Larry,
when mine sheared off I went to Sears and purchased a set of bolt extractors
that have a drill built into them. You run them in reverse and they drill
and then you screw a collar into the hole and it grabs and backs it out. I
broke one trying to do it, but the second try worked.
I was concerned about when I tried drilling the bolts I'd actually screw
them down into the tapped end of the crank, and not be able to reach them
with my ease out. I was also told that a left handed drill bit (one that
drills in the counter clock-wise direction) would do the same because it
would be putting pressure on the bolt to unscrew it as you drilled.
I was also told by a fellow who works on many types of mechanical systems
that once the tapped threads have been stretched, they will never be the
same for holding the bolts.
Charly
----- Original Message -----
From: <mporter@zianet.com>
To: "Larry Young" <cartravel@pobox.com>
Cc: <fot@autox.team.net>
Sent: Tuesday, October 07, 2003 6:12 PM
Subject: Re: Another Wayward Flywheel
> Larry Young writes:
>
> > My car succumbed to the loose aluminum flywheel problem this past
weekend
> > at Hallet. There was no major harm done, it just sheared the bolts and
> > slid back on the transmission input shaft. Does anyone have any tricks
> > for removing broken grade 8 bolts? I've tried to drill them in order to
> > use an easy out, but a standard drill bit doesn't cut it. Any
suggestions
> > will be greatly appreciated.
>
> If there's enough sticking out, file the stub flat, centerpunch it, then
try
> drilling with a TiN-coated drill bit (with this, try to maintain steady,
> firm pressure--too light a pressure and the coating is worn away). If that
> doesn't work, about all that's left is a carbide drill. Carbide will do
it,
> but it's _very_ brittle and doesn't tolerate bumps or side loads.
>
> In the case of either drill, it's advisable, if the bolt is broken off
below
> the surface of the hole, to find or make a drill guide. Otherwise, trying
to
> get a reasonably straight hole into the bolt is rather difficult.
>
> Cheers.
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