We recently rebuilt the final drive for a Hitachi 200-5 excavator and there is a grinding noise. The oil level is okay. Any suggestions or things to troubleshoot?
I would start with draining the oil. If you see lots of metal I would pull it apart again. I've rebuilt a fair few ZX-3 final drives and the only things that come to mind are the shims for the planet pinions. IIRC there should be one on each side of every planet pinion. Then there's the roll pins that hold the planet pinion shafts in place. If one was forgotten or if on backed out, the shaft could walk back and forth and grind into the carriers. There is also a thrust bearing or bushing in the center of the cover to prevent the sun gear from grinding into the cover.