I'm an idiot - Is this fixable?

The problem is this Nick the bolt sheared because it has bottomed out and as locked up hard on the bottom , after 50 years in engineering the only way you will sort this is to drill out the old bolt and re-tap the thread , we may have to use the other part in the photo the bit that the bolt passes through as a guide to keep it on centre , or I may have to make you a guide we will see when I come up , but I can't see an easy way out other than if you are lucky with an Ezi out sometimes works. Dad

Hi Sid- I do not think the bolt bottomed out? If it snapped whilst Nick was fastening that stub shaft/flag assembly on- then by design the bolt would not have been at the bottom of the tapped hole in the crankshaft. It needs to clamp the thing it is fixing before it bottoms out.

Or I have mis-understood how it snapped of course...

For years I didn't own or even borrow a torque wrench and relied on a sense of "feel" to judge whether a nut or bolt was tight enough, be it nipped or tight so it wouldn't loosen in use. This has served me well BUT on eventually getting a torque wrench for wheel nuts on ally car wheels I found quite a difference between what I felt was right and what the torque wrench told me - I was doing up wheel nuts far tighter than specified, to my surprise. Not sure it would have been enough to damage a wheel and it certainly wouldn't have fallen off!

However I also found that I did not tighten bike parts as tightly by feel compared with when using a torque wrench in many cases, particularly using small diameter threads like on side engine cases. I also learnt that threads that are oiled or greased should be tightened to a torque 15 to 20% less than specified because the lubricant reduces the apparent tightening resistance/torque and specs are given usually for dry threads. As a result I use "feel" for most things still apart from big stuff and very specific items when I may use the T W. Most British bikes didn't have quoted bolt torque figures anyway! The real risk I find is setting the torque then just tightening 'till it clicks without pausing to feel what is going on, critical as the T W is usually bigger than the socket T bar or spanner I would otherwise use.

I don't suppose any of this helps right now but I just felt like setting out my thoughts on the things, torque wrenches, that is. Good luck with the extraction.

I would wrap some turns of insulating tape round a 4mm or so drill to keep it centered and try an easy out. As others have said it may not even be tight enough to warrant this much effort...

Let me read all this when sober......just got back from a heavy night out in Stratford.

If anyone can spell it out in three (even four) bullet points for tomorrow I would be eternally grateful.

Well done. I think you have learned something if it ever happens again as well.....

First thing I did was get a scriber in there and then a jeweller screwdriver to see if the broken thread would move.......but it was having none of it - seemed seized.........solid. Then I got the drill out and it all came good.