Forever loosening crank arm

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Forever loosening crank arm

Postby sil3nt » Thu Jul 25, 2013 3:15 pm

Hi Guy's, My damn left hand side Miche Primato crank arm keeps coming loose on my SingleSpeed. I have re-tightened it a few times now and recently used some Loctite (with more than one day curing time) on the bolt threads and it sill came loose after 3 days of commuting :(

Does anyone have any suggestions here ? I am open to anything at this stage as it's becoming quite annoying.

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by BNA » Thu Jul 25, 2013 3:23 pm

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Re: Forever loosening crank arm

Postby rkelsen » Thu Jul 25, 2013 3:23 pm

Is it the Road or Track version?

If it's the Track version, then you probably need to tighten the bolt more. The torque specification on square taper BBs is quite high (something like 50Nm, IIRC), so you need to go "gorilla" on it.

I have no experience with the Road version. Sorry.
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Re: Forever loosening crank arm

Postby sil3nt » Thu Jul 25, 2013 3:49 pm

Yeah its the track version, I tightened as tight as I can but admittedly this is with a multi-tool where I probably wont have the necessary leverage for 50Nn. Know a good tool for doing this ?
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Re: Forever loosening crank arm

Postby apollocreed » Thu Jul 25, 2013 3:57 pm

Go get a real allen key from the shops and use some flat handle bars as a long extenion to the allen key. Gives you alot more leverage.

Alternatively, buy these:

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OR a torque wrench, if you want to spend the money
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Re: Forever loosening crank arm

Postby rkelsen » Thu Jul 25, 2013 4:01 pm

You won't get it anywhere near tight enough with a multi-tool.

A set like this:
http://www.bunnings.com.au/products_product_kincrome-23-piece-hex-spline-drive-socket-set_P6122315.aspx

Coupled with one of these:
http://www.bunnings.com.au/products_product_kincrome-micrometer-torque-wrench_P6116683.aspx?search=torque&searchType=any&searchSubType=products

Otherwise, any long-handled 3/8" or 1/2" drive ratchet with the set above will do it.

Edit: Beaten to the punch! :)
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Re: Forever loosening crank arm

Postby sil3nt » Thu Jul 25, 2013 4:05 pm

rkelsen wrote:You won't get it anywhere near tight enough with a multi-tool.

A set like this:
http://www.bunnings.com.au/products_product_kincrome-23-piece-hex-spline-drive-socket-set_P6122315.aspx

Coupled with one of these:
http://www.bunnings.com.au/products_product_kincrome-micrometer-torque-wrench_P6116683.aspx?search=torque&searchType=any&searchSubType=products

Otherwise, any long-handled 3/8" or 1/2" drive ratchet with the set above will do it.

Edit: Beaten to the punch! :)


Thanks Kind Sir's you both have been very helpful. I shall make the arduous journey to Bunnings, some 500m from my house and buy something akin to your suggestions.

Cheers
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Re: Forever loosening crank arm

Postby Mulger bill » Thu Jul 25, 2013 8:05 pm

I hate to go all Jeremiah here but I'm wondering if you've ridden her far with the crank loose?
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Re: Forever loosening crank arm

Postby sil3nt » Thu Jul 25, 2013 8:21 pm

Mulger bill wrote:I hate to go all Jeremiah here but I'm wondering if you've ridden her far with the crank loose?


No maybe a couple of hundred meters at max I stopped as soon as I felt some play in my pedal stroke.

I hope I have not done any damage in doing so put see what happens after I give her a really good tighten up.
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Re: Forever loosening crank arm

Postby Mulger bill » Thu Jul 25, 2013 8:46 pm

Sounds good then, riding a loose arm will bork the taper very quickly. Guess how I know :oops:

For a tool, I found an 8mm hex at a crime convergers, hacksawed it in half and took it to work where the lads in the shed welded 400mm of 10mm bar into the middle.
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Re: Forever loosening crank arm

Postby sil3nt » Thu Jul 25, 2013 9:18 pm

Mulger bill wrote:Sounds good then, riding a loose arm will bork the taper very quickly. Guess how I know :oops:

For a tool, I found an 8mm hex at a crime convergers, hacksawed it in half and took it to work where the lads in the shed welded 400mm of 10mm bar into the middle.


Yeah that hurts fingers,crossed:/
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Re: Forever loosening crank arm

Postby foo on patrol » Sun Jul 28, 2013 6:17 am

Mulger bill wrote:I hate to go all Jeremiah here but I'm wondering if you've ridden her far with the crank loose?


