Sheared bottom bracket
bike-a-swan
Posts: 1,235
Right, I have a problem that I suspect is going to appeal to the power tool enthusiasts of the forum.
My hybrid has (or had) an old style user adjustable square taper BB, the sort with a bit (cup?) that screws in on the driveside with one set of bearings, then the axle goes in from the other followed by the second bit with bearings and then a lock ring. one of these, in fact:
http://www.diaryofamountainbiker.co.uk/dec08/21-12-2008_07.jpg
Anyway, while just riding along (really, for once), I heard a pretty nasty crack, felt the cranks come loose and stopped in time to see ball bearings making a bid for freedom. I got home, and the driveside cup has sheared around the circumference of the cup, with the result that I now have 1 cm or so of bb thread still threaded into my frame. Obviously there is nothing to grip on with a spanner to get it out, so I'm looking for suggestions on how to remove it without destroying the frame. I've had a punt at it with the only saw I have that'll fit in there (I've used it to cut steerer tubes before now, so it should do) and a file with little effect as they can't get any purchase on the thing to start cutting.
Any ideas?
Cheers in advance
My hybrid has (or had) an old style user adjustable square taper BB, the sort with a bit (cup?) that screws in on the driveside with one set of bearings, then the axle goes in from the other followed by the second bit with bearings and then a lock ring. one of these, in fact:
http://www.diaryofamountainbiker.co.uk/dec08/21-12-2008_07.jpg
Anyway, while just riding along (really, for once), I heard a pretty nasty crack, felt the cranks come loose and stopped in time to see ball bearings making a bid for freedom. I got home, and the driveside cup has sheared around the circumference of the cup, with the result that I now have 1 cm or so of bb thread still threaded into my frame. Obviously there is nothing to grip on with a spanner to get it out, so I'm looking for suggestions on how to remove it without destroying the frame. I've had a punt at it with the only saw I have that'll fit in there (I've used it to cut steerer tubes before now, so it should do) and a file with little effect as they can't get any purchase on the thing to start cutting.
Any ideas?
Cheers in advance
Rock Lobster 853, Trek 1200 and a very old, tired and loved Apollo Javelin.
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Comments
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well as that is also the bearing race it will be hardened so cutting will be not very effective.
but a die grinder will do it OK.
you will need to "cut" a step/hole in the shell so you can knock it around to unscrew it.
i would be tempted too, if you dont have the tools, take it to someone to do.
an other possibility is to weld some metal to the cup and use that to turn the cup.
but you need the tools."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
there we go, power tools!
cheers!Rock Lobster 853, Trek 1200 and a very old, tired and loved Apollo Javelin.0 -
right, in case anyone else gets this problem, I had a shot at doing it with non-power tools (they don't make texco value welding kits!) and managed it with a hacksaw, screwdriver, hammer and patience. I used an old and already partially knackered hacksaw blade to work into a small crease in the metal from where it sheared, and opened it enough to wedge an (old) screwdriver in. I then used a hammer to 'chisel' the bb round in the shell until it cam out far enough to reach. sorted!Rock Lobster 853, Trek 1200 and a very old, tired and loved Apollo Javelin.0
