Crank pinion nut

[Tigger52]

Hi all,

Twice now I've had the crank pinion nut come loose and lock up the motor as it alllows the crank to move sideways - towards the flywheel!

It's been torqued to the recommended 40lbs but it's just come loose again and ruined another days riding.

Am I missing something, should there be a lock washer of some sort behind the nut to stop this happening?

Suggestions very welcome as this is really p***ing me off now.

Many thanks

 

[GMP]

40 ft/lbs? The spec is 98 Nm or 72 ft/lbs. Clean threads of oil real well, and use loctite, torque to spec. Let loctite cure before filling trans with oil.

 

[Tigger52]

Thanks Glenn,

That's a help.

What Loctite should I use to make sure it never comes loose again?

Simon

 

[GMP]

I just use the blue Loctite, I forget the number but its the low/med strength stuff. If the nut is tightened to spec its not even neccessary, but it won't hurt.

FYI, whenever you use Loctite on an internal fastener like this that sees oil, its important to let it cure fully before filling and use. This is what hurt Cannondale bad in '03. To meet production goals they filled engines too soon, and the Loctite failed on the transmission cassette bolts, causing major problems.