when I shift at high rpm 1st gear to 2nd gear, it grinds.

How much to repair?

 

Free, push the clutch down.

It may be tranny fluid. Replace fluid with Redline MT-90. Do not use Royal Purple

 

could also be your synchros. i had the same problem. its caused by pulling back to hard on the shifter usually occuring during aggressive shifting

 

how many miles on your 8?
Are you using OEM fluids?

How long has it been grinding for?
It could be an issue with the synchros OR.... it could actually be your clutch pedal. If the pedal welds are flexing then the clutch isn't engaging properly and you'll grind. Look at NYCGPS's thread on his clutch pedal snapping and you'll see which welds can be affected.

Also, the pedal is adjustable, you might check to see if that helps.

 

rx8 2004 winning blue
92 500 miles

the clutch have been changed this summer
but had less resistance than before the repair....

it grinds since 1 month...

 

How badly does it grind? If it's only a bit, change the transmission fluid with a synthetic as suggested and perform the shift a little slower and more deliberately.

 

at 94xxx miles you better start looking for a used replacement, it's your best cost option