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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: mjydrafter on June 17, 2012, 11:19:45 AM

Title: final drive post mortem
Post by: mjydrafter on June 17, 2012, 11:19:45 AM
I thought you folks might be interested in the postmortem I did on my failed final drive.  When I got the bike it was making a grumbling sound when you would let off the throttle...  So when I did the various spline lubing, I found that the pinion nut was loose...  A bunch of shiny stuff as well as some larger pieces came out in the fluid, and cleaning it up and out with a magnet bought me a little time.  But the noises returned, and it started sounding like a bad wheel bearing, click-click-click.

So when I got back from my early fathers day ride this morning I decided to tear into it and see just what was up.  Here is what I found:

(http://i216.photobucket.com/albums/cc295/mjydrafter/IMG_6594.jpg)
Ring gear and bearings don't look too bad.

(http://i216.photobucket.com/albums/cc295/mjydrafter/IMG_6592.jpg)
Houston, we may have found our problem. :eek2:

(http://i216.photobucket.com/albums/cc295/mjydrafter/IMG_6591.jpg)
Yikes. Boo! :yow

(http://i216.photobucket.com/albums/cc295/mjydrafter/IMG_6590.jpg)
That is one ugly gear, and affirmed that the pieces I was getting out of it were in fact gear teeth.  Poor old girl, something knocked out her teeth.  I assume it was the loose nut, and a bit of old fashioned final drive neglect.

Change that fluid, heck it's only .25l...  I'm using Redline Heavy Shockproof gear lube per a Motobrick member's recommendation.  Seems to be working well, I've put on a few hundred miles so far since the change to my new/used final drive.  So far so good. :yes