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2011年3月11日 (金)

Teikoku Frame Restoration (Cottered Bottom Bracket Disassembly)

次回、この記事の日本語版を投稿します。

So far we have seen the Teikoku Bicycle before assembly, and, in the last installment we saw how to remove the fork and clean up the chrome parts.  This week we will look at how to disassemble a cottered bottom bracket.

At first glance one may be tempted to start disassembling the bottom bracket by trying to remove the cotter pins; however, as we will see later, the cotter pins are removed last!
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Start by removing the locknut using a C-spanner.Img_8304

The adjustable bearing cup is threaded into the bottom bracket and thus can be removed by unscrewing it.  If necessary a C-spanner can be used by leveraging the notches in the adjustable cup, just be careful not to damage the threads. Notice that nuts to the cotter pins have been removed, but the cotter pins themselves remain attached.
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Pull out the adjustable bearing cup, protective sleeve (if there is one) and axle.
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Once the adjustable bearing cup has been removed it is possible, but not necessary, to removed the cotter pin.  This is referred to as a crescent (half moon) cotter pin.  I have heard horror stories of people who have tried to back out the cotter pins prior to removing the adjustable bearing cup, only to permanently damage the threads on the bearing cup.

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Though the cup on the other side can be removed using a pin spanner, it is not necessary as the bearings and cup can be cleaned from one side.  There are eleven 1/4 inch ball bearings for each bearing cup.

POINTER: When it comes to ball bearing replacement the rule is all or nothing. Replace them all, or don't replace any. Never just replace one ball bearing, that is a sure way to destroy the bearing cup or race.  Replace with new ones or don't replace them at all.

The yellow sleeve protects the grease from foreign matter that may fall down from the seat tube.
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Notice the races on the axle.  Zero wear.  Proof that this frame had never been used.
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As mentioned before, to keep parts organized, after cleaning each part place it in a small bag and label the bag. All the small parts belonging to an assembly, in this case bottom bracket assembly, are then placed in a larger bag.
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In the next post we will take a look at how to clean up the paint. 

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