Which spec of Thread Lock should I use?

dirkpitt74

Guys,
Have noticed that the LHS crank arm bolts are working loose.
Don't have a torque wrench at the moment so can't set correct torque - should be getting one this weekk

Thinking about putting Thread Lock on when I go round re-torquing all bolts.

Is this a good idea? If so what strength/spec thread lock should I be using?

Thanks

miceden

You only need a medium strength thread locker so Loctite 242 Blue Threadlocker... but you probably don't need it on every single bolt.

Chunkers1980

Rotor and jockey bolts are the only places I'd bother to use it.

dirkpitt74

Thanks guys.
Wasn't thinking every single bolt - will probably do crank arm, rotors and jockeys.

This looks to be a similar strength to 242 but in a stick:

Loctite 248 Stick

Might be handy as it shouldn't dry out too much in the tool box.

miceden

The liquid 242 doesn't dry up quickly, I've got a 2yr old bottle still going strong!

veronese68

miceden wrote:

The liquid 242 doesn't dry up quickly, I've got a 2yr old bottle still going strong!

Mines quite a bit older than that. I believe it is made to go off in the absence of air, so doesn't really go off in the bottle.

cycleclinic

My worry is why the crank bolt is working loose. These (if it is a traditional crank bolt) are done up to 40Nm and should come undone by itself. One that does indicates another problem which should be rectified, i.e do it up tighter rather than using loctite and make removal harder.

dirkpitt74

thecycleclinic wrote:

My worry is why the crank bolt is working loose. These (if it is a traditional crank bolt) are done up to 40Nm and should come undone by itself. One that does indicates another problem which should be rectified, i.e do it up tighter rather than using loctite and make removal harder.

Non drive side on FSA Gamma the crank arm pinch bolts are only 11 - 15Nm.
To be fair I hadn't checked them since I got the bike.

Siarm

I use Loctite 243 myself, is good stuff.

Terrytibbs

DirkPitt74 wrote:

thecycleclinic wrote:

My worry is why the crank bolt is working loose. These (if it is a traditional crank bolt) are done up to 40Nm and should come undone by itself. One that does indicates another problem which should be rectified, i.e do it up tighter rather than using loctite and make removal harder.

Non drive side on FSA Gamma the crank arm pinch bolts are only 11 - 15Nm.
To be fair I hadn't checked them since I got the bike.

They shouldn't come loose quickly and don't need thread lock. Firstly, do you have the bearing preload bolt, the one that screws in the axle. If that's been tightened on correctly and then the cranks tightened on to the correct torque, 14.7NM max on these cranks (I'd do it to that) then they shouldn't come off, so I presume there's another fault here.

I'd have a good look at the axle for a crack along the length of the spline it as this could be stopping the crank arm from tightening up properly. (I've seen this before)

Secondly check for cracks and wear on the crank arm.