I've read all the threads I could find regarding fixing the grinding in neutral when clucth pedal is not depressed. I already tried replacing the throwout bearing - which was bad. But it didn't fix my issue. One person said the input bearing can be accessed by taking off the bell housing. Other people are saying the entire transmission has to be disassembled to replace this troublesome bearing.

What is confusing is that the Mazda manuals don't refer to anything as an "input shaft bearing". Here are the two bearings that I believe interface with the main drive shaft (input shaft).

R501-17-295 Bearing, Ball-Main Drive Gear
R502-17-283 Bearing, Needle

It looks like the first one can be reached after removing the bell housing. The other one is a little more involved. Does anyone know which of these bearings is likely causing the rattling in neutral except when I depress the clutch pedal?

 

Most likely the R501-17-295
Mine does it and that's the one I need. Removal of the bell housing should be enough to get to it.

 

Thanks CnantGoStraight. I also bought the SST that goes inside the crank case while you pull the bearing off. Not sure what it does. But it wasn't that much $.

 

When you're done I'd like to buy that SST. I think it's just there to keep 4th synchro from falling out of place.

The input shaft bearing is the ball bearing. You can definitely replace it by removing only the bellhousing, however you'll need a narrow jawed puller with very deep (10" or so) reach. The FSM removes it toward the end because the mainshaft can't come out with it until the rest of the gearbox is cleared out.