"Davy" <[email hidden]> wrote in message
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Quoted message said:I am renovating my 1950s Elswick-Hopper Lincoln Imp but am
experiencing a creak from the bottom bracket when the left
pedal is at the 11 o'clock position.
The fixed cup when screwed in does not bed down squarely
on the frame - difference of 0.8mm between opposite sides
(equivalent to about one thread pitch). Is this within
tolerances?
I've seen worse, but it's not ideal. Sounds like one of
three things - dodgy thread on cup; dodgy thread on frame;
bottom bracket shell not faced properly. Much more likely to
be one of the first two, given that it's an old frame. Is
the cup loose in the shell? Try another cup and see if it's
any different. (Make sure it's a decent one...)
Quoted message said:But if I really tighten it down then it does go down flat;
but them presumably the cup is distorted to fit the
bracket, and so also will be
the
Quoted message said:ball bearing surface?
Cup able to move in threads allowing it to fit flush? Sounds
like the dodgy thread idea to me.
Quoted message said:When I rotate the axle by hand it seems to have a slight
wobble in it. Anyone any idea on how I can check if the
axle is straight? Rolling it on glass does not work since
the bearing flanges act as wheels and hold the axle
surface off the glass.
Difficult. I presume it's the left side that's possibly out,
because it's normally pretty easy to use the chainring to
assess this if it's the right. (If it *is* the right, and no
deviation is evident in the ring, or any deviation is
obviously the ring itself, don't worry about the axle.) If
it's possible (which it may not be), fit the r/h crank to
the l/h side to use it to check.
Your problem could well be a dubious thread on the
adjustable cup side. If it's loose (which it must be
slightly, to take up the 0.8mm), it's probably moving
slightly in the frame. See what changing the cup does; if
other cups are the same, you have a bigger problem. Might be
possible for a framebuilder to sort it out - usually needs a
bit of braze in the thread followed by a retap. Or you could
have it reamed and converted to Italian thread, if the
shell's thick enough (and you can get 36x24 cups to match
your axle or chainset, which might not be at all easy).
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