This bolt has sheared on the rear triangle of my Cannondale Jekyll. How on earth do I fix it? What tools do I need? What do I need to NOT do at risk of wrecking the frame?
That's a horrible one.
I think I'd be taking it to someone who knows what they are doing. making a mess of it yourself might make it harder for them.
If you are having a go yourself: Is it held with Loctite? (was the other side). If so, heat applied to the aluminium will break the bond. Heat will help anyway if applied correctly at the right moment (ie., the aluminium will expand quicker than the steel bolt). I would remove the rear triangle and get it on the bench (easier to access and work on then). I'd apply some gentle force through long-nosed locking pliers (fancy molegrips) to feel if it moves. Heat and try again if not. If still no movement... take to an engineering shop!
Not easy to do but you need a sharp fine metal drill and an ez out / screw extractor, with a tap wrench. Order up the tools assuming you don't have them, spending the time waiting soaking the thread with penetrating fluid.
Apart from any threadlock (as above, softened with a heat gun) that threaded remainder probably isn't very tight and might just unscrew with needle nose pliers.
The slightly bigger problem is that the clamp hole it has to come out through looks like it is now misaligned. Did the bolt break riding and then the pivot bore / clamp has opened up?
It really needs to be off and on a bench so both things can be addressed together.
Don't wish to be the bearer of bad news, but it looks like that area has been over stressed and the sheared bolt is the least of your worries.
The eye element that clamps around the bearing using the bolt has opened out and ovalised, it should still be circular only a touch bigger than the bearing it is clamping.
Looking to the left of the photo at the weld between the stay and the pivot end the paint looks suspiciously crazed like there is a failure in the weld below.
Think you're either looking for a replacement stay component or it's time to retire that frame. Sorry.
I am going to say something that may come across as being a bit of a dick.
But looking at the state of the hex socket on the pivot... You pay someone to do this for you.
Looking to the left of the photo at the weld between the stay and the pivot end the paint looks suspiciously crazed like there is a failure in the weld below.
This. Have a good look here before you do anything else. The paint is coming off anyway, so remove it and have a look to see if it's still sound underneath.
And as mentioned above, with the now misaligned bearing clamp, it looks like it happened whilst riding. So also check the clamp area as it's quite ovalised/enlarged now. Might just do back up though with a new bolt, but it's far larger than the original opening so needs a check.
The crazed weld/paint is some raggedy tape on the frame. All good there.
Yeah wasn't me who did that
The fact that the clamp has opened out suggests it's been ridden with a snapped bolt for some time. As above, consider what impact that's had
That’s new triangle time, the bolt has obviously been broken for enough time to open out and ovalise the clamp
As has been mentioned, the fact the eye has opened up as far as it has, could mean it'll crack when clamped back in.
However, I'd remove the axle, and I think you could probably get a small pair of long nosed molegrips in the gap as a first attempt at removal.
Failing that, I'd be drilling and tapping.
+1 for That Looks ****ed and another +1 for "take it to a bolt whisperer". If it's savable, it's likely to be difficult and often every failed attempt makes it worse and takes away options.
That said, if it were me. And bear in mind the sheared bolt might not actually be very tight/stuck- sometimes it's the force of the bolt itself that sticks it, and when it shears it relaxes. Other times the bolt breaks for some unconnected reasons and you have a broken but not stuck bolt. But, I'd still approach it as if it were stuck- or I might have a very gentle test with some narrow locking pliars, but I'd be avoiding damaging the bolt at all. Just to see if it's actually stuck, not to move a stuck bolt.
Axle out first. I assume the head of the bolt is completely missing but if not, remove that. Clean up area. Penetrating oil, leave to soak. Repeat. Clean it up again. Penetrating oil again. Patience is totally worth it.If you have a dremel then getting a little wire brush on it and cleaning up the thread right down to the base and surrounds can pay off- sometimes you'll basically have a seal against penetrating oil with dirt and corrosion, and sometimes you can get rid of that.
Then, I'd get a thin punch onto the broken end of the bolt, and hammer it straight down its length (ie, down the bolt hole essentially). It'll probably be hard to get a really good connection, so doing it a bunch might be easier but it does have to be solid hits. The impact will hopefully loosen it up a little (this is a combination of breaking loose corrosion and dirt, and also literally hammering the thread a little bit baggy, so we're going hard here. DOn't worry about hurting the bolt or thread, it's not going to happen with a small hammer and the awkwardness, but do worry about hurting the surrounds) . Then even more penetrating oil. I'd be very tempted to do a couple of side hits too, not as hard though- this is brutal but it's very effective at breaking corrosion, and also very effective at loosening the actual metal. But it's more damaging, because it's so unequal, approach with great care.
Then, I would be using my skinny locking grips, and applying them as tight as humanly possible. Like, ridiculously tight. I doubt there's space for 2 sets but if there is, 2 skinny sets is way better than one fat set. Then very gentle rocking back and forth. And then retighten, because the rocking will squish the threads. Probably repeat. And then finally have a go at actually backing it off, feeling and listening at all times for any movement, or any movement of the tool on the bolt.
If that's not working- and I wouldn't push it far- then I'd escalate a little bit, and grind a flat onto the bolt, with my little grinder or a dremel. It ought to be possible to do 2 opposing "sides". This is a twofold thing, it gives you a better grip with the grips, and also it puts very localised heat into it. Not really as much as you'd like, with little bolts, but it can help.
Then I'd try again. And again don't push too hard, if it feels like the tool's slipping stop and retighten. Often you'll have to retighten a couple of times as it beds in and squishes the surface a little, this is good as it improves the potential grip but if you don't retighten it creates looseness
If all that doesn't work, I'd be wondering about hitting it with fire, at the expense of the paint etc. Actually, tbh I'd probably have done this earlier but I don't want to recommend that, cos it's not my paint. But the whole deal looks ugly enough that I'd probably go direct to fire.
In the end, if all else fails drilling out is a pain in the cock and can go wrong easily, but it's probably quite doable here. I hate drilling out bolts with a passion, I am too careless.
Good work. Now give it a clean you monster!
James certainly is good and a top bloke too.