My son did this with my MB, only trouble was, he road around for a couple of days with it like this and flogged out the arm. :evil:

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Re: Forever loosening crank arm

Postby Yankers » Sat Aug 03, 2013 12:13 am

In my experience with square taper cranks, once you get any distortion inside the barrel of the crank arm you can never get it to hold thereafter. Really important to stop riding the bike as soon as you feel any play first time round. Always seems to be the left crank arm too - not sure why, perhaps a lateral load sort of issue??
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Re: Forever loosening crank arm

Postby PANZR » Sat Aug 03, 2013 9:36 pm

Is the crankset ISO or JIS square taper? (Miche are often ISO)
Are you using an ISO or JIS taper BB?
If they're not matched, this could be the reason even though you say it's only occuring on one side

For example; if an ISO taper crank is forced onto a JIS taper BB too much it can negatively affect the taper surface of the cranks, causing it to become loose over time
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Re: Forever loosening crank arm

Postby Croweater » Sun Aug 11, 2013 9:05 am

rkelsen wrote:You won't get it anywhere near tight enough with a multi-tool.

A set like this:
http://www.bunnings.com.au/products_product_kincrome-23-piece-hex-spline-drive-socket-set_P6122315.aspx

Coupled with one of these:
http://www.bunnings.com.au/products_product_kincrome-micrometer-torque-wrench_P6116683.aspx?search=torque&searchType=any&searchSubType=products

Otherwise, any long-handled 3/8" or 1/2" drive ratchet with the set above will do it.

Edit: Beaten to the punch! :)


Hey mate,

My Dura Ace 7900 crankset just came loose. I coasted down hill back home but didn't pedal at all.

I'm shitting myself, I hope I haven't stuffed it up! My LBS is closed as it's a Sunday, but need re-assurance I haven't buggered anything! Haha.
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Re: Forever loosening crank arm

Postby rkelsen » Sun Aug 11, 2013 9:32 am

In all honesty, I don't know anything about current road cranksets, aside from the fact that they're a completely different design. Sorry.

Don't use any of the advice above on yours. Wait until an LBS can look at it.
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Re: Forever loosening crank arm

Postby Mulger bill » Sun Aug 11, 2013 3:04 pm

Croweater wrote:
rkelsen wrote:You won't get it anywhere near tight enough with a multi-tool.

A set like this:
http://www.bunnings.com.au/products_product_kincrome-23-piece-hex-spline-drive-socket-set_P6122315.aspx

Coupled with one of these:
http://www.bunnings.com.au/products_product_kincrome-micrometer-torque-wrench_P6116683.aspx?search=torque&searchType=any&searchSubType=products

Otherwise, any long-handled 3/8" or 1/2" drive ratchet with the set above will do it.

Edit: Beaten to the punch! :)


Hey mate,

My Dura Ace 7900 crankset just came loose. I coasted down hill back home but didn't pedal at all.

I'm shitting myself, I hope I haven't stuffed it up! My LBS is closed as it's a Sunday, but need re-assurance I haven't buggered anything! Haha.


What tools do you have/can borrow? No biggie.
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Re: Forever loosening crank arm

Postby Yankers » Sun Aug 11, 2013 4:11 pm

Croweater wrote:
rkelsen wrote:You won't get it anywhere near tight enough with a multi-tool.

A set like this:
http://www.bunnings.com.au/products_product_kincrome-23-piece-hex-spline-drive-socket-set_P6122315.aspx

Coupled with one of these:
http://www.bunnings.com.au/products_product_kincrome-micrometer-torque-wrench_P6116683.aspx?search=torque&searchType=any&searchSubType=products

Otherwise, any long-handled 3/8" or 1/2" drive ratchet with the set above will do it.

Edit: Beaten to the punch! :)


Hey mate,

My Dura Ace 7900 crankset just came loose. I coasted down hill back home but didn't pedal at all.

I'm shitting myself, I hope I haven't stuffed it up! My LBS is closed as it's a Sunday, but need re-assurance I haven't buggered anything! Haha.

You'll be right - definitely did the right thing by not pedaling anymore - that's where the damage gets done.
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Re: Forever loosening crank arm

Postby ColinOldnCranky » Sun Aug 11, 2013 5:54 pm

sil3nt wrote:
Mulger bill wrote:I hate to go all Jeremiah here but I'm wondering if you've ridden her far with the crank loose?


No maybe a couple of hundred meters at max I stopped as soon as I felt some play in my pedal stroke.

I hope I have not done any damage in doing so put see what happens after I give her a really good tighten up.

From experience that is indeed what caused your problem. And, in my experience, it doesn't have to be ridden while loose very far at all to do the damage. Further, again in my experience, you can tighten it up as hard as you like and used loktite and it will still keep on loosening )a Yankers indicated).

I had to carry a socket set around for a month while I found a matching replacement. The crank would require tightening with every trip.

So my advice would be try what you can but don;t waste too much time or too much money in doing so. I expect that you only have one option.

My experience however is on a square taper crank and with no hardened square female that is separate from the body of the crank.
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