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Square-taper cranks won't come off. Tricks?



 
 
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  #1  
Old May 22nd 17, 09:43 PM posted to rec.bicycles.tech
Joerg[_2_]
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Default Square-taper cranks won't come off. Tricks?

The BB on my steel-frame bike is knackered and I can't get the cranks
off the square tapers anymore. Afraid I'll strip out the thread of the
puller tool. Various penetrating sprays didn't help.

From the last time the BB was replaced the bike experienced a transport
across the Atlantic on a ship which probably hasn't helped matters.

Any tricks of the trade?

--
Regards, Joerg

http://www.analogconsultants.com/
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  #2  
Old May 22nd 17, 09:53 PM posted to rec.bicycles.tech
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Default Square-taper cranks won't come off. Tricks?

Joerg, I would try a big, thick washer that will go over the crank arm and behind the crank (between the crank and the bottom bracket spindle), and then pull behind the washer with a big-assed hub puller, or maybe even a smaller steering wheel puller.
  #4  
Old May 22nd 17, 11:27 PM posted to rec.bicycles.tech
Joerg[_2_]
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Posts: 6,016
Default Square-taper cranks won't come off. Tricks?

On 2017-05-22 13:43, Joerg wrote:
The BB on my steel-frame bike is knackered and I can't get the cranks
off the square tapers anymore. Afraid I'll strip out the thread of the
puller tool. Various penetrating sprays didn't help.

From the last time the BB was replaced the bike experienced a transport
across the Atlantic on a ship which probably hasn't helped matters.

Any tricks of the trade?


Another question is, how much torque can one safely put on the crank
puller without risking damage?

--
Regards, Joerg

http://www.analogconsultants.com/
  #5  
Old May 22nd 17, 11:37 PM posted to rec.bicycles.tech
Doug Landau
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Posts: 1,424
Default Square-taper cranks won't come off. Tricks?

On Monday, May 22, 2017 at 2:19:40 PM UTC-7, Joerg wrote:
On 2017-05-22 13:53, wrote:
Joerg, I would try a big, thick washer that will go over the crank
arm and behind the crank (between the crank and the bottom bracket
spindle), and then pull behind the washer with a big-assed hub
puller, or maybe even a smaller steering wheel puller.


I tried something similar before with a big puller and it stripped its
thread.

--
Regards, Joerg

http://www.analogconsultants.com/


Wha?!?! The threads on the big puller stripped? Did it come from Harbor Freight? Sounds like it needed replacing anyway.

In any case, or if you cannot make a steering wheel or pitman arm or other puller work, why the pullers why not simply grind a slot in the crank and pry the slot open-

Better yet just turn the bike upside down, and hacksaw the square taper off.

  #6  
Old May 23rd 17, 01:25 AM posted to rec.bicycles.tech
David Scheidt
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Posts: 1,346
Default Square-taper cranks won't come off. Tricks?

Joerg wrote:
:The BB on my steel-frame bike is knackered and I can't get the cranks
ff the square tapers anymore. Afraid I'll strip out the thread of the
uller tool. Various penetrating sprays didn't help.

: From the last time the BB was replaced the bike experienced a transport
:across the Atlantic on a ship which probably hasn't helped matters.

:Any tricks of the trade?

spacers between the bottom bracket and crank, if required, and a set
of jacobs chuck removal wedges. like:
https://www.amazon.com/Wedge-Sets-Se.../dp/B0067BSG9S
I don't know if that's the correct size to fit around a square taper
spindle.

--
sig 71
  #7  
Old May 23rd 17, 01:56 AM posted to rec.bicycles.tech
Sir Ridesalot
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Posts: 5,270
Default Square-taper cranks won't come off. Tricks?

On Monday, May 22, 2017 at 4:43:21 PM UTC-4, Joerg wrote:
The BB on my steel-frame bike is knackered and I can't get the cranks
off the square tapers anymore. Afraid I'll strip out the thread of the
puller tool. Various penetrating sprays didn't help.

From the last time the BB was replaced the bike experienced a transport
across the Atlantic on a ship which probably hasn't helped matters.

Any tricks of the trade?

--
Regards, Joerg

http://www.analogconsultants.com/


Do you want to reuse that crank?

I've successfully removed very stuborn crankarms by getting two large washers and then cutting a slot in each one large enough to slip it over the BB spindle. Then I simply placed a cold chisel on either side of the spindle and between the washers and vertical. Then it ws just a matter of hitting each of the chisels until the crankarm popped off. It's really good to have the bottom bracket shell supported.

If there's not enough room for the two washers then one washer against the crankarm and the fixed cup is used as the second washer. If the fixed cup is steel there's very little damage to its outside surface.

Good luck and cheers
  #8  
Old May 23rd 17, 04:00 AM posted to rec.bicycles.tech
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Posts: 275
Default Square-taper cranks won't come off. Tricks?

"I tried something similar before with a big puller and it stripped its thread."

That shouldn't happen with a good quality hub puller. In fact, you can remove tapered splined hubs on axles where the nut has been tightened to 350 ft.-lbs. of torque. If the hub doesn't want to come off, you tighten the hub puller as tight as you can and then hit the end of the screw on the puller with a big sledge hammer to break it loose. I've never stripped the threads on any of my hub pullers while doing that.
  #9  
Old May 23rd 17, 04:55 AM posted to rec.bicycles.tech
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Posts: 3,345
Default Square-taper cranks won't come off. Tricks?

On Monday, May 22, 2017 at 1:43:21 PM UTC-7, Joerg wrote:
The BB on my steel-frame bike is knackered and I can't get the cranks
off the square tapers anymore. Afraid I'll strip out the thread of the
puller tool. Various penetrating sprays didn't help.

From the last time the BB was replaced the bike experienced a transport
across the Atlantic on a ship which probably hasn't helped matters.

Any tricks of the trade?

--
Regards, Joerg

http://www.analogconsultants.com/


Yee gods. Try heating the crank up with a propane torch not so hot that you can't touch it. Avoid heating the steel BB shaft. Spray your penetrating oil on it and let it cool and then try again.
  #10  
Old May 23rd 17, 08:23 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 5,697
Default Square-taper cranks won't come off. Tricks?

On Mon, 22 May 2017 13:43:19 -0700, Joerg
wrote:

The BB on my steel-frame bike is knackered and I can't get the cranks
off the square tapers anymore. Afraid I'll strip out the thread of the
puller tool. Various penetrating sprays didn't help.

From the last time the BB was replaced the bike experienced a transport
across the Atlantic on a ship which probably hasn't helped matters.

Any tricks of the trade?


(1) screw the crank puller into the crank all the way, tighten
everything and give the puller a sharp rap with a hammer. I don't mean
a two handed welt intended to drive it through the bottom bracket and
out the other side, just a sharp rap.

Some times a bit of a shock is all it takes.

(2) get everything set and then heat the crank with a hair drier. If
you can get the aluminum crank hot enough so that you can't hold your
finger on it that would be about right. Then a sharp rap and see.

(3) Take the bike to your local bike shop, describe your attempts at
removing the cranks and then say, "Can I pick it up in a week, from
next Monday?".

--
Cheers,

John B.

 




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