mickle
innit
- Location
- 53.933606, -1.076131
Right hand cup has a left hand thread....
Help! My bottom bracket is totally seized
- Thread starter Jimmy Doug
- Start date
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OP
OP
Jimmy Doug
If you know what's good for you ...
I know it's reverse threaded - it's an English bike.
mickle
innit
- Location
- 53.933606, -1.076131
If you've buggrered the splines you're at the hacksaw stage of the job. Make two or three cuts through the cup towards the bb shell. Cut as close as you dare to the shell - and then start in with a small cold chisel tapping the pieces away from the bb thread.
Good luck, it's a horrid job.
Good luck, it's a horrid job.
robgul
Legendary Member
You might be able to grip the flange on the BB in a big engineer's vice (horizontally) and the use the frame as a lever ... gently rocking to get it started ... not forgetting the reverse thread on the chainwheel side of the shell. Filing a short flat on one side of the flange will help the vice grip .. and it's a 3 handed/2 person task to load the frame on the vice jaws.
OR get a deep tray (a foil baking tray works) and sit the BB shell in it with diesel/heating oil and leave it for a few days [This is a job for the garage or shed !] - it's quite penetrating. You can also try the same process but with Coca Cola, yes really, as that has some tendencies to soften and release corroded parts.
.. for my money the big vice is the most likely route to success
Rob
OR get a deep tray (a foil baking tray works) and sit the BB shell in it with diesel/heating oil and leave it for a few days [This is a job for the garage or shed !] - it's quite penetrating. You can also try the same process but with Coca Cola, yes really, as that has some tendencies to soften and release corroded parts.
.. for my money the big vice is the most likely route to success
Rob
Smurfy
Naturist Smurf
- Location
- Smurfette's Kitchen
A month ago I wrote reams and reams on the engineering workshop practice of collapsing the threads (screw threads that is, not forum threads!) It can be done with a hacksaw blade as Mickle said, or a file as I described.
OP
OP
Jimmy Doug
If you know what's good for you ...
Well, I've just come back from the bicycle shop. Shame I didn't get to read this great advice before leaving - but I'm off tomorrow for a week and I'll need my bicycle for my journey to work when I get back. I hope my lbs knows what he's doing. He said he'll use a heat gun and feels optimistic he can crack it. I'd have preferred Mickle's method as it wouldn't damage the paintwork, but the lbs reckons he can avoid too much damage. I'll let you all know how it goes.
OP
OP
Jimmy Doug
If you know what's good for you ...
This is great advice. I'll remember to look next time! Hopefully there won't be a next time, though! I intend loosening, greasing and re-tightening the bb on a very regular basis after this - should the bike frame pull through!
Smurfy
Naturist Smurf
- Location
- Smurfette's Kitchen
The expansion coefficient of aluminium is around double that of steel. The differential expansion between an aluminium bottom bracket shell and a steel cup makes it easier to remove the cup, and can help break the corrosion 'seal' between the two parts. The same trick can be used to remove a steel pedal spindle from an aluminium crank arm.
It's a dodgy business whatever you do. Collapsing the threads carries the risk of damaging the threads, and using a heat gun isn't great either, aluminium alloys can slowly age harden at room temperature, and the speed with which that occurs increases dramatically at 100-200 degrees C.
A friend of mine used to use a phrase I don't repeat all that often, but I'll make an exception here.
F*ck Me O'Reilly.
I've had one looked like that before, strange thing was although the BB felt a bit grindy it was running much better than might be expected. Those ball cages do tend to collapse, I rebuild them with loose balls.
OP
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Jimmy Doug
If you know what's good for you ...
Looking at the photograph above brings back many memories. I remember tinkering around with bearings like that when I was a kid. I wasn't so worried about breaking things in those days. Nostalgia! I wouldn't go back to the darn things, though!
The issue is mostly that the caged bearings are only produced for the cheap end of the market nowadays, so aren't built with quality in mind at all. I've got some steel frames that are running caged bearings that are 40 years old - 'Made in Britain' quality, and they're hardly even worn.
For the bike you see in the picture, the crank felt awfully rough to turn, and with the cranks off I couldn't even turn the spindle by hand! Ended up replacing it with a sealed unit covered in plenty of copper-slip, so hopefully it should require little maintenance.
OP
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Jimmy Doug
If you know what's good for you ...
How should I grease - assuming my lbs is successful? Is copper-slip the way to go, or is there an incompatability with aluminium?
I suspect the cartridge in my bike wasn't greased in the factory. The bike isn't that old - just about 3 years - and I hope to get at least another 3 years out of it. Hope heating the bb bracket won't weaken the frame too much.
Copper-slip is better to use than grease. It's designed to be an anti-seize compound, rather than grease which is designed to be more of a lubricant. It's also harder to wash out.
When fitting the new bottom bracket, just apply a generous helping of copperslip over the BB's threads, preferably covering the whole of the threads. You can't put too much on, but any over a certain amount will just be waste/excess.
Your frame shouldn't be weakened from the process. I've had to do this for quite a few people on a range of alu and steel frames, never had an issue or failure following the procedure.
OP
OP
Jimmy Doug
If you know what's good for you ...
Is it true that copperslip should never be used between two identical metals? In my case, that would be OK, as the frame is alu and the cartridge steel (I think!). I've read that copperslip applied to two identical metals can cold weld them together.
Never heard that myself, and I haven't had any issues using it with a steel BB in a steel frame.
