Sheared screw - help please!

maloflora

Pedelecer
Nov 13, 2012
40
1
Hi all,

I've been happily using a KTM Macina Sport for the last 18 months with no problems. However, the screw that holds the rack and mudguard to the frame has suddenly sheared off, leaving a broken bit behind that I can't get out (pics attached).

I went to a bike shop this afternoon, who said 'bike shops don't do this kind of repair any more. Too time-consuming and risky'. Is that really right? Or do I need a better bike shop?

Thanks for any help!
 

Attachments

trex

Esteemed Pedelecer
May 15, 2011
7,703
2,671
Take a look at the broken bolt from the wheel side. If there is enough thread, you may just be able to use a 6mm bolt and turn it in gently from the wheel side, you may just get lucky, the new bolt is going to spin the broken bolt out for you. Don't use force, you may damage the thread. Another solution is to drill out the broken bolt from the wheel side with a 4mm carbide drill bit.
 
D

Deleted member 4366

Guest
Have you got a Dremmel? If so, put on one of the thin cutting discs and cut a slot right across the middle. You'll then be able to screw it out with a screwdriver.
 
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markrl

Finding my (electric) wheels
Nov 18, 2014
14
7
London
Take a look at the linked YouTube video demonstrating the use of an Easyout extractor.

 

Fordulike

Esteemed Pedelecer
Feb 26, 2010
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Have you got a Dremmel? If so, put on one of the thin cutting discs and cut a slot right across the middle. You'll then be able to screw it out with a screwdriver.
+1

This will definitely work if you have enough bolt still poking out. I'll add that once you have cut the slot in the face, then spray a little penetrating oil on the thread to help ease the bolt out.
Squirt it from the other side, so it really works into the thread.

Been there, done that on a bolt that did the same thing on a car.

A Dremmel is one of the best investments you can make. Really really handy little machines, with attachments available for every conceivable situation.
 
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maloflora

Pedelecer
Nov 13, 2012
40
1
Thanks for the suggestions. I'm not really that experienced at this kind of DIY. From the pictures I uploaded does it look like I could use the Dremel method? I think it may be a bit too flush with the frame.

I can't get to the bolt from the other side alas - the brake disk is in the way and I've never taken one of those off.
 
D

Deleted member 4366

Guest
It looks like you've got enough for the slot method. You might end up with a couple of nicks either side, but nobody will notice when the rack's back on.

Don't use an Ezee-out. It'll snap, and then you're out of the game. The same with drilling. On small screws like that, it's too easy to break the drill, then you're out as well. The slot method is the safest.
 

mike killay

Esteemed Pedelecer
Feb 17, 2011
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A bike shop that cannot remove that bolt has no business calling itself a bike shop. Try a local garage.
 

markrl

Finding my (electric) wheels
Nov 18, 2014
14
7
London
Because the bolt has sheared off flush with the surrounding surface if you attempt the Dremel method I think there's a risk you could damage the surrounding area particularly if your not skilled in that type of work. I would personally invest in a set of easyout extractors and take that route. Failing that I really cant see why a competent bicycle repair shop couldn't carry out the repair. Which ever route you take there is of course some risk.
 
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maloflora

Pedelecer
Nov 13, 2012
40
1
Brill - thanks all. Thought it should be a reasonable repair to ask a shop to make! I'll try a better shop next weekend and see how we get on. Until then cable-ties for the mudguard will have to do!
 
D

Deleted member 4366

Guest
I would personally invest in a set of easyout extractors and take that route.
Have you ever successfully managed to get a small bolt out with an Easyout?

Everybody I know that tried, including myself (stupidly, several times), broke it in the bolt, which rendered the item unrepairable.
 

D C

Esteemed Pedelecer
Apr 25, 2013
1,140
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I would suggest you just drill it out using a similar size drill bit without worrying about the thread, then replace with a new loose bolt and nylock nut.
I think it would be worth doing the same to the other side whilst you are at it as that side may be ready to shear as well, particularly having now taken all the weight. That way you won't have the same problem in future.
I realise you are unhappy removing the wheel but maybe you could use this as an opportunity to learn how to do so, it's not hard and you will get advice here.
I wonder if any forum member with DIY skills lives near you or perhaps as Mike said, maybe a small local garage would do it, it's an easy fix.
A bike shop really can't be considered to be a bike shop if they can't do this sort of job, what do they expect you to do. throw it in a skip?
Dave.
 

