Ok, what I would think to be a really odd sort of problem.
Good old RB20DET gearbox, its got brand new bearings in it, and when all that happened the sincs were also deglazed, and in general I was given a gold medal for my gearbox (selector broke, hence the semi rebuild, much cheaper to do both at once). So going by that its is NOT sincs.
Anyway, the problem is the gearbox is horbile until the car is warm (ie, 30mins or so of driving) and the gears mostly 2nd & 3rd crunch rather badly, more so 2nd on down shifts. (3000rpm, will not go in to 2nd at all). You can all so feel it being a bit notchy on the other gears.
Then once it is warm, it will do whatever I like fairly easy. Still isnt too keen tho until about 1-1.5hours of driving.
So, today the gearbox oil was changed, this makes the changes smoother once its warm, and the whole feel of the box better, but didnt do bugger all to stop this crunching.
So my question is, what the hell could it be!?