Ruined allen socket head on a crank bolt. How to remove?

stuck bolt, yuck:

consider this as last ditch desperation advice, unless someone with more
than half a brain supports it:

take the bike to a reputable auto repair place, ( i would take it to
someone that specializes in bmw, but thats just cause i have found they
all seem to really know thier stuff )

have them use the mig welder and weld a nipple on the end of the screwed
screw. this will allow you to use a pair of vice grips to spin it with
the advantage that the heat transfer into the bolt will help break it
free from being seized.

this is comonly done in engine blocks and etc when you break a head
bolt. the heat transfer to the bottom bracket spindle and the crank
should be miminal, as MIG is used when welding heat treated metal
without taking the temper out of it.

Mr. Bill

Michael Slater said:

The bottom bracket of my Trek Liquid 20 is making a cracking noise. My
first guess, and the Barnett Guide's advice is that it's most likely a
loose crank. (This has happened to me before on other bikes).

Today I decided to remove the cranks and then re-tighten them. In
preperation, I even bought a torque wrench so that I can tighten the
cranks to the correct specification.

Not thinking clearly, I removed the cranks from the wrong Liquid 20.
Didn't really matter, I'll regrease and re-tighten them too. But then
I realized I'd made another mistake. When I bought the torque wrench I
forgot to get a 3/8" square to 8mm allen key socket. The 8mm allen key
is needed to remove the crank bolt that holds the crank tight against
the splines of the bottom bracket. This precludes me from retightening
the cranks to the correct torque.

Oh well, I might as well remove the cranks from the second (creaking)
bike. First one came off fine. The second one was a serious nuisance.
For some reason I couldn't get good purchase and it wouldn't budge.
Then I noticed that the allen wrench was slipping. Before long I can
see that the allen key head of the bolt is rounded off and I can't get
any purchase on the bolt. It's stranded. I'm screwed.

I took the bike to a local bikeshop that seems happy to get down and
dirty. After I refused the guy's offer to "do a total rebuild of the
bike -- take it all apart put it all back" (it doesn't need it) I
think he grew cold on me. And when I came back thirty minutes later
said it was impossibly stuck and my best bet was to chisel it out. For
heaven's sakes.

I've seen references to adjustable pin spanners, but the torque
necessary to break free the crank bolt from the bottom bracket is
immense. I can't imagine them standing up to the task.

So two questions?

1) How do I get this bolt out? Currently my only idea is to have
someone weld a socket directly on the bolt that I can torque free.

2) Where do I find a replacement crank bolt?

[email hidden]

Would welding heat up and destroy everything in the area? How about
drilling out the bolt head, removing the crank and then using a
gripvise on what's left of the bolt. You probably would mess up the
crank a bit when drilling out the head.

[email hidden] (Michael Slater) wrote in message news:<[email hidden]>...

Quoted message said:

So two questions?

1) How do I get this bolt out? Currently my only idea is to have
someone weld a socket directly on the bolt that I can torque free.

2) Where do I find a replacement crank bolt?

[email hidden]

"Michael Slater" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

The bottom bracket of my Trek Liquid 20 is making a cracking noise. My
first guess, and the Barnett Guide's advice is that it's most likely a
loose crank. (This has happened to me before on other bikes).

I've seen references to adjustable pin spanners, but the torque
necessary to break free the crank bolt from the bottom bracket is
immense. I can't imagine them standing up to the task.

pin spanners are commonly used on cup and cone bottom brackets. I wouldn't
count that option out.

--
Derek Hodges
Toronto

Woogoogle said:

Would welding heat up and destroy everything in the area?

MIG welding doesnt use any flame so the heat is extremely localized.
my guess is the crank wouldnt heat up much at all, and would not become
hot enough to burn your fingers

the heat will only to into the bolt directly, although some will be
transferred to the bottom bracket spindle and the crank but not that
much.

Mr. Bill

Woogoogle said:

Would welding heat up and destroy everything in the area?

MIG welding doesnt use any flame so the heat is extremely localized.
my guess is the crank wouldnt heat up much at all, and would not become
hot enough to burn your fingers

the heat will only to into the bolt directly, although some will be
transferred to the bottom bracket spindle and the crank but not that
much.

Mr. Bill

Michael Slater said:

Oh well, I might as well remove the cranks from the second (creaking)
bike. First one came off fine. The second one was a serious nuisance.
For some reason I couldn't get good purchase and it wouldn't budge.
Then I noticed that the allen wrench was slipping. Before long I can
see that the allen key head of the bolt is rounded off and I can't get
any purchase on the bolt. It's stranded. I'm screwed.

