Struggling to crack open bottom bracket on 1970s Harry Quinn I am restoring. Broke pins in one pin spanner already. Penetrating catalyst not helped so far (but will leave it a while yet). Is there some other technique or a spanner with more than just the two pins perhaps? The threaded parts seem to be a much softer metal than the steel frame. Might they have got chemically bonded to frame? Bike is usable (have done a 10 miles TT) but BB is rather rough and this is last bit that needs sorting.
Assume you don’t want to keep the cup……clamp it in a vice and twist the frame. Just make sure you are going the correct way to unscrew the cup.
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Assuming that you can remove the fixed cup, then I’ve had luck with this cheap little item. It’s an M16 left-hand threaded bolt and nut (pic shows two nuts but only really need one). With the fixed cup, spindle and both sets of bearings out of the way, you can just feed the bolt through the adjustable cup, hold the bolt with a socket/extension and then start tightening the nut to the bolt; snug it up tight (the bolt head corners might come into contact with the bearing race surfaces, but those are much harder than the bolt head, so it will deform not the bearing surfaces) and remove the socket. Then you can keep on tightening the nut and because you’re turning left to tighten the nut, it should start moving (unscrewing) the right-hand threaded cup. You can apply a lot more torque to an M16 nut than through a couple of 3mm pins!
Probably worth having the BB threads chased by a LBS after you get the BB out.
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Neat idea, thanks for suggesting. Unfortunately the fixed cup is seized up too though.
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Thanks, might give that a try.
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Given you have tried, I don’t think the BB will be capable of being removed without it being damaged. I also assume you do not want to damage the paint on the frame, hence applying some heat is not recommended. I expect it to be cup and cone design so the cups are probably steel - not alloy which does often corrode in steel frames. One option would be to drill deeper holes in the existing pin holes to allow a 6 pin tool to possibly get deeper contact, and make sure the tool is then locked in place by using a bolt and washers on the axle.
If that doesn’t work I think the solution may need to be quite extreme involving cutting and grinding what’s left of the BB. I have removed a stuck in alloy cup from a steel frame by carefully using a hack saw to cut notches in to the cup and pry those out in sections to avoid damage to the frame threads. Was then able to install new alloy cups without having to run a thread tap through.
Good luck.
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Mavic and maybe others used to do a BB tool (clamped in a vise) that had six steel pins to avoid damaging tight adjustable cups.
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Not having much success finding a 6-pin spanner and not sure if it will do the job (the pin holes are a little bit gouged). Clamping cup in vice and turning frame hasn’t worked but wrecks the threads (which doesn’t really matter as I shall bin the existing parts anyway). Penetrating oil hasn’t helped as yet. Fear I shall have to go down the hacksaw route. Would you give more detail on the orientation of the notches you cut please.
The photo is one of the replacements, the cup i had to remove was a 90s Hope alloy cup.
I had the advantage of the other side coming out without a problem allowing me to remove the axle.
Imagine cutting the cup like a pie into slices, the hacksaw blade cut along the red lines , i checked regularly when i was getting near the frame and was able to break up the sections when i had cut the cup sufficiently thinly.
Thanks for pic. That’s clear and method makes sense. Unfortunately both sides seized so can’t remove axle 
.
Well, that sucks! I’ve also had luck with a (controlled) heat gun and freeze spray.
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https://www.sjscycles.co.uk/tools/royce-bottom-bracket-axle-fitting-tool-rt0006/?geoc=US is a six pin tool option. A couple of deformed holes just means the other holes deform a bit until the cup comes out. Clamping the tool onto the cup with a bolt before turning the tool means you can apply a lot of torque.
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Thank you! Well spotted. Have ordered and will give it a go.
Hmmmm. I’d be tempted to drill down through the threads into one of the pin holes to make a notch, and then use a punch and hammer to try to start the cup turning.
This sounds like destructive (for the BB cups, not the frame) removal territory.
I doubt you have a chemical bonding issue; the BB shell and the BB cup are both steel. They could be rusted together, but in principle can likely be broken free. Whereas aluminum seatpost or quill stem in steel frame could require drilling out if it has corroded into the frame.
If you have a dremel (brand name for rotating grinding wheel; quite cheap, and the sandpaper grinding things are use-it-til-it-wears-down-and-replace) I’d grind flats for a vice or adjustable wrench into the adjustable cup. Try not to nick the frame’s BB shell, but if you do it’s just a place to put touch-up paint so it doesn’t rust. These pics show me grinding wrench flats into anti-theft locknuts (on a bike that I got above-board, for the record).
Once you have wrench flats, more liquid wrench, and just max out your leverage with a long-handled adjustable wrench, or a bench vice.
Then, if needed, you can use one of those cheap tools (like the one @Gregario posted) to get out the fixed cup. I used Sheldon Brown’s instructions to make one years ago; here’s some updated instructions. Here’s a pic of using my tool in action, on a frozen adjustable cup of an old Bridgestone.
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Good suggestions, thank you. I have got hold of a six pin spanner, which fits, and will give that a try next. Then the Dremmel option if needed.
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I had this problem once and my LBS took the frame to a local welder… who welded on a very long breaker bar and was able to break it loose! I think they might have used a super-long pipe or something similar. May be less messy than a dremel?
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Top idea! I have a friend might be able to do that (is a frame builder too so understands the issue very well).
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I was so surprised it worked too! Don’t even need to worry about welding it off-center or anything either. Hope it helps!!