Shimano allen crank bolt stripped -- any ideas?

[Matt O'Toole]

As was probably inevitable, the 8mm allen socket in my Shimano crank bolt is stripped. Any ideas on
how to remove this bolt, other than drilling? How about banging in a Torx bit? Size? Anyone had to
attack this problem recently?

FWIW, these bolts may look neat but I think they're a bad idea. An 8mm allen isn't strong enough to
stand up to the torque a crank bolt might need. The old 14mm standard head bolts were much more
appropriate.

Matt O.

 

[Sheldon Brown]

Matt O'Toole wrote:
> As was probably inevitable, the 8mm allen socket in my Shimano crank bolt is stripped. Any ideas
> on how to remove this bolt, other than drilling? How about banging in a Torx bit? Size? Anyone had
> to attack this problem recently?
>
> FWIW, these bolts may look neat but I think they're a bad idea. An 8mm allen isn't strong enough
> to stand up to the torque a crank bolt might need. The old 14mm standard head bolts were much more
> appropriate.

First try a _brand_new_ 8 mm Allen wrench. It is rare to have this problem except with worn tools.

One of the nice things about Allen wrenches is that they can be sharpened on a grinding wheel, just
grind off the worn-down end. (Make sure to quench in water frequently so the metal doesn't overheat
and get annealed.)

Unfortunately, even a nice fresh Allen wrench won't work once the socket is rounded out. I ran into
this once when this system first appeared.

The ultimate weapon is somethng called an "Easy-out." This is a tool that looks like a tapered tap
with a very steep left-hand thread.

See: http://www.brokentap.com/easy-outs.html

The orthodox way to use Easy-outs is to drill a hole down the bore of the bolt, and then insert
the Easy-out.

In this case, however, I took a larger Easy-out, one that would have been too large to go into the
threaded part of the bolt. I got the largest size that will fit into the stripped Allen socket.
(Sorry, I can't recall what size that is.)

There is no Easy-out that comes in exactly the correct size for this, so the trick is to use the
slightly too-small size, and grind the point off until you get to the part that's thick enough.
Again, make sure to quench frequently.

Sheldon "I Don't Understand How Some People Manage To Live Without A Good Bench Grinder" Brown
+--------------------------------------------------------------+
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+--------------------------------------------------------------+ Harris Cyclery, West Newton,
Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts
shipped Worldwide http://captainbike.com http://sheldonbrown.com

 

[Stu]

if you have a pin punch bigger than the head of the bolt you can try giving the head of the bolt a
nice sharp wack, you my need to hammer the allen key in after, if it pushes some metal back in the
socket. this does two things it makes the hole a little tighter and "can" help break any bond
between the bolt and what it is holding, making it a little easier to undo
p.s. not sure how was the parts near by will respond to the hammering, so its your call

if this dont work there is alway sheldons way

 

[Chris Zacho "Th]

It's very rare for the bolt head to get worn out, unless it's been repeatedly tightened with a worn
hex key (wrench). More than likely it's the key is that's stripped. look at it closely, are the
corners rounded? If so, grind the worn end off (be sure to quench it periodically so it doesn't
anneal (soften).

If that doesn't work, and there are no flats on the outside of the bolt to attach a regular socket
to, you may have to drill a hole in the bolt and try an extractor (Easy-out).

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner

 

[A Muzi]

"Matt O'Toole" <[email protected]> wrote in message
news:[email protected]...
> As was probably inevitable, the 8mm allen socket in my Shimano crank bolt is stripped. Any ideas
> on how to remove this bolt, other than drilling? How about banging in a Torx bit? Size? Anyone had
> to attack this problem recently?
>
> FWIW, these bolts may look neat but I think they're a bad idea. An 8mm allen isn't strong enough
> to stand up to the torque a crank bolt might need. The old 14mm standard head bolts were much more
> appropriate.

Any auto parts house will have a 5/16" allen key to fit a standard 1/2" or
3/8" ratchet handle. I had one because current Chevrolet disc brakes mount with a 5/16" head allen
bolt. That's a pretty handy way to deal with new cranks (8mm to 5/16" is only 0.0025"). I'm
assuming your small allen wrench twists when you're installing the cranks, yes?