Scott clarke

Pedelecer
May 5, 2015
215
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I've never had any luck with easy out what I did when I had a bolt break off flush was drill a hole from the opposite side put a large head self tapping screw into the hole and screwed it in and when it got tight it started unscrewing the bolt until it was out far enough for me to grab it with mole grips.
 

markrl

Finding my (electric) wheels
Nov 18, 2014
14
7
London
Have you ever successfully managed to get a small bolt out with an Easyout?

Everybody I know that tried, including myself (stupidly, several times), broke it in the bolt, which rendered the item unrepairable.
Yes I have but I fully accept your point about the risk of either it or the drill breaking. If the sheared bolt was rusted solid or completely jammed due to cross threading then I would certainly have second thoughts about using an easyout. But if that was the case I don't think the Dremel route would work either and of course sods law has kicked in and the bolt has sheared off flush with the surrounding surface.
It really depends on how tightly its jammed.
 

flecc

Member
Oct 25, 2006
52,763
30,349
Have you ever successfully managed to get a small bolt out with an Easyout?

Everybody I know that tried, including myself (stupidly, several times), broke it in the bolt, which rendered the item unrepairable.
And me, done it twice but never again. Easyouts are generally useless with small bolts due to snapping before the bolt thread releases.
.
 

oldtom

Esteemed Pedelecer
Good quality screw extractors will not break if used sensibly - like drills, taps and dies, there are crappy ones and there are very high quality ones.

Only recently, I had to remove a motor mounting screw from my old lawnmower and because it was sub-surface, cutting a new slot wasn't possible. Fortunately, after a hunt through my sheds, I found my case of screw-extractors and drilled into the screw body sufficiently to allow the CORRECT SIZE extractor to get some grab and it duly came out.

It is difficult sometimes to remove screws if they have snapped sub-surface but if there is the possibility to get a drill bit on the centre of the screw or bolt body, (centre punch can help) careful drilling using increasing diameter bits can usually clean out enough meat to allow a metal-tipped probe of some kind to break away the last remnants of the thread with no damage to the female thread. On some occasions, a wispy coil of thread can actually be unscrewed using something like the tang of a file.

I deliberately emphasised the part about screw extractor size because it's really important to drill the right size of hole for a particular extractor. There's no magic involved - it's just a matter of care and accuracy.

Tom
 
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C

Cyclezee

Guest
This might sound nuts and bit of a long shot, do you know a dental technician? If not take Oldtoms' advice.

If there is no space to cut a slot for a flat blade screwdriver because it has broken off flush, dental technicians have high speed micromotors (a sophisticated Dremel AKA handpiece) along with tungsten carbide and diamond tipped burs that will cut into anything, cobalt chromium, titanium etc., so a precise slot could be cut in the remaining part of the bolt without damaging the surrounding area.

One more question, what caused the bolt to shear like that?
 

RobF

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Sep 22, 2012
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Kuorider

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Jun 18, 2014
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Easy- outs are rubbish, don't even think about it. If you can drill the bolt or stud for an easy- out you can easily continue to drill out with larger drills until only the thread is left. This can then be picked out with a sharp point. This is NOT a job for your Black and Decker and B&Q drill set. Check the bolt size then the drill tables for the tapping size for that thread ,job done. Find someone who can do this for you, a small local garage is the best bet as broken bolts, rusted threads etc on cars are regular jobs. Post your location as someone may be able to help. If near me bring it round and I will have it out in five minutes. Many an honest pound I made sorting out easy- out fek-ups on expensive parts in the good old days. Worst case cure was to cut out the mess and Helicoil it. Worth the bother on an expensive frame.

If you manage to cut a slot, tread carefully, soak overnight with penetrating oil, if the bolt does not turn easily, stop, as some heat will be needed, best is a small gas torch. Heat it a little at a time and allow to cool ,repeat, . If it moves, unscrew a turn or two then re tighten a little ,repeat until it runs free. If this does not work do not chew up the slot and get help. A chewed up bolt is harder to drill accurately and becomes a bench job. After it's out replace it with an allen bolt ,these don't break so easily.
.
 
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