BGTV8

It is the input gear bearing and the layshaft rotating - all the layshaft gears are out of mesh so they are spinning and rattling around ....

In neutral, clutch out, engine at idle, the engine is driving the input shaft, the gear on the end of the input shaft (inside the box) is spnning the layshaft - the gears are all out of mesh, and they are all having a little rattle around. Worse when the gbox oil is hot, a bit muffled when oil is thick and cold ...

Can be a fearful din if clearnaces open up and gear bushes have worn a bit on lay shaft (not main shaft as it is not spinning in neutral). Can also come from the front main shaft bearing - it "sits" in a recess in the input gear and if that has worn a bit you can get some rattle out of the mainshaft front bearing itself.

Bit hard to decribe in words - but if you can find a schematic of an exploded g/box, you wll get the picture fairly quickly.

When you put your foot on the clutch, drag in the gbox stops the input shaft from rotating and so does the layshaft and all its gears - whine.rattle disappears.

Not likely to be the pilot bearing in the flywheel as it should be rotating at the same speed as the flywheel and input shaft as the clutch is engaged ... so has to be gbox bearing and/or rattle from layshaft.

Only way to prove it is remove and strip the gbox ....

I personally only worry about bearing whine when gearbox has drive going thru it, or shift quality becomes an issue, or syncro's get the crunchies ........

RB