Snapped bolt

[Nebulous]

Yesterday morning checking my bike before going to work I noticed a problem with the back mudguard rubbing. The Torx bolt that holds the rack on also holds the mudguard stay and it was slack, leaving some play. I removed the bolt, which was quite stiff, cleaned and greased it and put it back in. A few turns and it went loose, pulled it out and it has snapped in the hole.

I can remove rack and guard and ride the bike with a backpack in the short term if its dry, but I really need the rack for work.

What do people recommend?

I'm assuming the aluminium alloy at the dropout would be more easily damaged than the remains of the bolt, but I'm considering getting a small metal drill bit and drilling out the end of the bolt. Even if I damaged the threads, as long as the hole was intact I could replace it with a nut and bolt to hold both the rack and stay for the guard in place.

 

[Jamieyorky]

Common problem I'm afraid, its happened to me a few times. Just drill it out and put a nut on the end. If its at the drive side then a small nut is needed so it doesn't catch the chain when it on the bottom ring.

 

[Drago]

Bolt extractor, or get someone with extractors to do it for you.

 

[Gixxerman]

If it is not a blind hole, there may be enough sticking out the other side to get pliers / moled grips onto it so that you can screw it out the back of the hole. If not you could try a small punch to tap it round and drive it out the back of the hole (or front if it is a blind hole). Failing that, you would have to use a stud extractor. These are a coarse threaded tapered screws with a left hand thread and are not too expensive to buy or you may find someone local who can lend you some. Find one that is a few mm in diameter less than then the bolt to be extracted. Mark the centre of the bolt with a centre punch. Try to be as acurate as you can else you risk damaging the thread when drilling. Then get a very small drill bit (2mm or so) and drill a pilot hole. Try to drill as acurately as you can down the centre of the bold keepng the bit straight. Then get a drill bit that is a couple of mm less than the diameter of the bolt to be extracted and drill out the pilot hole to this size. Lubricate the screw as best you can with GT85 / WD40 / easyout / penetrating oil. Screw in the stud extractor (left hand thread) and then using a spanner / socket screw the stud out by screwing the stud extractor in. Take it easy. If for some reason it still won't come out you will have to drill out the hole to as near to the bolt size as you can. You can then remove when is left of the thread using a screw driver and needle nosed pliers. Clean out the thread and check it. If the thread looks ok then add more lube and try screwing a new bolt in / out a few times to re-restablish the thread (this will require a bit of back an forth as you screw the bolt in / out). If the thread is beyond repair you can try running a tap down the hole (a tap is a thread cutting tool and sets can be bought for £20 or so - again someone local may be able to lend you some). If this fails and the thread really is knackered. Then you have to drill it out to the next size by using increasing sizes of drill bit (1 mm at a time) until he whole thread is gone. Then you either re-tap the hole to the new size, or get someone to fit a helicoil for you. You can get helicoil kits, but I have never used them. I leave it to the professionals to fit them. Or you can just save yourself a lot of time, effort and botheration and let the LBS do it for you. They have all the kit and skills as they do this sort of stuff a lot and it shouldn't break the bank either (I'd reckon easily less than a fiver).

 

[Tim Hall]

Buy some Alum (potassium aluminium sulphate) and get cooking like @zigzag did. Linky

 

[Nebulous]

I've got it fixed - (hopefully) but it turned into a bit of a saga.

I went to my LBS, the workshop said I don't fancy drilling that out. The drill will wander and the hole is too close to the edge of the frame, it could very easily burst the hole. I then went to the shop and bought p-clips and a new set of mudguards. Incidentally the new guards say they have a five year guarantee and the old ones were only three years old, so I might have had a warranty claim.

Once I got home I thought, even if it bursts the hole I'll be no worse off than I am at the moment. Drilling it has to be worth a try. If I make a mess of it I can still fit the p-clips anyway. I bought a cheap set of metal drill bits, from 1mm up in 1/2 mm increments. Using the 1.5mm one I managed to drill through, as near as damn it, dead centre. I then went up 1/2 a mm at a time - the 3mm drill bit broke, but apart from this it worked, taking my time, with a lot of pressure needed. By this time the edges of the hole were smooth, with the drill bit and the swarf smoothing them down. I 'tapped' the hole with a couple of spare bolts and it created a thread of sorts.

There wasn't enough room for a nut on the end, without snagging the cassette, so I put a longish bolt through and hacksawed the end off. That has spread the end a bit, meaning it shouldn't pull back through very readily if my makeshift threads give way.

The guard was also very fiddly to fit. The stay is in the way of the disc brake calliper and needed to be bent around it. When I bought the bike I got the guards fitted free and I'm just just now appreciating what that was worth.

That's me, all set-up, ready for my commute today, with a new non-rubbing mudguard. I'll be glad to get the rack back, as carrying a heavy backpack and getting a wet rearend on a couple of occasions wasn't as pleasant as my short commute usually is.

 

[gbb]

I've got it fixed - (hopefully) but it turned into a bit of a saga.

I went to my LBS, the workshop said I don't fancy drilling that out. The drill will wander and the hole is too close to the edge of the frame, it could very easily burst the hole. I then went to the shop and bought p-clips and a new set of mudguards. Incidentally the new guards say they have a five year guarantee and the old ones were only three years old, so I might have had a warranty claim.

Once I got home I thought, even if it bursts the hole I'll be no worse off than I am at the moment. Drilling it has to be worth a try. If I make a mess of it I can still fit the p-clips anyway. I bought a cheap set of metal drill bits, from 1mm up in 1/2 mm increments. Using the 1.5mm one I managed to drill through, as near as damn it, dead centre. I then went up 1/2 a mm at a time - the 3mm drill bit broke, but apart from this it worked, taking my time, with a lot of pressure needed. By this time the edges of the hole were smooth, with the drill bit and the swarf smoothing them down. I 'tapped' the hole with a couple of spare bolts and it created a thread of sorts.

There wasn't enough room for a nut on the end, without snagging the cassette, so I put a longish bolt through and hacksawed the end off. That has spread the end a bit, meaning it shouldn't pull back through very readily if my makeshift threads give way.

The guard was also very fiddly to fit. The stay is in the way of the disc brake calliper and needed to be bent around it. When I bought the bike I got the guards fitted free and I'm just just now appreciating what that was worth.

That's me, all set-up, ready for my commute today, with a new non-rubbing mudguard. I'll be glad to get the rack back, as carrying a heavy backpack and getting a wet rearend on a couple of occasions wasn't as pleasant as my short commute usually is.

You did well. Drilling out a steel bolt in alloy can so easily go wrong, drill skews off into alloy, very hard to stop once it's started.

If it were mine, I'd take that bolt out and get some anti sieze on it, particually as you've cut it which leaves an unprotected end which will rust really easily.