My car is a 2000 m6 ss. I’m getting a weird sound when I’m taking off from a stop and when I load the engine while driving in gear. After driving more today it is definitely a grinding sound. I was certain something was hitting the drive shaft, jacked the car up, got underneath and saw 2 grooves in the drive shaft where it has hit at some point. I put the car on Jack stands to simulate a load as if it was on the ground at normal ride height and I can’t see anywhere that the driveshaft could come in contact with anything in these 2 areas. The driveshaft has signs of contacting something but I don’t see any where else that would indicate it’s the object contacting the drive shaft. Full disclosure i bought this car used and it has a newish poly torque arm bushing so it’s possible that the bushing was bad before and the driveshaft was contacting the torque arm previously leaning those marks. The noise is definitely a grinding noise though and it sounds bad. I just had the rear end done for a separate whining noise (found out someone didn’t set the rear end up properly when they had it apart) and it was there prior to and after getting that taken care of. It is definitely coming from underneath the driver area and not in the the rear of the car. It vibrates the whole floor when it contacts and starts grinding. I don’t believe the trans is shifting much because I feel like I would be able to feel that in the shifter. It’s best describe as an aggressive grinding that you can feel vibrating through the floor and is pretty constant while heavy on the throttle or taking off. Also when taking off and you let the clutch out fast so the car kind of lurches back and forth it seems to hit, grind, stop, then hit grind and stop as the car is lurching forward. It’s hard to explain lol. If in gear and you hit the throttle and let off and repeat that, everyone you hit the throttle it makes the noise. It’s constant if you keep the load high enough. Cursing at highway speeds on flat ground and minimal load I don’t feel it. But load it up to go up a hill or what not and it’s there.

Edit: after driving this morning to work I played around some more and it’s ONLY in a forward gear not reverse. So it must be in relation to how the driveline twists in a forward gear

 

the trans mount may be busted. that would allow the trans to lift up and cause binding. its hard to tell by looking at it, best to disconnect the mount an get a jack under the trans an lift a bit to see if its split. if your in shape just lift up on the end to the trans an see if it goes up making it easy to see busted mount. I used to be able to do that but not no more,,, lol. gettin old sucks