Crank bolt keeps comming loose..

[hsvls1255]

hey guys...

i have a specialized roubaix comp (2006) with the FSA sl/k cranks.

for some reason the bolt 9 or whatever the technical name for it) that holds it to the bottom bracket keeps comming loose. when i first had the bike afrew weeks after getting it the bolt loosend up.

After i took it for a service the a few rides later, it loosend up again.... tightend and it has happened again. Is these some fundemental problem with my crank for it to keep comming loose? i tighten the **** out of it, and it keeps comming loose ( after about 2-300kms)..

should i use some locktite on it maybe? anyone else had similar problems??

 

[marvin3784]

Are you using a torque wrench or just a regular wrench? That extra leverage will give you more pressure. That should keep it on. If you don't have a torque wrench, you can put a pipe around your regular wrench. This "cheater pipe" will have a similar action.

 

[kdelong]

Use a torque wrench and tighten the crank bolt to the specified torque. If it still loosens, get a replacement bolt. Every now and then a bolt escapes the factory that has an undersized thread and that could be what is causing the problem. If not, then you may have a slightly oversized hole in your BB. Either of these problems should be warranty issues if you feel like making a fuss over it.

I would advise that you not use locktite on this particular bolt because it would be a real bear the next time that you wanted to remove it, and they are usually hard enough to remove as it is.

 

[Cycler6n]

I heard of another case of this from a rider I saw on the side of the road, same bike too. Yu wouldn't to be that same guy? You live in new york state?

 

[sideshow_bob]

I would advise that you not use locktite on this particular bolt because it would be a real bear the next time that you wanted to remove it, and they are usually hard enough to remove as it is.

apparently it's a bit of a known issue on the fsa cranks. later versions of the cranks came (from fsa) with some brown liquid which is to be applied at the spline/crank interface.

the liquid in the documentation is called a type of 'loctite' however if anyone knows the number i'd like to know (for my own fsa cranks). anyway i've only ever assembled the cranks with the loctite and i've not had issues with the crank loosening. ymmv

also when the bolt is loosening is the self extracting cap also working loose, or is staying in place and the crank arm itself loosening?

--brett