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PostPosted: Tue Aug 13, 2013 1:17 pm 
MacRetro rider
MacRetro rider

Joined: Wed Jun 12, 2013 9:02 pm
Posts: 274
Location: Airdrie North Lanarkshire
the left carnk keeps coming loose its a square bottom bracket any ideas if i can fix it or will i have to replace the bb and crankset?


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PostPosted: Tue Aug 13, 2013 2:12 pm 
Retro Guru
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Joined: Sun Mar 14, 2010 2:33 am
Posts: 2917
Location: daaan saaaf
If it's been ridden with it loose, it will deform the shape of the tapered square hole in the crank and it will never tighten properly again and will keep coming loose. It's unlikely to have damaged the spindle of the bottom bracket, it's really hard steel.

Have a good look at the crank, if the tapered square hole looks flared, misshapen or chewed, you'll have to replace it.


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PostPosted: Tue Aug 13, 2013 2:25 pm 
MacRetro rider
MacRetro rider

Joined: Wed Jun 12, 2013 9:02 pm
Posts: 274
Location: Airdrie North Lanarkshire
thanks ive had a look and its a bit misshapen only happened last time i had bike out nearly lost crank about 6 miles up a forest trail got it tightened and it lasted till i got back to the car so its a good excuse to replace it with some xt/xtr bits


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PostPosted: Wed Aug 14, 2013 8:00 pm 
Old School Grand Master
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Joined: Mon Jun 14, 2010 9:06 pm
Posts: 4422
Location: Herts UK
give it one last go with some 2-part epoxy on the spindle/crank and loctitie on the bolt.


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PostPosted: Wed Aug 14, 2013 8:49 pm 
MacRetro rider
MacRetro rider

Joined: Wed Jun 12, 2013 9:02 pm
Posts: 274
Location: Airdrie North Lanarkshire
i found someone on ebay that sells the crank for £10 going to get that for just now and save for a better set up


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PostPosted: Thu Aug 15, 2013 2:43 am 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
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Joined: Sun May 25, 2008 11:03 am
Posts: 18207
Location: Sunny Glasgow
Crank it on but not too tight( dont forget to grease the spindle :wink: ) ,threadlock the bolt in and try that. The threadlock should help to some extent and will almost certainly stop it falling off mid ride but if it does slacken or feel like its moving, then tighten it a bit more and threadlock the bolt back in.

Owning a torque wrench make a difference when fitting things like this, prevents you from inadvertent doing any damage. Basic park ones are about £30 i think :?

DONT FORGET to keep checking the clearance of the arm in relation to the left(non drive) chain stay, last thing you want it to do it come into contact, and on that note be aware there might be some deflection that could cause a left crank arm to hit the stay if youre pushing hard on the right(drive side) :?


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PostPosted: Thu Aug 15, 2013 7:37 am 
Retro Guru
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Joined: Tue Aug 07, 2007 12:22 pm
Posts: 2942
Location: Platsa, Messinias, Greece
This will most likely work, although it sounds a bit bodgy.

A smear of grease on the taper then wrap in two or three layers of aluminium foil with Loctite 641 between the layers and inside the degreased crank arm.
Fit as normal, making sure the crank arm goes over the foil and doesn't scrunch it up. A drop of 263 on the bolt and torque it up. Leave it a few hours and then ride and re-check for tightness.
The foil gets displaced from the areas that are making perfect contact and fills in those that aren't, bonded into place by the 641.


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PostPosted: Thu Aug 15, 2013 9:55 am 
MacRetro rider
MacRetro rider

Joined: Fri Feb 09, 2007 4:16 pm
Posts: 8658
Like that bodge Andy R, might give a new lease of life to an old crankset I have 8)


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PostPosted: Thu Aug 15, 2013 8:48 pm 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
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Joined: Sun May 25, 2008 11:03 am
Posts: 18207
Location: Sunny Glasgow
Andy R wrote:
This will most likely work, although it sounds a bit bodgy.

A smear of grease on the taper then wrap in two or three layers of aluminium foil with Loctite 641 between the layers and inside the degreased crank arm.
Fit as normal, making sure the crank arm goes over the foil and doesn't scrunch it up. A drop of 263 on the bolt and torque it up. Leave it a few hours and then ride and re-check for tightness.
The foil gets displaced from the areas that are making perfect contact and fills in those that aren't, bonded into place by the 641.


I use a similar method for fitting my headsets when theyre just too loose. I have some self adhesive foil shim. I've only a little left now :( you see i found it and after years of use its down to probably enough for one more headset and ill be terribly sad.,loss of an old and trusted friend.
Really cant remember where it came from but as you say it the fitting scrapes off the excess and fills the gaps.


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PostPosted: Thu Aug 15, 2013 9:13 pm 
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Joined: Tue Aug 07, 2007 12:22 pm
Posts: 2942
Location: Platsa, Messinias, Greece
You get self-adhesive foil for sealing stove flue pipes. If you can't get it here I can bring you some back from Greece.


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