After taking my car to the track and launching at about 3k rpms, i now hear a noise comming from my rear. I can only hear the noise when i am turning left or right. It is easily heard when i put the engine under load (going up my driveway hill), and going very slowely (<1mph) it is heard as a loud "bumping/ rubbing/" sound about twice per second. It does not happen when the car is in neutral and there is no load on the drivetrain.

my friend said it may be a blown bearing somewhere. any ideas???

 

update: sound does not always happen. After i take it to the track it gets loud.

 

Let me guess, the sound is gone when the car is cold, but after you drive awhile, it comes back.
Check the alignment of your gears, you may have lost a clip or torqued 'em...

 

car was in the shop and they opened up the rear. He said he didn't see any metal grindings in the oil, so i assume there wasn't anything too obvious. i'll look into this further, thank you for the input.

 

do a burnout and see if you are laying two strips of rubber. Do a few little ones to make sure. If you mostly get a one tire fire, then the diff is most likely shot. Don't be surprised if you only spin one every once in a while becasause it WILL happen everyonce in a while.