild to wild remote? because it happens in both open (loud) and closed (quiet). Could it be that the system briefly opens and closes when you first start the car. If so would pulling the fuse be the only way to check if its the baffles inside the NPP exhaust causing the chattering/rattle noises. I've been paying more attention as to where the sound is coming from and it does sound like its somewhere in the back half of the car.

ihealy16

What are the symptoms of a bad or starting to go bad torque tube. Because the noise only happens for a couple of seconds MAX shortly after startup and that is the last time I ever hear it...occasionally when the engine is already at optimal temp from a long drive and I shut it off to run into a store or something and come back out after an hour or so and its still somewhere near optimal temp I wont hear the noise when I start it.

extrapilot

With only 22k miles, I would doubt you are having issues with the TT.

Listen to this one. Sounds like the bearings are going bad in this video.

ihealy16

I don't think it sounds like this. To me it sounds like someone took the little metal piece off the top of a soda can and shook it around inside but then again I've always heard it from inside the car because I don't have anyone to start my car for me. I do have a GoPro that I will use in a similar fashion as the youtube video and post it up so maybe we can get a better understanding.

extrapilot

Yeah, a video would be great...

ihealy16

***Repost*** (not sure what happened to original video.) Ok so I finally got around to filming the noise. Sorry about the delay but work has been pretty crazy these past couple of days. The filming was done in two days and then I had a whole bunch of editing problems and software crashes that pissed me off and delayed this even further. All start ups are on a cold engine. The first pair is on the first day and the second pair is the day after. Link is below. working on filming some better footage with less exhaust sound, unfortunately this week is full of rain here in dallas

extrapilot

Seems to make the noise only when the flaps are closed, so I'm thinking that there is more back pressure inside the mufflers and a loose baffle could be rattling a bit. Mind you this only a guess on my part.
Moving the camera around under the muffler at different positions would help with capturing the rattling noise since the exhaust note is over whelming it in the audio of the recordings.
I certainty don't here anything related to the Torque Tube bearings, though.

ihealy16

The noise happens during both modes. It just much more noticeable when flaps are closed. If you use headphones the sound is much more apparent in both modes. Ill see if i can get the camera under the car closer to the transmission to muffle out the exhaust more.

ihealy16

Bump still looking for possible answers for noise and solutions to the problem. Also trying to put up better sound captures of the rattling. However the weather here in dallas isn't exactly helping with all this rain.