tight bottom bracket airborne thunderbolt

ascurrell
ascurrell Posts: 1,739
edited September 2008 in Workshop
Any help appreciated,
basically i have an airborne thunderbolt bought 18 months ago and haven't really used, another guy built it and i think the bb and frameset were new.
have now decided to remove campag chorus bottom bracket, it was extremely tight to remove.
iI believe the thread to be english. [please tell me if it may not be]
Have bought a veloce bb to convert and use in conjunction with a compact chainset.
The problem is it's so tight to fit, in fact i daren't.
To make things worse the chorus bb i took out is just the same [it was very, very tight to remove].
Not sure what to do, i'm wondering if the original bb was fitted correctly [what could go wrong?]
I'm a fitter by trade so i've drilled / tapped many holes in my time but just not sure what to do for best as i fear i could damage the bb thread.
A ny advice welcome / needed
Apologies for long winded description,
cheers, Scurry

Comments

  • Meds1962
    Meds1962 Posts: 391
    I did the same a few weeks ago on my thunderbolt but it was a dura ace bb in place of a 105. I didn't have any touble with removing the old or fitting the new and my frame is about 3½ years old - are your threads gunged up with something??
    O na bawn i fel LA
  • bill57
    bill57 Posts: 454
    Take it to a good bike shop, and get them to chase the threads with the proper tool. It should be a "firm" fit, ie needs light leverage to fit, but not so you fear you're going to split the BB shell - which it sounds like you're worried about.
    You have greased it haven't you? Course you have, you're a fitter.
  • ascurrell
    ascurrell Posts: 1,739
    thanks for input guys, i think the bottom bracket will need to be chased.
    grease woldn't make much difference although i did spray with some wd40 to try and clean threads. It was so tight to remove the one fitted, i had to use the bottom bracket tool with 12" adjustable spanner and a lot of force. Even attempting to fit either just feels so tight,
    do you know if they are chased by hand or is a tap used?
    thanks, scurry
  • bill57
    bill57 Posts: 454
    It's a big tap.
  • ascurrell
    ascurrell Posts: 1,739
    Yeh Bill,
    just checked, Park tools make them and St Johns Street cycles sell them, pretty awkward to start central i imagine.
  • bill57
    bill57 Posts: 454
    I know what you mean, when possible I always used to tap using the head and tailstock on a lathe to get it central. But (I'm prepared to be wrong here) though I've never used a BB tap, I think they're designed to be used both sides at the same time, so each one centralises the other - if you see what I mean.

    http://images.google.co.uk/imgres?imgur ... f%26sa%3DN
  • RogerTheDodger
    RogerTheDodger Posts: 16
    The BB threads must be chased. End of story.

    If you bought the frame from a shop and its reasonably local to you take it back to them and tell them to do what they should have done before handing the frame over to you i.e. chase the BB.

    If it’s not local then take it, to ideally a frame builder or if that s not possible to a shop and get tem to chase it. Get a receipt from whoever does it and send it to whoever you bought the frame from.

    It should never have been sold to you in the condition you describe.

    Roger

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