Quoted message said:

1) How do I get this bolt out? Currently my only idea is to have
someone weld a socket directly on the bolt that I can torque free.

I once ran into one of these that had been wrecked by a worn-out Allen
wrench. In the end, I used a tool commonly known as an Ezy-Out, or
generically, as a "screw extractor." This is a tool that looks sort of
like a left-hand threaded tap, with tapered helical grooves.

The normal way to use an Ezy-Out is to drill a specific sized hole into
the bolt then insert the Ezy-Oyt. However, I didn't believe that an
Ezy-Out skinny enough to fit into the bolt shaft would be strong enough
to undo this particularly recalcitrant bolt. I also didn't relish
trying to drill out the bolt.

Instead, I used a considerably larger Ezy-Out, the biggest one that
could fit into the remains of the 8 mm Allen socket. (Sorry, I don't
recall the specific size.) The Allen socket is not so deep, so the
largest size that would fit in was too loose to even get close to
getting a grip.

I got around this problem by grinding the point of the Ezy-Out off. You
need a serious bench grinder for this, and it is important to quench the
Ezy-Out very frequently in water so it doesn't overheat and anneal the
hardened steel it's made of.

This took a while, but in the end it worked.

Quoted message said:

2) Where do I find a replacement crank bolt?

Any bike shop.

Sheldon "Sparky" Brown
+-------------------------------------+
| Don't drink and drive: you might |
| hit a bump, and spill your drink! |
+-------------------------------------+
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

Michael Slater said:

The bottom bracket of my Trek Liquid 20 is making a cracking noise. My
first guess, and the Barnett Guide's advice is that it's most likely a
loose crank. (This has happened to me before on other bikes).

Today I decided to remove the cranks and then re-tighten them. In
preperation, I even bought a torque wrench so that I can tighten the
cranks to the correct specification.

Not thinking clearly, I removed the cranks from the wrong Liquid 20.
Didn't really matter, I'll regrease and re-tighten them too. But then
I realized I'd made another mistake. When I bought the torque wrench I
forgot to get a 3/8" square to 8mm allen key socket. The 8mm allen key
is needed to remove the crank bolt that holds the crank tight against
the splines of the bottom bracket. This precludes me from retightening
the cranks to the correct torque.

Oh well, I might as well remove the cranks from the second (creaking)
bike. First one came off fine. The second one was a serious nuisance.
For some reason I couldn't get good purchase and it wouldn't budge.
Then I noticed that the allen wrench was slipping. Before long I can
see that the allen key head of the bolt is rounded off and I can't get
any purchase on the bolt. It's stranded. I'm screwed.

I took the bike to a local bikeshop that seems happy to get down and
dirty. After I refused the guy's offer to "do a total rebuild of the
bike -- take it all apart put it all back" (it doesn't need it) I
think he grew cold on me. And when I came back thirty minutes later
said it was impossibly stuck and my best bet was to chisel it out. For
heaven's sakes.

I've seen references to adjustable pin spanners, but the torque
necessary to break free the crank bolt from the bottom bracket is
immense. I can't imagine them standing up to the task.

So two questions?

1) How do I get this bolt out? Currently my only idea is to have
someone weld a socket directly on the bolt that I can torque free.

2) Where do I find a replacement crank bolt?

[email hidden]

Get a stripped bolt extractor kit ;-)

Basically a hardened screw with a left-hand thread. Drill a small hole
and screw the tool in. The bolt will come out.

Replacement crank bolts are widely available in aluminium, but these are
useless for actually fitting cranks (they work OK for holding them in
place once they have been torqued up with a steel bolt). Anyway, the
good news is that most bottom brackets use standard M8 threaded bolts,
so you can use one of those (with a suitable washer to protect the
crank), fit the crank, then remove and replace with the alu bike jewellery.

On 11 Sep 2004 03:53:58 -0700, [email hidden] (Michael

Slater) said:

So two questions?

1) How do I get this bolt out? Currently my only idea is to have
someone weld a socket directly on the bolt that I can torque free.

Hazardous and inadvisable. I would use a drill with a 5/16" or larger
(but preferably not over 3/8"😉 bit to drill through the bolt head. If
you can find a reverse-twist bit, it will have a good chance of
grabbing the bolt and spinning it out. If the recess is well and
truly stripped, a 21/64" drill bit should center up nicely in it and
neatly remove the bolt head. If an 11/32" will fit in the stripped
recess, that's just as good and possibly better.

