Kronos XTR Front Diff Maintenance - what is this part?

[BrettOlbrys]

I'm doing maintenance on all of my diffs and I'm not sure what this part is and why it's there. This is the front diff and they appear to be a washer or spacer of some kind, and there are two of them that were stacked on top of each other, and are not shown in the parts exploded view for the diff. What are they, why are they there, and are they necessary because they seem to not be performing any function?

 

[morrjr71]

Those are shims, and they are used to make the gear mesh between the input pinion and the ring gear better. If you were to remove them, your gear mesh would be off. and you could strip either the ring gear, the input gear, or both. Put them back on the diff the way you found them.

 

[BrettOlbrys]

Those are shims, and they are used to make the gear mesh between the input pinion and the ring gear better. If you were to remove them, your gear mesh would be off. and you could strip either the ring gear, the input gear, or both. Put them back on the diff the way you found them.

They don't seem to do anything because its center hole is very large and it can float on the cup (see image).

 

[morrjr71]

Even though the hole is large, the shim is held in place by a groove in the gearbox case and gearbox cover. Once it's in place correctly, it won't move around.

 

[Horatio]

The shims placed between the bearing and the case moves the differential over. Placed on the bevel gear side, the gear mesh is made tighter - 0.1mm per shim.

Placed on the opposite side, the gear mesh would be made 0.1mm looser per shim.

Correct shimming ensures smooth running gears and helps reduce wear.