Mps350z

Whenever Im driving and I have to shift into 5th while my RPMs are high, or just shift into 5th quickly, I get a grind... not so bad under normal driving conditions and I just shift quickly... but when the RPMs are high and I really slam it in there the grind is significantly worse. I think its my syncro Im going to get a transmission flush and use better fluid but I dont think thats going to make it any better. Has anyone else had this problem??? does anyone know how much this would cost to fix??? would I be better off going to the dealership(it's not under warrenty), or going to a private shop? Thanks in advance.

locknut

i am having the same problem, my old tranny was grinding from second to third which as i understand it is a common problem in the 03 models....so i had the tranny swapped out got the new w6 or w8 or whatever it is and less than 5000k into this tranny it has started grinding going from 4th to 5th th but it only happens when i am on the highway doing about 170kmh and switching quickly...normal driving doesnt seem to happen....took it to the dealership they said ohh it could be just tranny fluid and the synchros arent alligning up or some darn excuse they flused it and i noticed a little difference but i have had 1 occurance since then.....kinda disappointed with 350z trannies....i am sure i will have to rip the tranny out this winter and redo the synchros, as i am not under warranty...well thats not entirely true i boought an extensive extended warrenty from third party i might be using some of their money to replace it....we will see?