grinding noise coming from gearbox

[frankiman]

this loud grinding noise occurs when i'm accelerating in any gear, exept for 1st, under 1900rpm
at first i thought it could be rear diff, swaped it out, nothing changed, then the drive-shaft, swaped it out, nothing changed
then i went to see a transmission specialist (hes the only person in canada to rebuilt a Detomaso Panthera gearbox, this guy knows his stuff), and he told me that if it came from the transmission, it could be worn out synchros or the output shaft's bearing, but then withdrew that theory since my tranny shifts super easely (when the super thick redline shockproof oil isn't cold)

and also, just after starting the car, for the first 3 minutes, everytime i depress the cluth on each shift, it feels like a huge "clonk" coming from the cluth or like if the tranny was moving

now my idea is that:
the transmission support is dying and/or
the release bearing is dying and/or
the tranny's input shaft bearing could also be dying and/or
simply, the clutch assembly is f'd up


thanks for any input !!!

[DarkCaporaL]

Are you sure it isn't just low gear resonance you're hearing?

1900 rpm is a bit low to be in any gear but 1st.

[frankiman]

it gets worst as i go up through the gears,
first is fine, second i can hear it a bit
third fourth and fifth is bad

[DarkCaporaL]

it gets worst as i go up through the gears,
first is fine, second i can hear it a bit
third fourth and fifth is bad

You said the sound happens under 1900 rpm.

You shouldn't be in 2nd, 3rd, 4th or 5th gear at that rpm. Every standard car will make a sort of rumbling sound when you are in too high gear for the rpm. I dunno what they call it, but that's why I wrote "low gear resonance" lol.

Unless your noise continues as your rpms go up, but if it's always at 1900- rpm, then that's probably what you're hearing.

[frankiman]

You said the sound happens under 1900 rpm.

You shouldn't be in 2nd, 3rd, 4th or 5th gear at that rpm. Every standard car will make a sort of rumbling sound when you are in too high gear for the rpm. I dunno what they call it, but that's why I wrote "low gear resonance" lol.

Unless your noise continues as your rpms go up, but if it's always at 1900- rpm, then that's probably what you're hearing.

well i used to drive my previous GTR which had bone stock engine/tranny/clutch below 1900rpm all the time and it never made such noise

and i read on rhdjapan about the nismo clutch kit,

Because of the design and manufacturing processes used to create the improved clutch response and increased output provided by the sports clutch disc and lightweight flywheel, it is possible that the transmission or bearings may make a rumbling noise, particularly in comparison to genuine Nissan parts. Transmission or gear noise is most likely to occur at idling or when accelerating or decelerating in the range of approximately 2000rpm; however, this has no effect on quality or performance.

could this be my issue ?

[DarkCaporaL]

This is what a twin/multi plate clutch sounds like. Previously posted by Skym somewhere on here.

http://www.youtube.com/watch?v=JuRmNDgezuk

[frankiman]

its a single plate clutch

weirdly, i just got a proper alignment done at a Nissan dealership, and i can ear the grinding less than before for some reason