[Public-List] broken motor mount bolts

[Kris Coward]

On Tue, Apr 05, 2011 at 03:32:02PM -0400, Don Campbell wrote:
> Has anyone had experience removing sheared motor mount bolts from the  
> logs to hold the motor? I have one sheared off at the top of the  
> fiberglass that needs to come out and am looking for ideas to gt it out.  
> Does anyone know what the bolts are threaded into, a nut embedded or a  
> plate of steel embedded in the log?

I'm pretty sure that it's a plate. I had some sheared bolts to remove 6
years ago (so my memory's a little fuzzy on it). I first tried with a
large "screw extractor" (the ones that are basically a cross between a
tap and a screw, with a very steep left-hand thread) in theory, you
drill a pilot hole in the screw to be extracted, start turning in the
extractor until it's can't go in any farther and starts passing the
torque to the screw from the inside (along those steep threads). In
practice, the things are pretty brittle and are just as likely to shear
off themselves as they are to remove the bolt.

After shearing mine off inside the bolt, I ground it and the bolt out
with a die grinder, got an appropriately-sized helicoil, redrilled and
retapped the hole to take the helicoil. I then greased the hell out of
the thread and switched to stainless bolts. Haven't had a problem since
(though I also haven't tried to pull the engine since, so...)

Cheers,
Kris

-- 
Kris Coward					http://unripe.melon.org/
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