Difference between revisions of "Shimming Eccentric Bottom Brackets"
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===Reaming the Shell Round=== | ===Reaming the Shell Round=== | ||
Revision as of 05:57, 1 December 2006
Recently, I put together a 17" 2006 Zion 660EBB Singlespeed frame.
It has an eccentric bottom bracket with dual locking set screws.
Contents
Reaming the Shell Round
For the best possible fit, I will be reaming the bottom bracket shell round. I have reamed many bottoms, and I suggest grease for most.
I will use an adjustable hand reamer (MSC # 02239135) Industrial size M. This will eliminate the distorted shape and make the shell easier to shim.
The reamer is huge. OAL 410mm.
A 12 point socket helps drive the reamer. It may take about 50 rotations, so don't use a rickety setup.
The reamer requires the use of a cutting oil as well. Motor oil is fine in a pinch.
After a light cutting pass, the distortion in the shell is obvious.
Shiming the Eccentric
I will fill the gap using some stainess steel shim stock. It is best to use a single shim so that it is as thick as it can be for durability sake. I prefer stainless shims over brass for the same reason.
A 0.010" shim and a 0.0015" shim. In the end, just the 0.010" shim was used and it was a very snug fit.
The greased shim with a bend to help installation
Hardware Replacement
The two round head cap screws were replaced with Stainless Steel Cap screws for use with a larger wrench and matirial to grab in a worst-case situation. Now a 5mm allen wrench can be used.
Greasing and Installing
Marine Grease. Use marine grease. Its what I use when reaming bottoms.
Test fitting.
I also need to find a way to rust proof the edges.
Park SPA-2 tool is used to roll the cam.
Proudly made in Taiwan.
