Campag crankarm securing bolt keeps losening, why?

jhop

I am experiencing problems with a new Campag Centaur triple Chainset which I am running with a new Centaur traditional square taper BB on my winter commuter.

I have never had any problems with Centaur, Record, Chorus or Veloce cranks which I have run or still run on various bikes BUT I am at a loss to explain why despite careful and correct torque tightening the leftside, non chainwheel crank arm, repeatedly and quickly works itself free. No problems at all on the chainwheel side.

I presume the use of some kind of thread locking substance will solve my problem but why is it occuring and have others encountered this phenomenon?

jpembroke

Is the thread partially stripped or crossed?

Smokin Joe

Try moving the cranks one position round on the tapers, that sometimes cures it.

Garybee

It is sometimes worth changing the crank bolts as the threads can get a bit stretched and cause this to happen. Also, have a look at the section of the crank arm that fits onto the BB square taper. Look closely at the area opposite the crank arm (the rounded end of the arm) for any hairline cracks. They often crack here which would allow it to come lose.

jhop

Thanks for the suggestions, I'll check them out and report back.