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Strange crank arm nuts - removal

Old 09-04-16, 10:02 PM
  #1  
zoom996
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Strange crank arm nuts - removal

https://i.imgur.com/r8nB9mn.jpg

https://i.imgur.com/IoPi70H.jpg

I'm trying to remove these nuts. A 6mm hex fits snugly but one side is rounding a little. I tried spraying penetrant on it but still stuck. There is nothing special to removing these right? Just regular right hand threads?
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Old 09-04-16, 10:11 PM
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Yes, very strange nuts. So strange they're called bolts. Nice and rusty. (Remove the self-extractor rings to have a chance of removing the bolts.)
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Old 09-04-16, 10:34 PM
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Also known as "One Key release". These are Shimano's first attempt at self-extracting crank bolts. I agree with the Ankle: remove the retaining ring with a pin spanner, then use a good quality, tight fitting hex key on a socket handle to break them loose. Remove them and replace them with standard bolts torqued to 30 ft-lbs.

Throw away the One-Key Release bolts. Unless they're torqued carefully, it's very hard to get the correct amount of torque with a 6mm hex key. Back when they came out, I saw many Shimano cranks ruined due to inadequate torque.

Here's what they look like new:

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Old 09-04-16, 10:39 PM
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Anklework: Don't be a smart ass. If you want to help, tell me the correct term without the extra attitude. What's the correct term for this style of bolt?
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Old 09-04-16, 10:41 PM
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Thanks Jeff. I'll throw them away.
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Old 09-04-16, 10:50 PM
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Originally Posted by zoom996 View Post
What's the correct term for this style of bolt?
"Socket head cap screw": https://www.grainger.com/category/so...ecatalog/N-8n7
but that won't get you anywhere at a bike shop. These were special for Shimano, and only, ummm, "experienced" mechanics will know about what trouble they were back in the '80's. The current versions use an 8mm hex key, but a torque wrench is still needed. 30 ft. lbs. is a lot of force to apply with an ordinary hex key (aka "Allen wrench").
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Old 09-04-16, 11:18 PM
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Just for your information, the reason these bolts are hard to remove is because they're also removing the cranks at the same time. It's quite hard to turn tool to remove square taper cranks, so I'd say if you're rounding off the bolt then remove the ring. Good luck, working with a pin spanner sucks.
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Old 09-04-16, 11:23 PM
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Originally Posted by corrado33 View Post
Just for your information, the reason these bolts are hard to remove is because they're also removing the cranks at the same time. It's quite hard to turn tool to remove square taper cranks, so I'd say if you're rounding off the bolt then remove the ring. Good luck, working with a pin spanner sucks.
Whups- I agree. I got ahead of myself.

If you can unscrew the bolt one or two turns then it gets tight again, it's doing what it's designed to do: remove the crankarm. I still say that 6mm is too small a hex to correctly torque the crankarm, either tightening or loosening. Conventional 14mm bolts work much better, but you need the "normal" crankarm removal tool to take them off afterward.
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Old 09-04-16, 11:57 PM
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Originally Posted by zoom996 View Post
Anklework: Don't be a smart ass. If you want to help, tell me the correct term without the extra attitude. What's the correct term for this style of bolt?
I thought I wrote "bolt" and what you needed to know. You're welcome.
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Old 09-05-16, 05:33 AM
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your mind works faster than your typing and gets ahead
the people who call it out? well...
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Old 09-05-16, 06:02 AM
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Actually, Shimano used 8 mm hex keys for their one-key release cranks. Suguino and a couple of aftermarket makers used 6 mm hex keys and, I agree, 6 mm isn't big enough.
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Old 09-05-16, 05:52 PM
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Originally Posted by HillRider View Post
Actually, Shimano used 8 mm hex keys for their one-key release cranks. Sugino and a couple of aftermarket makers used 6 mm hex keys and, I agree, 6 mm isn't big enough.
First series Shimano One-Key Release used a 6mm.

(1982 Shimano catalog, courtesy Sheldon Brown)
1982 Shimano Catalogue Page 08

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Old 09-05-16, 06:56 PM
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Originally Posted by Jeff Wills View Post
First series Shimano One-Key Release used a 6mm.
I unthread corrected. However, Shimano realized their mistake by the time 7700/6500-series cranks came along.

I had a set of the Suguino "Autex" crank bolts on an old square taper crank and always thought their 6 mm sockets were marginal for that service.
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Old 09-05-16, 07:14 PM
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If you have it, a hex bit in a low-torque impact gun is probably your only hope if you can't get the retaining ring off. I like to use a hex bit in a torque wrench to assemble.
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Old 09-05-16, 10:27 PM
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Yea the spindle bolt is Lefty -Loosie BUT


I have had A Negative 'self extracting , experience'

where the un screwing of the Bolt simply stripped 0ut the threads ,

Never budging the crank arm .....



A) remove the pin spanner ring .

then unscrew the bolt ..... then use a regular extractor ... It engages All the threads in the arm...


the extractor ring has many fewer threads engaged...
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Old 09-05-16, 11:44 PM
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Thanks for the info. I tried removing the ring and I broke my pin spanner. I bent two 6mm wrenches trying to release the crank arm. One side eventually came off but the other side is still stuck and almost stripped.

I need to replace my pins and buy a new hex wrench before I try again. Does anyone know of a super hardened 6mm hex wrench I could buy and try?
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Old 09-06-16, 09:06 AM
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Originally Posted by zoom996 View Post
Thanks for the info. I tried removing the ring and I broke my pin spanner. I bent two 6mm wrenches trying to release the crank arm. One side eventually came off but the other side is still stuck and almost stripped.

I need to replace my pins and buy a new hex wrench before I try again. Does anyone know of a super hardened 6mm hex wrench I could buy and try?
Bits for impact guns are usually harder. Don't use a wrench. Get a bit and use it on a ratchet.
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Old 09-06-16, 09:23 AM
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Originally Posted by zoom996 View Post
Thanks for the info. I tried removing the ring and I broke my pin spanner. I bent two 6mm wrenches trying to release the crank arm. One side eventually came off but the other side is still stuck and almost stripped.
Try snugging up the bolt first which takes the pressure off the pin-holed extracter ring making it easier to remove. If you get them off, as others have mentioned, you may be able to get the bolts out easier and then, also as others have mentioned, use a proper crank extractor tool to remove the arms.
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Old 09-06-16, 09:57 AM
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If this were me, and it was a crank I absolutely wanted to save, I'd take a socket that has the same diameter as the pin holes, then I'd grind the socket away until 2 "pins" were left. I'd put the socket on an impact wrench and, with the bike BB sitting against something solid, lean on the impact wrench and remove the rings.

Luckily, you have two chances at removing this crank. First I'd try an impact with a 6mm allen. If that strips, usually allen socket cap screws strip in one direction, you you should be able to tighten the allen again (taking the pressure off of the extractor ring.) Then I'd make the socket thing I mentioned above and try again. Once you get the extractor ring out the allen should come out easily since you already loosened it.

If all else fails, hammer a torx bit into the allen and use an impact with that. If that fails, hit the extractor ring till it breaks. (Alternatively, cut it off with a dremel.)

Those bolt "removal" tools aren't meant to remove a STUCK bolt, they're meant to remove a looseish STRIPPED bolt.

Last edited by corrado33; 09-06-16 at 10:04 AM.
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