After seemingly completing a final drive spline inspection, lubrication, and reassembly,  I moved a rag and found a small rubber donut.  I can't seem to find any pictures or diagrams that clarify where that donut belongs.  Any help would be much appreciated.






  Thanks

Some aftermarket shock absorbers—Progressive, for one—have o-rings similar to that one that fit within the lower mounts and tend to fall out when the shocks are dismounted. 

Consider putting your bike's model and year in your profile so it will show up with each post you make.

It isn't a part of the final drive that can come out when the drive is removed for lubricating.

Thanks for the responses.  I am relieved to hear that the mystery donut does not appear to belong in the actual drive shaft/final drive assembly.  I would like to return it to it's proper placement and would appreciate any clarification as to where, exactly, it belongs.  At this point, I am thinking that it may belong on the inside of the lower shock mount.  The bushing at the bottom of the shock appears to cracked (not through).  I would like to replace it, if I can locate the proper part.  Should I expect to find a manufacturer's name/description on the shock?

The easiest way to identify it maybe to post a picture of it.

If any Forum member can identify the rear shock on my K100, please contact me.  I would like to find replacement rubber bushing for the shock.

Larry Myers wrote:If any Forum member can identify the rear shock on my K100, please contact me.  I would like to find replacement rubber bushing for the shock.

It looks like an old Fox Clicker. Are you certain it had o-rings (rubber bushings) to begin with? The canister attached to the hose at the top of the shock has no identification on it?

+1 on the Fox twin clicker identification.  The blue knurled knob on the bottom is the rebound damping adjustment.  The red knob on the reservoir is the compression damping adjustment.

If the shock mounts are anything like the OEM Ikons fitted to my Cali 1100ie then the O-rings fit in a groove either side of the main metal bush mount. They're there to try and prevent water ingress into the bush and so to stop the bush corroding to the mounting spigot on the bike. Take the nut off the bottom shock mount and check for a groove or an O-ring. If they're there, refit the O-ring with some water-resistant grease (OEM is quite frequently a white marine-grade grease).

Wilbers have the same arrangement on their bottom shock mount. Two O rings keep dirt out of the grease that lubricates the sleeve inside the mounting eye.
Inspect the bottom mount, if an O ring is missing replace it ASAP.

Good luck.

Thanks for the good suggestions.  The O-ring that was still hanging around after my spline lube was, in fact, intended to keep dirt and moisture out of the lower shock mount.  It was from the back side of the bottom of the shock.  Thanks to your advice, it is back where it belongs.

Larry