Here are internal pictures and closer views of where your aluminum shavings might be coming from.

Extra images

[2015 Z Force 800 53/Trail EPS]

That's the worst design I've ever seen. So there is no shoulder for that inner pinion bearing and if that yoke retainer bolt is loose...or breaks the pinion can be pulled-in? Wow...and I see where the aluminum is coming from. Bet my bolt is loose...like so many other CFM bolts are. Think I would find the best bolt made for that and give it some extra torque...with thread-loc.

That's the worst design I've ever seen. So there is no shoulder for that inner pinion bearing and if that yoke retainer bolt is loose...or breaks the pinion can be pulled-in? Wow...and I see where the aluminum is coming from. Bet my bolt is loose...like so many other CFM bolts are. Think I would find the best bolt made for that and give it some extra torque...with thread-loc.

It had a 10.9 10mm fine thread which is what I replaced it with. I could not find a 12.9 hex head at the hardware store. They were Allen heads.

[2015 Z Force 800 53/Trail EPS]

All I know is I have a bunch of play in that area and it sounds...and feels like the pinion is moving in and out about 4mms or so while on and off power...so I guess I better put this on my schedule pretty soon.

When you tore yours down, what did you find?

[2015 Z Force 800 53/Trail EPS]

When you tore yours down, what did you find?

I haven't done mine yet. Maybe this winter.