Rear Drive Oil Change Query

[Our Gee]

Apologies if this query is in the wrong section. Just been treating my 2012 Twin Cam to a rear drive oil change and Spline Lube. Everything went smoothly and re-assembled. Then I had a browse at the Max BMW parts fiche and noticed that the parts diagram for the rear drive shows a "Centering Ring", part No. 33 11 7 707 796 located on the Wheel Speed Sensor. It looks like this part is fitted prior to the "O" Ring seal. I don't recall seeing this part whilst removing the Speed Sensor or re-assembly. I have searched my garage floor in case I dropped it to no avail. The parts fiche for the 2005 / 2009 RT does not show this part.
Has anyone else noticed this.
Thanks.

 

[Deleted account 181015003]

On the later bikes you dont fill through the ABS sensor hole there is a plug in the casting just for filling

 

[Our Gee]

Appreciate the reply Steve but as I have filled through the Sensor Hole I really need info on the "Centering Ring".