locking wheel nut sheared (citroen c3)

Stephen gurgled happily, sounding much like they were saying:

Makes sense - after all, a security bolt which could be easily defeated wouldn't offer a lot of security, would it?

Drilled it out, probably.

Dynomec make a nice kit for the purpose, if you've not got rotating collars then everybody & their dog sells internally threaded sockets that work eventually.

But how can the bolt "tell" that it is being screwed backwards by an emergency socket rather than the security "key"? I only unscrewed it by hand so I wouldn't have used more force than with the standard wheel brace.

What sort of metal are these bolts made from? Would you need a hard left handed drill bit to drill it out? I wasn't sure whether drilling would work because if it had been over tightened by an air gun, would a drill be able to supply that much torque?

They gave me the bolt back and it is chewed up at the 9 o'clock and 3 o'clock (or is it 6 and 12 ;)) positions so it looks like something was attached there. There are not any visible drill holes. There's also the matter of the chips on either side of the alloy wheel. A drill would not have touched these points. I'm sure there's a bit more magic involved!

That's what I used but it sheared the head of the nut off.

this kit does the job without damage:

AT that point you're stuck with using a Dynomec or a left hand drill bit.

That dynomec set looks like a very useful addition to the toolbox.

Thanks. I am pretty sure they didn't use dynomec because from reading the url given in another reply, it seems that the dynomec has a soft metal sleeve that deforms around the remains of the bolt. I didn't really have anything left for a dynomec to surround: it was more or less a flat disc by the time I had sheared off the top. I think they must have drilled it.

I have seen left handed bits but I don't know what metal they were made from. Would they drill into a wheel bolt or are the bolts too hard? Would you need a cobalt steel bit?

That said, I've searched the net and found people selling extractor sets which include a cobalt bit that is right handed to make the hole and then a left handed extractor in another metal to remove the bolt. Don't cobalt LH bits exist, that would cut out a step and make things quicker.

Thanks, Stephen.

I did have two chewed-up areas on the bolt, so perhaps that's where they hammered something in?

Thanks. The links you gave were for HSS bits. Will they drill into the bolts? Being a security bolt,I thought they may have been made of harder steel to prevent drilling, requiring a cobalt steel bits?

I have taken the other three security bolts off and replaced them with normal ones. When I've got time, I may try and drill these to see if a HSS bit will work. What's the trick: to use the biggest bit that you can?

Thanks, Stephen.

Yup, sharp bit , plenty of lubrication & make a dimple in the centre with a centre bit. But most security bolts aren't that hard.

No start with the smallest bit that you can use without it bending then use one slightly smaller than the bolt shank.

But IMHO utterly pointless as they just drill a hole exacly like a normal drill. If they snag then you might get some slight effect but as a bolt removal method or a means of even slighly loosening a bolt they are about as good as snake oil.

Works for me nearly every time, maybe I just push harder. They nearly always snag (I'm actually failing to remember the last time one didn't).

it is a combination of effects, removing metal relieves pressure on the threads and the vibration/snagging drags the bolt in the right direction. You get the same effect with a normal drill bit, but of course the broken bit goes in further, but that is good if it is a through bolt with rust on the exposed threads. The other way which can be quite useful on large bolts is to drill straight down the threads with a small drill bit, then pour in some penetrating oil , drill down the middle as usual to remove , the thread hole lets penetrating oil get right round all the hidden threads and acts like a thread chaser as the broken bit comes out. I have often found that the best thing to knock into the hole to give leverage to undo is a Torx bit, it gives grip without spreading the drilled broken stud/bolt

Hi All,

With regard to the "Dynomec" tool, it occurs to me that *maybe* the force used to deform the top of the sheared bolt / screw might damage the suspension and or the mounts. I would imagine that the vehicle would be on a lift to enable the mechanic a good hard swing. The impact would be off the centre line of the stub axle, and some of the force of the impact (not all would be absorbed by the deformation of the stuck shaft) transferred to the suspension components.

I think I would rather drill out the remains of the wheel bolt.

regards

David

Compared with driving down the road it's pretty negligible force:-)

I do not entirely agree; driving down the road will not give a side impact at such force, unless one understeers into a kerb with the wheel turned. I've done that and bent the wishbones and mounting bolts, about 22 years ago ;-)

Are you telling me that the suspension is designed to absorb a sideways smack ? If it was, then the impact would have very little effect on the sheared bolt.

regards

David

I realise I am closing the door after the horse has bolted but in anticipation of next time, what do you think is the best thing to have on standby?

I've looked at the URLS in earlier replies for left handed drill bits, thanks.

I have also found these: right handed drills with left handed extractors 1-5mm:

And there seem to be several Irwin sets of "reverse spiral", which seems to me to be another way of saying "left handed", like this: The only difference that I can see between the various Irwin sets is the sizes; there are big sets to be used in wrenches and ratchets on big nuts down to small drill-driven sizes for small nuts. To get them all seems an expensive way of doing things. Would the left handed bits or the axminster set be a cheaper way of protecting myself from similar problems in the future?

Thanks, Stephen.

I was just re-reading the replies and I notice to mention left handed bits and then say centre drill bits are better. Sorry for being thick but what is a centre bit and how is it different from a left handed bit. I read the URL but that suggests that centre bit is left handed so I am very confused!

Thanks, Stephen.

Thanks. I was worried that using the smallest one might result in it snapping and making the problem worse but having re-read your reply, I see that you qualified that by saying the smallest that will not bend so that makes sense.

I wasn't sure whether a small bit would provide enough torque to undo a wheel nut that had been over tightened by an air gun?

I suppose that by going up through the sizes you get more chances, whereas if you start with the biggest bit you have, you only get one go?

Thanks, Stephen.