How do you get off a crank with a stripped thread?

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bigjim
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Re: How do you get off a crank with a stripped thread?

Postby bigjim » 2 Mar 2009, 3:27pm

Nonsense.

C3. Don't be so rude! Who brought you up? I was only repeating what the LBS said to me and the word was evidently. I don't know I am not an engineer and don't realy care that much. I have 30yr old bikes without this problem but that does not prove anything. Got a 90yr old granny smokes 40 a day. Does that mean smoking is good for you?
Nothing left to prove.

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CJ
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Re: How do you get off a crank with a stripped thread?

Postby CJ » 2 Mar 2009, 4:49pm

Sorry Bigjim. I didn't mean to be rude, just brief. I should have put "what you were told is nonsense".

Please accept my apologies. :oops:
Chris Juden
One lady owner, never raced or jumped.

LANDSURFER74

Re: How do you get off a crank with a stripped thread?

Postby LANDSURFER74 » 6 Nov 2010, 9:29pm

Disimilar metal corrosion has been with us for ever;
As previously stated , apply heat and shock even with a 'new' crank arm.
Install extractor , apply torque, heat, shock ( that's hit the extractor with a 4oz hammer, for all those working in the banking industry) , never rely on the extractor removing the crank arm with out a little help, it may well , but if not ....you've had it.

and all you 'hard' engineers out there ..yes a 4oz hammer is all it takes.

spanner
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Re: How do you get off a crank with a stripped thread?

Postby spanner » 9 Apr 2011, 3:16pm

LANDSURFER74 wrote:Disimilar metal corrosion has been with us for ever;
As previously stated , apply heat and shock even with a 'new' crank arm.
Install extractor , apply torque, heat, shock ( that's hit the extractor with a 4oz hammer, for all those working in the banking industry) , never rely on the extractor removing the crank arm with out a little help, it may well , but if not ....you've had it.

and all you 'hard' engineers out there ..yes a 4oz hammer is all it takes.

easiest way is a ball joint splitter the one with a v and long handle down the back of the chainwheel and whack the joint splitter with a hammer comes off no bother if the thread is stripped as the chainwheel or crank is scrap
if the bb axle has a bolt in thread fitting and you can get the left hand crank off take out the bb cup and put a punch that will fit inside the bb axle bolt hole and keep hitting it with a hammer the shock force will take the bb axle out of the chainwheel.
the usual cause of this problem is some prat none mechanic putting grease on the axle flats usually that crap white bike grease which when exposed to the air goes brick hard the flats of the axle should be absolutely clean no grease whatsoever.
ive been lucky a few times using the remove left hand crank and the punch in the bb axle thread hole method thereby saving the threads in the chain wheel cleaned up the axle flats regreased the bb cups and put everything together job done.

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Steve Kish
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Re: How do you get off a crank with a stripped thread?

Postby Steve Kish » 9 Apr 2011, 7:51pm

From my experience, it's not the softening of the aluminium with age that causes this stripping but simply just not threading in the extractor far enough before tightening the pulling bolt. :roll:
Old enough to know better but too young to care.

spanner
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Re: How do you get off a crank with a stripped thread?

Postby spanner » 9 Apr 2011, 8:04pm

Steve Kish wrote:From my experience, it's not the softening of the aluminium with age that causes this stripping but simply just not threading in the extractor far enough before tightening the pulling bolt. :roll:

CONFUCIOUS SAY BIKE MECHANIC WHO FORGETS TO REMOVE WASHER BEHIND BOLT IN BB AXLE LIABLE TO STRIP THREADS IN COTTERLESS CRANK
ie some bb axles which have a screw in bolt instead of a nut some have a shouldered bolt ie a washed inbuilt into the bolt other bikes have a seperate washer if you forget to remove this washer the extractor wont screw in far enough and when you tighten the extractor bolt the extractor will rip out the threads inside the crank

drossall
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Re: How do you get off a crank with a stripped thread?

Postby drossall » 9 Apr 2011, 9:12pm

Another vote for the bearing puller. Mine can be built with two or three arms; it fits some chainsets better one way, and some the other. Didn't cost that much, from Halfords I think, years ago.

PJ520
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Re: How do you get off a crank with a stripped thread?

Postby PJ520 » 11 Apr 2011, 4:37pm

It helps to put a very light smear of Copaslip (or Alumslip is better if you can get it) onto the axle before fitting.


