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I.ve picked up a lovely old merckx road frame from a mate, but the bb is stuck. i want to run campag so the shimano un73 type bb has to but its stuck. with liberal plus gaz, the bb tool clamped in place with some threaded rod and the tool clamped in a bench vice and with all my weight, i've managed to get it to move half a turn. but now all the splines in the bb have sheared. I've got the non drive side insert out, but can
t think what to do next.
I have acces to a machine shop, and was thinking if i could some how get the spindle out then maybe i could make a tool to come in from the non drive side, but i can.t see if there's a way to get the bearings out.
Any help much apprecieated
alloy cups, drill it (I've done this, 2mm or so, work your way round).
You should be able to get the axle/bearing assembly out by impact if it's the same as UN72 too.
Drill where? And impact on what? The axle, from drive side to non drive side? Are we talking Hydraulic press or mallet?
I bet you've checked about ten times you are turning it the right way:-)
Happy Al is right drill it it will be worth it in the end
With older BBs you could remove the axle then put a big nut and bolt through it. As it is a LH thread you can tighten the bolt onto the flange with a big spanner which should loosen the cup. I've no idea if there is a flange in a modern BB to tighten a nut and bolt onto, though.
whack axle from outside/drive side.
May be better to keep it in as you want to drill around the bearing I guess (like what I did) so you are removing the material right by the thread.
OR remove the axle/bearing, you could just saw into the cup from the inside, split it, then collapse it (you'd prob go into the threads a bit tho)
Despite still not understanding what i.m supposed to drill or in what direction, i'm delighted u both think this will work!
not done this sort of thing before?
So did you drill through the bearing between the balls as it were? Having done that how do the holes help u get the bb out?
Yes, but am having a bit of brain fade. my plus gaz snd clamped bb tool has always worked before...
You may be way past this point having sheared the BB spines, but last time I had a stuck BB, truly truly stuck, not a millimeter of movement I did the following.
3 days complete submersion in coke, I don't think it matters if its regular or diet.
Then I submerged it in ice cold water for about 10 mins, then poured boiling water on it. And it then came off with minimal effort.
The freeze thaw causing a tiny amount of shrinking/expansion of the metal moves it enough to break the rust seals.
We used to get a local fabricator to weld a length of scaffold pole onto the bb and then walk it round til it was out.
I mean drill the BB cup out as close to th threads as you can then collapse it. Work your way round with a small drill bit, this will of course be outside the bearing.
Or hacksaw a slot (or 2) in the cup and collapse it.
al, its a square taper BB not one with cups n stuff.
you have to drill through the bearings so the axle comes out before doign the saw thing that al's suggesting.
We used to get a local fabricator to weld a length of scaffold pole onto the bb and then walk it round til it was out.
This.
Although I used a slightly smaller metal bar
Its not an italian thread is it?
If it's alloy cups, then a 32mm hole saw is the trick - it'll cut through the alloy cup leaving the threads behind. Then wallop it out and clean out the threads with a tap.
If it's steel cups, then weld the axle to the cup, clamp the axle in a vice, and rotate.
I've never failed in shifting a BB yet 🙂
Is it out yet?
I hate not knowing the outcome on this sort of thread.