Alright so i have a b18c(R) in my 1995 integra that i have completely rebuilt. Flywheel resurfaced, brand new exedy stage 1 clutch and the transmission was rebult by sean previously from Innovative Motorworks (Carlilsle, PA). My third and fourth gear is currently girinding at high RPM. 3rd, 4th, and 5th syncos were all replaced, had carbon syncros before that were beat to hell and back do to the privous driver lol. WHY would it be grinding.. below is everyhing that is new...
Slave Cylinder
SS Goodrich clutch cable
Master Cylinder
Transmission rebuilt with OEM syncros
Exedy stage 1 clutch
OEM ITR flywheel resurfaced
Clutch adjusted via engagement with the master cylinder rod to pedle.

WHAT IS GOING ON!!!

 

I feel like there may be some info missing from this story..

But, just to throw in my 2 cents I'm curious about the oem synchros. I have had many of these not want to grab even though they were in good condition along with the hub and slider. But realistically it's just going to be an internet guessing game as to what's really wrong.

 

Did you replace the 3rd/4th hub and sleeve? If not take a look at it. Synchros alone are rarely responsible for a grind. Personally I would have put carbon synchros in it again, I find they hold up a lot better if you're driving it hard.

 

Did they replace the synchro springs when they rebuilt it? This is generally the first part responsible for a grind, as the spring does not apply adequate force onto the synchronizer to slow it down, resulting in a "grinded" shift. As 94EG8 said, the hub slider needs to be inspected for damage, along with the gear engagement dogs. If these do not have a proper point on them, engagement may be difficult. The three sets of points on the slider must engage the synchro spring for it to apply pressure onto the synchronizer.