Quoted message said:

2) Where do I find a replacement crank bolt?

Any decent lbs should have them. Any serious DIY bikeaholic probably
has several in the junk box.

In your situation, while I was at it, I'd replace both bolts with some
that aren't socket-headed...but that's just me.
--
Typoes are a feature, not a bug.
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Zog The Undeniable said:

...Anyway, the
good news is that most bottom brackets use standard M8 threaded bolts,

Ahem. M8 fine thread. That's M8x1.0 The more common size of M8 is
the M8x1.25, which most hardware stores have. I have found few
hardware stores in the US have 8x1.0 stuff, but far too many of them
have brain-dead staff who will look at the bolt and incorrectly
identify it as 5/16NF, which it closely resembles. Buying this bolt
at the lbs is a good idea in my opinion.

Quoted message said:

so you can use one of those (with a suitable washer to protect the
crank), fit the crank, then remove and replace with the alu bike jewellery.

Eh, I suppose, but I figure that substance overrules form, so I just
go with the appropriate steel bolt and knock the plastic cap in to
cover it.

--
Typoes are a feature, not a bug.
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Sheldon Brown said:

Michael Slater said:

Before long I can
see that the allen key head of the bolt is rounded off and I can't get
any purchase on the bolt. It's stranded. I'm screwed.

Quoted message said:

1) How do I get this bolt out? Currently my only idea is to have
someone weld a socket directly on the bolt that I can torque free.

I once ran into one of these that had been wrecked by a worn-out Allen
wrench. In the end, I used a tool commonly known as an Ezy-Out, or
generically, as a "screw extractor." This is a tool that looks sort of
like a left-hand threaded tap, with tapered helical grooves.

Another approach would be to drill out the socket with a drill at
least 8mm in diameter (preferably a little bigger) until the bolt head
comes off the thread. After the fastener's tension is released, the
stub remaining in the spindle should turn out with no significant
torque required.

Left-handed drill bits are especially good for this because they tend
to spin the fastener out as soon as the tension releases.

Chalo Colina

Werehatrack said:

Ahem. M8 fine thread. That's M8x1.0 The more common size of M8 is
the M8x1.25, which most hardware stores have.

My mistake - and I was the one going on about "M5" and "M5 fine" the
other day...

Michael Slater said:

The bottom bracket of my Trek Liquid 20 is making a cracking noise. My
first guess, and the Barnett Guide's advice is that it's most likely a
loose crank. (This has happened to me before on other bikes).

Today I decided to remove the cranks and then re-tighten them. In
preperation, I even bought a torque wrench so that I can tighten the
cranks to the correct specification.

Not thinking clearly, I removed the cranks from the wrong Liquid 20.
Didn't really matter, I'll regrease and re-tighten them too. But then
I realized I'd made another mistake. When I bought the torque wrench I
forgot to get a 3/8" square to 8mm allen key socket. The 8mm allen key
is needed to remove the crank bolt that holds the crank tight against
the splines of the bottom bracket. This precludes me from retightening
the cranks to the correct torque.

Oh well, I might as well remove the cranks from the second (creaking)
bike. First one came off fine. The second one was a serious nuisance.
For some reason I couldn't get good purchase and it wouldn't budge.
Then I noticed that the allen wrench was slipping. Before long I can
see that the allen key head of the bolt is rounded off and I can't get
any purchase on the bolt. It's stranded. I'm screwed.

I took the bike to a local bikeshop that seems happy to get down and
dirty. After I refused the guy's offer to "do a total rebuild of the
bike -- take it all apart put it all back" (it doesn't need it) I
think he grew cold on me. And when I came back thirty minutes later
said it was impossibly stuck and my best bet was to chisel it out. For
heaven's sakes.

I've seen references to adjustable pin spanners, but the torque
necessary to break free the crank bolt from the bottom bracket is
immense. I can't imagine them standing up to the task.

So two questions?

1) How do I get this bolt out? Currently my only idea is to have
someone weld a socket directly on the bolt that I can torque free.

2) Where do I find a replacement crank bolt?

Drill the bolt out. Use a screw/drill extractor to remove the pieces
that are left over.

Regarding the crank bolt....