I like real bolts, too, but we sometimes have to deal with the world as we find it. A better tool is
a big help rather than trying to talk everyone else into bolts!
--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971

 

[Joshua Putnam]

In article <[email protected]>, [email protected] says...
> As was probably inevitable, the 8mm allen socket in my Shimano crank bolt is stripped. Any ideas
> on how to remove this bolt, other than drilling? How about banging in a Torx bit? Size? Anyone had
> to attack this problem recently?

Get the next-larger size of English-sized hex bit and drive it into the socket with a hammer.

You can actually buy bits for this that have a tapered front, to make them easier to drive into a
socket. Or you can file the face of your ordinary bit yourself.

Both the bit and the bolt are disposable with this approach.

--
[email protected] is Joshua Putnam <http://www.phred.org/~josh/> Updated Infrared Photography Books
List: <http://www.phred.org/~josh/photo/irbooks.html

 

[Benjamin Weiner]

A Muzi <[email protected]> wrote:

> Any auto parts house will have a 5/16" allen key to fit a standard 1/2" or
> 3/8" ratchet handle. I had one because current Chevrolet disc brakes mount with a 5/16" head allen
> bolt. That's a pretty handy way to deal with new cranks (8mm to 5/16" is only 0.0025"). I'm
> assuming your small allen wrench twists when you're installing the cranks, yes?

Sears sells metric allen heads to fit 3/8" ratchet handles, so anyone can get them. I bought some
(actually not from Sears) so I could install crank bolts with a torque wrench. Apparently a lot of
high-end parts now come with torque specs, (stem bolts etc) so a set is a useful thing to have.

I thought the conventional wisdom was that crank squirming up the taper causes the bolt to be
fractionally looser after riding, so it was unlikely that the bolt would be too tight to remove.

> I like real bolts, too, but we sometimes have to deal with the world as we find it. A better tool
> is a big help rather than trying to talk everyone else into bolts!

One nice thing about the allen bolt is that if you needed to do an emergency repair, you might have
an 8mm allen in your seat bag, but not likely a 14mm socket wrench. Maybe that never occurs, but if
if you discover a crank is a little loose during a ride, you might be able to tighten it up before
it's ruined.

 

[David L. Johnso]

On Sat, 19 Apr 2003 22:51:00 +0000, A Muzi wrote:

> I like real bolts, too, but we sometimes have to deal with the world as we find it. A better tool
> is a big help rather than trying to talk everyone else into bolts!

There is an advantage to the allen key bolts, especially the self-extracting ones. On a tour, if you
get caught with a chain that has dropped off the small chainring and jammed itself between the crank
and the frame, then pulling the crank is the best way to go. You might even be able to use the
chain. But who carries a peanut-butter wrench on a tour, much less a crank extractor?

--

David L. Johnson

__o | Do not worry about your difficulties in mathematics, I can _`\(,_ | assure you that mine
are all greater. -- A. Einstein (_)/ (_) |

 

[Mixedkid]

I've never specifically dealt with this problem but I've run into it in other applications. In that
situation I used solder to fill in the gap between the wrench and stripped bolt. In this case you'd
actually want to have a poor or cold joint. You actually don't want the solder to bond to anything.
It should just be filling space. So you can heat the solder and drip it into place but don't heat
the allen wrench or the bolt. It should work as long as the inside of the bolt isn't perfectly
round. Even if it does bond to something you can just heat it up again and get it off. I agree that
the extractor bits are a good idea but I always hate to mutilate tools just for one project. Or if
you don't have a bench grinder or dremmel tool handy. Good luck

Joshua Putnam <[email protected]> wrote in message news:<MPG.190bc4dca2ccdc6a989697@localhost>...
> In article <[email protected]>, [email protected] says...
> > As was probably inevitable, the 8mm allen socket in my Shimano crank bolt is stripped. Any ideas
> > on how to remove this bolt, other than drilling? How about banging in a Torx bit? Size? Anyone
> > had to attack this problem recently?
>
> Get the next-larger size of English-sized hex bit and drive it into the socket with a hammer.
>
> You can actually buy bits for this that have a tapered front, to make them easier to drive into a
> socket. Or you can file the face of your ordinary bit yourself.
>
> Both the bit and the bolt are disposable with this approach.