Is Permatex AntiSieze acceptable? I use it on my pedals and they always come off a treat but my LBS guy doesn't like it, says it migrates into the bearings and does harm, which frankly I find hard to believe.
You only live once, which is enough if you do it right. - Mae West

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Mick F
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Re: How do you get off a crank with a stripped thread?

Postby Mick F » 11 Apr 2011, 4:48pm

Remember, the BB and crank manufacturers tell you to assemble dry and clean.

All taper fittings should be assembled dry, that's the way they work. The trick is to remove them from time to time so they don't seize on.

Also, if you think about it, the crank fits the taper EXACTLY and when you tighten the bolt, it fits FIRMLY so there shouldn't be any room for grease! If there is, you haven't got a good solid mating surface.
Mick F. Cornwall

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al_yrpal
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Re: How do you get off a crank with a stripped thread?

Postby al_yrpal » 11 Apr 2011, 5:17pm

Aluminium is a great conductor of heat. Immerse it in a jug of very hot water and then try to tap it off with a hammer with chammy leather over it to prevent damage to the surrounding area.

Failing that, I would protect the surrounding area and split it carefully using a sharp cold chisel after chain drilling a line of small holes in line with the BB through one side so that its perforated.

Al
Touring on a bicycle is a great way to explore and appreciate the countryside and towns you pass through. CTC gone but not forgotten!

spanner
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Re: How do you get off a crank with a stripped thread?

Postby spanner » 31 May 2011, 10:38pm

if the bb axle is the type with the bolt that goes into the axle its possible to shock it off by taking the left hand crank off first then the bb cup and lock ring then using a drift that fits in the hole where the bolt screws in on the chainwheel side and keep whacking it with a heavy hammer and it will come off if it isnt this type ie a sealed unit this isnt an option
as regards the axle this has to be absolutely clean no grease or any type of lube whatsoever ive had occasion to remove cranks to find that the crap white bike grease has been applied to the axle flats and gone brick hard like chalk
only option to get the chainwheel off is a ball joint splitter the long type with a v put it at the back of the chainwheel and whack the splitter with a heavy hammer and it will shock off also remember if the threads for the extractor are stripped the chainwheel is scrap anyway look on ebay as someone may be selling a viscount chainwheel on there

TonyR
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Re: How do you get off a crank with a stripped thread?

Postby TonyR » 1 Jun 2011, 7:25am

Another vote for the single mention above of riding it with the crank bolt loose. It will soon come loose but stop riding as soon as that happens as riding a loose crank can damage the taper in it.

pete75
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Re: How do you get off a crank with a stripped thread?

Postby pete75 » 1 Jun 2011, 5:17pm

The crank repair set half way down this pages is perfect for the job but probably costs more than most chainsets...

http://www.cyclus-tools.eu/tretkurbeln.html?&L=3

spanner
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Re: How do you get off a crank with a stripped thread?

Postby spanner » 1 Jun 2011, 8:06pm

Pete Jack wrote:
It helps to put a very light smear of Copaslip (or Alumslip is better if you can get it) onto the axle before fitting.


Is Permatex AntiSieze acceptable? I use it on my pedals and they always come off a treat but my LBS guy doesn't like it, says it migrates into the bearings and does harm, which frankly I find hard to believe.

i use copper grease on the pedal threads of all my bikes and have never had any problem with the pedals in getting them off i also use it on the handlebar stem and seat posts (aluminum) to stop them from seizing in the frame/fork steerer column.

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andrew_s
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Re: How do you get off a crank with a stripped thread?

Postby andrew_s » 12 Jul 2014, 1:47pm

spanner wrote:CONFUCIOUS SAY BIKE MECHANIC WHO FORGETS TO REMOVE WASHER BEHIND BOLT IN BB AXLE LIABLE TO STRIP THREADS IN COTTERLESS CRANK
ie some bb axles which have a screw in bolt instead of a nut some have a shouldered bolt ie a washed inbuilt into the bolt other bikes have a seperate washer if you forget to remove this washer the extractor wont screw in far enough and when you tighten the extractor bolt the extractor will rip out the threads inside the crank

BTDTGTTS
It's not that the extractor won't screw in far enough - it's the extractor screw-in remover stud clamping the washer against the end of the axle that does the damage