so i properly prepped the BB shell (faced BOTH sides and chased
threads) and re-installed my UT crank/BB...and it still creaks a bit.
less now, so the BB shell facing definitely helped. but creak it still
does. i think it's the bearings moving around inside the BB cups.
while snug, the bearings arent tightly fitted to the cups as in other
external bearing BB designs.
so that got me thinking...how tight should bearings fit into something
to avoid creaking?
as i mentioned, for mega-exo cranks the bearings are tightly press-fit
into the cups to the extent that a special tool is required to remove/
install the bearings from/to the cups. and FSAs also feature single-
use rubbery crush-washers which i presume also helps fill gaps and
prevent creaks.
for UT cranks, while the bearings are tightly swaged onto the BB
spindle half-shafts, they slide fairly easily into the BB cups and
only have the wave-washer to keep things from moving around. it's
snug, but a wiggle or light bump w/ the heel of your hand allows the
bearings to seat fully during install. that doesnt seem snug enough to
avoid even minuscule movement that could lead to creaking despite the
wave-washer's pre-load.
if designed properly, how snug should the UT bearings fit into the BB
cups to avoid creaks?
also, what kludges can one do to more tightly lock the bearings into
the BB cups?
- what if i stack a 2nd wave-washer in there to double-up the pre-
load? there might be thickness/fit-issues...so it may not even work.
- maybe a couple drops of blue loctite? however...it would make the
cranks/bearings tough to remove when time came...so maybe not a good
idea.
- what about a super thin coat of plumber's putty inside the BB cups
prior to insertion of the cranks/bearings? if not super-careful it
could gum up the bearings, though...
as an aside...the new mega-exo installation includes some yellow (?)
loctite to apply to the BB spindle splines before installing the left
crank arm and let cure for 24 hours before riding. that seems like a
kludge, if ever there was one.