Ive been helping a friend work on a 2001 s2000 that had a grinding noise. The noise sounds like gears that are not meshing its quite loud. The problem occured while he was doing doughnuts in a parking lot the car had huge 19x12 tires on the rear with all stock parts other wise. after he had finished the car would no longer move and made the noise. Wich sounded like the diff had failed.We took appart the diff and it was intacked. It was replaced with a comptech diff that was knowing to be working. Started the car and as long as there is no load (ie. on jack stands) on the tires it would go through all the gears. As soon as you put any acceleration to it the grinding came back even on the jack stands.
We then rip the motor out took the tranny off, drained the tranny oil and there was no metal even running a magnet throught it. The clutch was bad. it was bad before he did his doughnuts. When we took it apart the throw out bearing runs out about a 1/8 inch from its highest to lowest points, the whole clutch disc was blue from heat, and the fly wheel was gouged and glazed.
we replaced all the parts and still does the same thing. the noise is less but it is still there. I had notice that the the clutch fluid was black. and the slave cylinder didnt want to bleed and i had to take it off and pump it by hand to get it to work. when i did that it blew a bunch of black gritty fluid back out.
So my qustion is could the tranny had gotten hot enough to cook the oil and cause the slave or master to fail, and would that cause the grinding noise. It is blowing my mind as to what could be wrong with this thing. and help or input would be apprecaited
GRAF-FITI loves you 