The bolt is approximately 15mm in diameter, with a flanged head
perhaps 19mm wide. The issue is, the bolt is not solid. The walls of
the bolt are 2mm thick. The flange is only about 3mm thick,
separating the hollow underbody of the bolt and allen-key head a the
top.

So the question is, what exactly am I supposed to drive the bolt
extactor into?

If I drill it just through the allen key head, it's only grabbing 3mm
of meat that separates the allen key and the underside, plus the few
mmm of meat in the allen key head. I'm concerned that might not be
enough grip to back crank bolt out. Is it?

Or are people advising I use a very big extractor that also carves
into a little bit (but not too much!) of the 2mm walls that make up
most of the bolt. This seems like a very fine operation to perform
successfully.

On 13 Sep 2004 20:40:05 -0700, [email hidden] (Michael

Slater) said:

Regarding the crank bolt....

The bolt is approximately 15mm in diameter, with a flanged head
perhaps 19mm wide. The issue is, the bolt is not solid. The walls of
the bolt are 2mm thick. The flange is only about 3mm thick,
separating the hollow underbody of the bolt and allen-key head a the
top.

So the question is, what exactly am I supposed to drive the bolt
extactor into?

If I drill it just through the allen key head, it's only grabbing 3mm
of meat that separates the allen key and the underside, plus the few
mmm of meat in the allen key head. I'm concerned that might not be
enough grip to back crank bolt out. Is it?

Or are people advising I use a very big extractor that also carves
into a little bit (but not too much!) of the 2mm walls that make up
most of the bolt. This seems like a very fine operation to perform
successfully.

Wait a minute, is this a conventional crank bolt we're talking about,
or are these self-extracting cranks, with a crank bolt like this:

http://www.sandsmachine.com/ac_bolt.htm

If so, then yes, things are a bit more complicated, and extraction
without destruction is preferable...but the place to start is with
extracting the cap and washer (which likely requires a pin spanner)
and then, if the crank has threads that will allow the use of a crank
extractor, it's still best (in my personal opinion) to drill the head
off the bolt and replace it with a conventional non-self-extracting
version unless and until you can get the preferred type.

If it's just a regular crank bolt, then the threaded shaft of the bolt
should be about 8mm in diameter, and if you drill through the head of
the bolt with a slightly larger drill bit, centering on the stripped
Allen recess, you'll remove the head cleanly from the shaft of the
bolt without damaging anything else. At that point, a crank extractor
will take the crank off the BB, and if the shaft of the bolt can't be
easily unscrewed from the BB with a pair of pliers, then you're in
position to be able to replace the BB as a worst-case scenario.

Trying to use a screw extractor on a shallow hole is, I agree,
potentially a very frustrating process. That's why I wouldn't bother
with it. But trying to weld something to that bolt head down inside
the crank recess strikes me as a stunningly efficient way to
accidentally bugger the crank extractor threads...and if the screw is
part of a self-extractor, welding something to it is still courting a
slip that will make the crank a candidate for the recycling bin.

Remember; the bolt is already useless, so you aren't destroying
anything useful if you drill the head off of it...and with any
reasonable amount of care and skill in drill usage, that bolt head
will come off without doing anything of consequence to the BB shaft or
the crank.
--
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In article <[email hidden]>,

(Michael Slater) said:

1) How do I get this bolt out? Currently my only idea is to have
someone weld a socket directly on the bolt that I can torque free.

An idea I saw here, but have never had to try, is to epoxy that allen wrench
into the bolt and let it set up. If it works you are only out the wrench, if
it doesn't work you have a somewhat bigger problem on your hands.

Tom Gibb <[email hidden]>

(TBGibb) said:

In article <[email hidden]>,

(Michael Slater) said:

1) How do I get this bolt out? Currently my only idea is to have
someone weld a socket directly on the bolt that I can torque free.

An idea I saw here, but have never had to try, is to epoxy that allen wrench
into the bolt and let it set up. If it works you are only out the wrench, if
it doesn't work you have a somewhat bigger problem on your hands.

You just reminded me of a trick I saw used once long ago. A stripped
allen-head bolt was removed by taking a flat-ended punch and tapping
on the rim of the head to collapse the raised edges back into the
recess, after which the regular Allen wrench was able to get the bolt
to turn. Beating on the rim of the bolt both partially re-formed the
hex and loosened the bolt enough that it would back out. I'd want to
buck the other end with a big punch and large weight. or support it
against a stationary object, if I was going to try this on a crank
bolt.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.