The car has 123k on the original motor and trans. Overall it runs good but the trans feels a little crappy at times. Sometimes gears are tough to get into and bounce when i go to put them into gear. Tonight i was reving high and went to go into 3rd and it didnt slip into gear correctly and bounced when i went to put in, and grinded BAD. First of all how bad is grinding periodically like that and also what could have caused the problem besides me just possibly missing the gear.

 

The obvious answer is that the synchros are going. Otherwise, it could be the master clutch cylinder. Check for leaks under the clutch pedal, and the level of the clutch fluid. Also, try doing a transmission fluid flush with Honda MTF. See if that helps...

 

Your synchro is dead

More the rev is high and you shift fast more the grinding noise is evident.

try gm synchromest or castrol 75w90 syntec it may help