have a late FS5W71B that is really noisy in neutral at idle

- loud gnashing and growling noises - noises go away when clutch is depressed, but can also be heard when coasting in 1st-2nd with clutch out; there were no shifting problems; T.O. brg is perfect

I have studied the manual section from the database - concluded it was an internal problem, and begun dis-assembly

i have removed both housing sections and have the center plate mounted on vise with a home-made adapter

all the "end" bearings that mount in the housings are butter smooth and not noisy, gears all perfect, baulk rings look fine

- nothing obvious as a potential source of all the noise

- can't tell about the center bearings yet, and i have to check all the clearances before i start taking it all apart

but before i do that, does anyone have some ideas based on your experience as to what i should be looking for and expecting to find???

curiously, i had this box installed a few yrs ago & it was not noisy when i pulled it out back then - it's been in dry storage ever since, standing on its nose

all advice & tips appreciated, including links to other threads on this, as well as best parts sources

TIA

Are you sure it's the box and not an engine bearing? Depressing the clutch side loads your thrust bearing in your engine and might be why the noise goes away.

I'd look at the input shaft bearing on the transmission. In my experience, that's what it's been.

Mine had the same symptoms. It was my countershaft bearing - right below the reverse idler. My reverse idler gear was torn up a bit, metal into the countershaft bearing, countershaft bearing = toast... The previous user(s) of this transmission had apparently been grinding into reverse. Get the rebuild kit, replace all the bearings.

I am overly cautious about shifting into reverse now.

have it completely apart - none of the bearings exhibit any roughness to account for the noise

- i bought the BK104 kit from O'Reilly's and got it today - it is a comprehensive kit, with all the correct brgs (56mm yes), seals & gaskt (japan made, thank goodness)

the new brgs might be a bit "smoother" than the old ones (tested clean & dry), but it's a tossup imho - i am still puzzled

cuz, in neutral, where i heard the growling, the only things turning are the C'shaft & the input shaft

took awhile to ID the trans - it's about a mid-'80 - some parts correspond to the earlier ID specs listed on other threads/sites and some correspond to later trans ID - mid-year changeover issues

- i pulled it out of a ZX at pick-n-pull about 6 yrs ago but never wrote down the year or other ID info at the time - - the trans does have a number 7210886 stamped on the top of the bell, but nowhere does anyone mention that as an ID issue, and it has a white 19 tooth speedo gear & brass 5th

i'll now order the nuts & rest of the minor pieces from nissanpartszone