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Old 05-06-11, 09:52 AM   #1
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Location: Mountain Brook. AL
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Stuck allen setscrew in Co-Motion eccentric

Cautionary tale: Our Macchiatto has had its eccentric in and out several
times and adjusted since 8/07 but not for the last year. Recently we tried
to loosen to adjust the timing chain and the R side allen screws (8M diameter,
4M allen) would not budge. L side easy in and out. Removed the BB to
improve access and allow socket wrench allen to be used-it broke. Had
previously twisted through 5-15D the long handled allens I had, so ordered
a Proto 3/8" metric socket set and for good measure two 5/32 Proto impact
sockets as 4M and 5/32 allens are only 0.001" different in size. The impact
socket twisted and bent a little but did free the allen set screws. No
corrosion or loctite involved, but no lube either. All threads in good condition.
Thoroughly slobbered grease over all moving parts and reassembled with
all hunky dory. Lesson: lube those set screws!! Eccentric is heavily anodized
aluminum, set screws steel, plated and high quality as the sockets did not
deform under the torque required which twisted three allens and broke a 4th.
Pix attached.
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File Type: jpg allen wrench twist 003.jpg (98.5 KB, 30 views)
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Old 05-08-11, 06:15 PM   #2
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When bolts have high torque values and there is a possibility of moisture or sweat getting in the joint, I will use anti-seize lubricants. Never had a problem, but I generally re-torque all bolts after 2-3 rides. You might want to replace the screws, just for peace of mind.
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Old 05-08-11, 09:16 PM   #3
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Bikes: 2006 Co-Motion Roadster (Flat Bars, Discs, Carbon Fork), Some 1/2 bikes and a couple of KTM's
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You are not alone, not us, but another Florida team had a similar issue on their Speedster.

Expecting similar possibilities on our Roadster, I somehow lucked out on an ebay buy of a new Bushnell eccentric for short money. Couple of weeks back while accomplishing some routine maintenance, I was able to have the time to make the swap. Out of curiousity, I took our oem eccentric and 4 set screws, and compared that to the new eccentric and 4 aluminum bolts to plug the holes. New installation was around 70g lighter if I remeber correct.

BTW, I am assuming your Macchiatto has 4 set screws threaded into the frames BB shell.

Glad it worked for you.

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