Stuck crank blues

OK, people, let's have your favourite cures for stuck cranks. I am faced
with a Halfords Carrera hardtail. It has a horrible irregular noise from
the bottom bracket when pedalling - so horrible that I first suspected a
cracked frame, but I can't find any cracks. The bottom bracket axle is a
bit loose - not so much so that I can be certain there's something
horribly wrong with it, but it does have to be checked.

So I have to get the cranks off. And I have just wrecked a brand new
crank tool trying. I _think_ the bottom bracket is square taper but to
be honest can't see enough with the cranks on to be absolutely certain.
It's the relatively modern sort of bottom bracket where the cranks are
held on with allen head bolts which screw into the ends of the bottom
bracket spindle. I have tried the usual tricks - heating the cranks with
a blowtorch, wellying it with a rubber mallet - and absolutely no
movement at all. I don't particularly want to wreck the crankset, but if
I can't sort the problem the bike is scrap anyway.

Suggestions? Wizard wheezes?

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

For office use only. Please do not write or type below this line.

Simon Brooke wrote:
OK, people, let's have your favourite cures for stuck cranks.

Repeated applications of WD40, letting it wait overnight before
attempting removal.

Are you sure you've extracted *all* of each allan bolt? No bit sheared
off the end?

R.

"Simon Brooke" wrote in message
...

So I have to get the cranks off. And I have just wrecked a brand new
crank tool trying. I _think_ the bottom bracket is square taper but to
be honest can't see enough with the cranks on to be absolutely certain.
It's the relatively modern sort of bottom bracket where the cranks are
held on with allen head bolts which screw into the ends of the bottom
bracket spindle. I have tried the usual tricks - heating the cranks with
a blowtorch, wellying it with a rubber mallet - and absolutely no
movement at all. I don't particularly want to wreck the crankset, but if
I can't sort the problem the bike is scrap anyway.

Suggestions? Wizard wheezes?

I've never had joy with hitting or heating. What has worked for me is
building a puller out of bits of metal and bolts which pulls behind the
crank.

Mine is in nasty mild steel, so has a tendancy to bend, so there's an old
crank providing support on the outside. So far it's worked before the bits
behind have bent sufficiently far to be unusable.

Interesting that you wrecked the crank tool rather than the crank though...

cheers,
clive

Simon Brooke wrote:
OK, people, let's have your favourite cures for stuck cranks. I am faced
with a Halfords Carrera hardtail. It has a horrible irregular noise from
the bottom bracket when pedalling - so horrible that I first suspected a
cracked frame, but I can't find any cracks. The bottom bracket axle is a
bit loose - not so much so that I can be certain there's something
horribly wrong with it, but it does have to be checked.

So I have to get the cranks off. And I have just wrecked a brand new
crank tool trying. I _think_ the bottom bracket is square taper but to
be honest can't see enough with the cranks on to be absolutely certain.
It's the relatively modern sort of bottom bracket where the cranks are
held on with allen head bolts which screw into the ends of the bottom
bracket spindle. I have tried the usual tricks - heating the cranks with
a blowtorch, wellying it with a rubber mallet - and absolutely no
movement at all. I don't particularly want to wreck the crankset, but if
I can't sort the problem the bike is scrap anyway.

So you have taken the bolts out and trashed a crank tool? surely you
would have stripped the crank threads first? in which case they are
toast - gas axe time.

A ball joint extractor may be a useful thing for this.. couple of
prongs to go under the crank and a screw thread to push the joint
apart. Failing that the other sort which look like a bolster chisel
with a cutout could be used. And if that fails, use a cold chisel to
split the crank.

Other option.. lay bike on side. Pour coca cola into the crank. Leave a
day and then try again.

Other option 2. Leave the bolt out. Take it for a spin in the hills.

...d

As someone has already posted, if you've removed the allen bolts
already from the cranks and then broken a crank tool, you may have
already knackered the crank threads beyond all hope.

If you can't get an allen bolt out, is it possible you're winding the
wrong way? Doesn't one (the none-drive side bolt, I think) thread the
opposite way?

Nick

Simon Brooke wrote:

I have tried the usual tricks - heating the cranks with
a blowtorch, wellying it with a rubber mallet - and absolutely no
movement at all. I don't particularly want to wreck the crankset,
but if I can't sort the problem the bike is scrap anyway.

Suggestions? Wizard wheezes?

Have you tried saying "bugger"?

Method 1. If you've got a motor car type hub puller or gear extractor
in your took kit you may be able to use that, possibly with a bit of
ingenuity required in getting it to grip behind the crank.

Method 2. Put crank in bench vice and use a punch to knock the spindle,
and the rest of the bike, out of the crank. The alternative of grasping
the frame firmly with both hands, placing the soles of the feet through
the frame and onto the bench either side of the vice and heaving like a
looney may appear tempting, but even with mattresses on the floor may
lead to serious injury.

Method 3. Leave the allen bolt out and go for a ride. If it's a square
taper it should work loose, without injuring you hopefully, otherwise
it probably won't. If you do manage to work the crank loose this way,
it's toast even if it looks undamaged.

Method 4. Failing all of the above, I think you might have to saw the
crank off. Sawing through the crank will be much easier than through
the BB spindle. If you cut a big slot towards the spindle you should be
able to split the crank with a cold chisel.

--
Dave...

NickD wrote:

If you can't get an allen bolt out, is it possible you're winding
the wrong way? Doesn't one (the none-drive side bolt, I think)
thread the opposite way?

No.

--
Dave...

I wrote:

If you've got a motor car type hub puller or gear extractor
in your took kit you may be able to use that...

That was meant to be /tool/ kit of course, though if you've acquired
some of your favourite tools by the tradional method took kit may well
be appropriate.

--
Dave...

David Martin wrote:

So you have taken the bolts out and trashed a crank tool? surely you
would have stripped the crank threads first? in which case they are
toast - gas axe time.


I've done this as well. Very corroded on crank on old bike, not very clean threads.

Result : one buggered crank tool and one buggered crank.

If it was me I'd just get a hacksaw and remove the cranks with that.

Arthur

--
Arthur Clune PGP/GPG Key: http://www.clune.org/pubkey.txt
The struggle of people against power is the struggle
of memory against forgetting - Milan Kundera

"Simon Brooke" wrote in message
...

Suggestions? Wizard wheezes?

Oh yes - forgot another one I've done successfully. Cut the BB axle (I used
an angle grinder, but this probably only works on non-drive side).

cheers,
clive