Thread: Swift folders
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Old 05-27-06, 10:20 PM
All ur bike r belong Enki
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Join Date: Aug 2005
Location: San Fransicko
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Bottom bracket R & R

Damn...what a pain removing the bottom bracket on my Swift was! The 350 ft/lb impact gun struggled before almost totally ripping apart the teeth on the lockring, but it still wouldn't budge! So I went at it on the drive-side of the bottom bracket, which came right out without complaint. Once I removed the bottom bracket assembly, I hit the lockring again several times with the imapct gun, and slowly, but painfully, the lockring started to turn, emmiting this really weird ear-splitting low-pitched squeek, which sounded like a cork bing twisted from a bottle, only much more metallic. The imapct gun chugged and hammered-away, while the lockring slowly submitted , turn by turn. Finally it popped out, to my relief, as the tool kept chewing-off bits of the lockring teeth. Whew!

Ok, so what was up with the bottom bracket. Have a look at the pics. 2 things: rust, and dry threads. No anti-sieze compound...not even a trace of grease on the threads. Umm, did someone at the Xootr plant forget to properly prep the bottom bracket threads before installing? I did notice that the lockring was tighter than hell, and wouldn't go-on by hand, while the fixed flange was totally the opposite. Was the lockring intentionally oversized, then the bottom bracket shell heated before installing to give a pressed fit? Whatever it was, it sure didn't seem like it was intended to be removed.

My friend at Xootr quoted the bottom bracket size as 68x107, but warned me to measure it for myself, as the assemblers can and do change specs on bottom brackets to get a proper chainline. The actual size of the bb on my bike is 68x116. So back to Nashbar the UN-53 bottom bracket goes, and in it's place a shiny, new UN-73 68x115 from my local Performance bike shop (Shimano doesn't make a 116mm spindle). The difference betwen the UN-53 and the UN-73 is that the 73 has a hollow spindle (less weight) and a (get this) plastic lockring (less weight, but more importantly, to perhaps prevent corrosion, rust, and siezing in the bb shell).

The stock bb feels like a stone compared to the UN-73. Quality Shimano stuff...the top-of-the-line model as fas as square-tapered bb's go (and I do mean "go", as they seem to be left-over technology replaced by the Octalink and Isis systems).

To insure a less nightmarish removal in the future, I prepped the fixed flange threads with anti-sieze ($3.79 at Kragen), and water-proof grease on the plastic lockring (anti-sieze might melt it, as it contains petroleum distillates and other nasty stuff).

The new bb spins like the bearings are packed in butter...smoooooth. Oh yeah, now that's more like it.
Attached Images
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bb_2.JPG (69.9 KB, 136 views)

Last edited by james_swift; 05-28-06 at 07:20 AM.
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