Drilling out sheared off bolts.

Nov 16, 2005 51 Replies

Buy suitable sized bolt extractors and use those. They look a bit like tapered screws with a coarse, reverse thread. You drill a hole into the centre of the bolt, screw in the bolt extractor and as it tightens up, it undoes the bolt. , assuming it isn't well corroded in place.

I last used these to remove the Philips-headed bolts from the allow crankcase of a Honda motorcycle gearbox - which meant being very careful!

well its not if you happen to have the correct size to hand (extremely unlikely), but non aristocrats would try a stud extractor first.

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8mm - the question was a general one, really, so I'm still interested in techniques!

Whatever the method of finally turning the stud, serious heat on the assembly is useful. The expansion helps to break the seal and/or soften whatever gunge is holding the threads together.

The message from Chris Bacon contains these words:

A friend and I once sheared off a head-bolt in his Morris 1100 A-series engine. we couldn't get it out so we drilled to a larger size and tapped for a bolt, wound it in with thread sealant then drilled and tapped that back to the original size. Worked fine, took an hour or so.

Hi,

I'd try tapping a normal (ie right hand) threaded hole in the stud then use a high tensile bolt and some Loctite threadlock of the "bloody well permanent" variety.

Some JB weld and an allen key or torx bit in a clear hole may work.

cheers, Pete.

I know some people tap in a torx or spline bit instead of a proper stud extractor, seems to work ok.

mrcheerful

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Bought a set of these a couple of years ago. They haven't let me down yet, work fine.

John

At that size, I would go for the way mrcheerful states. I did this, using a torx bit, on a car steering lock break off bolt and it worked a dream.

A poor mans timesert , beats helicoils.

Or just buy a stud extractor, which is essentially the same thing...a reverse threaded self tapping screw that takes a wrench on its head...

Heat and WD40 or equivalent often breaks the corrosion.

Yes you can use this tool just the same BUT the tap and die comes in handy at some time or other for creating a left handed thread, whereas the stud extractor might never get used again. :-)

-- Sir Benjamin Middlethwaite

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