Stubborn bottom bracket

I recently converted a nice late-70s Colnago frame and I'm using what I believe to be the frame's original Campag BB. My chainline isn't quite as straight as I'd like it to be and I figured I could fix this by swapping the bottom bracket out for something slightly narrower.

Unfortunately, the Campag BB seems to be fused to the frame. It's probably been there for the last 30 years, collecting moisture that's made its way down the seat tube. I've tried everything I can think of, soaked it in WD40 and the like, tried to "shock" it off with a hammer. It simply won't shift and I'm concerned that when it does, it'll take the thread on the frame with it!

I've read that it's possible to remove a very stubborn BB by heating it with a blow torch, although of course you will destroy the BB and probably the paint around the casing in the process.

Does anyone have any other ideas that won't end up with me having to re-spray my frame?

Cheers,
Rob

First, the BB is probably Italian threaded, so one cup will be threaded the wrong (right) way.. have you taken this into account?

I've never tried heat, think it will depend on the material the BB is made of, but sounds like it's worth a shot.

Chemicals: Try soaking in some tough penetrating oil (plusgas etc.) rather than WD-40.

Mechanical: After soaking as above, tap the BB shell with a hammer etc. Fairly lightly, the goal is to work the penetrant further into the threads, and break the corrosion seal through vibration (not brute-force)

Leverage: Clamp the removal tool on somehow, so it won't slip and ruin your chances. Then either use a big bit o' scaff-pole as a 'cheater bar', or clamp the tool in a vice and user the frame as a lever.

Don't give up! I've never seen a BB that can't be shifted, and only lost one thread (because someone turned the cup the wrong way).

First, the BB is probably Italian threaded, so one cup will be threaded the wrong (right) way.. have you taken this into account?

Chemicals: Try soaking in some tough penetrating oil (plusgas etc.) rather than WD-40.

Mechanical: After soaking as above, tap the BB shell with a hammer etc. Fairly lightly, the goal is to work the penetrant further into the threads, and break the corrosion seal through vibration (not brute-force)

Leverage: Clamp the removal tool on somehow, so it won't slip and ruin your chances. Then either use a big bit o' scaff-pole as a 'cheater bar', or clamp the tool in a vice and user the frame as a lever.

All good advice. Don't try heat, it does nothing but destruction.

Clamping the BB tool on is the best way. As long as you can get one cup off then you can use a bolt and two large washers with nuts all secured through the BB shell and stubborn cup.

And if it's Italian BB then it's the fixed cup which goes the wrong (right) way, lefty loosey

If it's the fixed cup that's stuck, then there's always the old Sheldon Brown trick:

http://www.sheldonbrown.com/tooltips/bbcups.html

no heat. try the plus gas then put it in a vice and use the levarage ofthe frame to undo it

I'm definitely turning in the correct direction. I've got an identical cup which I checked the thread against. I think i'll go with the plus gas and vice trick, seems like the best way to preserve my Colnago's rather delicate paintwork. Don't know why I didn't think of it before! I'll let you know how it goes. Cheers!

Is it the fixed cup that's stuck? What tool have you been using to try and remove it?

I couldn't shift mine with Sheldon's vice technique (I did chip my paintwork, though.) I'd recommend the Campag fixed cup tool and a second, sturdy pair of hands to hold the bike. Stuck parts always seem to surrender in the presence of two people. I think it's easier to commit to maximum effort when there no danger of the frame moving.

I'm definitely turning in the correct direction. I've got an identical cup which I checked the thread against.

Achtung! Unless the cup has wording on it (eg. 36x24tpi or the like) then you can't tell from looks whether it's the same threading as the one in the bike. Frames from different countries have different BB threads. Check Sheldon.

They're both 36mm x 24 TPI which, according to Sheldon, means they're Italian!

An alternative to heating it is to freeze it - you can buy plumbers pipe freeze in decent DIY or hardware shops. Spray that on the bottom bracket and hopefully it'll contract enough to free it. I've not tried this myself but a friend of mine who is a mechanic in a bike shop swears by it (and used it to free a stuck bb I had).