I have a 2003 WRX running about 300 horses to the crank with a bone stock tranny. I noticed that it has slowly been grinding when shifting from 4th to 5th gear. It NEVER grinds when the car in not completely warmed up. Only when I have been driving for about 20 minutes or so does the grinding from 4th to 5th begin. I also notice that it grinds most under a heavy load (climbing up hills, speeding, etc.)

Does this mean that I need to get my syncros redone? Any help would be appreciated. If my syncros need to be replaced should I just have the RA gear set added in order for this kind of problem not to occur again?

Thank you,
David

 

Change the lube....

Try my cocktail....

1qt GM Synchromesh
1qt Redline lightweight Shockproof
..and the rest, to fill, 75w90 Castrol HypoyC gear lube.

Works wonders on 5MT Subie trannys.

 

Would changing the lube fix the grind going from 4th to 5th??? I am about to spend over $4,000 on a complete tranny rebuild with new clutch, flywheel and RA gear set. Is this necessary, or do I just need to change the lube?