Loctite, the use of

Hey there,
had a look at the park tools website (thanks for that tip by the way - brilliant)

One thing i don't think it made clear was - when using loctite do you use
it instead of grease, with grease, or on seperate parts of the thread?
(Yes i really am that ignorant)

The photos of it seem to just have a smear of loctite in the middle..

helpa brother (with an italian bb) out would ya?

instead of on the threads but if it is a non sealed b.b you will still need grease on the ball bearings

Personally, i'd just tighten the left side A LOT and lay off loctite. I used to ride an italian bike with that bb issue, it came undone once, tightened it up real hard and it was fine ...

it's the rhs that should have a l.h thread.

...huh? what do you mean? its the left cup that comes undone thru pedalling yeah?

Don't know about that but on an iso b.b the l.h cup has a r.g thread and on the l.h cup a left hand thread where as itialian have r.h thread on both sides, it may be that you end up with almost a double precession ( http://www.sheldonbrown.com/gloss_p.html#precession ) or something why the italians use this bottom bracket god only knows. Your the Engineer lpg I am the mathemtician (who does engineering).

Loctite them both I say.

aye if they're both clockwise-threaded, the left will come undone due to precession, the right crank will naturally tighten. loctite might make it hard to come off in the future...careful

As said above, Italian BB cups both tighten clockwise, therefore the drive side should get a good tightening from the pedalling motion. So just locktite the l/s otherwise you'll never get the driveside one out again (unless you want to damage things), and just use plenty of elbow grease for the r/s.

Beaten to it by 37 seconds!

Remember your intuition is wrong it is the drive side that needs to be l.h thread.

ok so "instead of"... i thought as much but was worried about the uncovered/ naked
bits of threads touching each other...
Or does the act of screwing it in spread the loctite around enough?
(Hence the big wadge of goo in the middle, in the photo above?)

if not, isn't there a danger of the cup and braket seizing if i leave
some parts of the thread exposed (sans loctite, sans grease)?

It's the drive side that comes undone on Italian threaded BBs. I know because it happened a few weeks ago on my bike. Basically the bearings go the opposite direction from the axle rotation (ie they go anti-clockwise on the drive side) and this undoes the bearing cup. That's why British threaded BBs use a reverse thread on the drive side (because British engineering rules the waves - the Italians do nicer paint jobs though).

Momentum It's the drive side that comes undone on Italian threaded BBs. I know because it happened a few weeks ago on my bike. Basically the bearings go the opposite direction from the axle rotation (ie they go anti-clockwise on the drive side) and this undoes the bearing cup. That's why British threaded BBs use a reverse thread on the drive side (because British engineering rules the waves - the Italians do nicer paint jobs though).

Momentum to the rescue again!
So how did you sort yours?

1. low strength loctite on the whole cup, no grease at all.
   
2. bit of loctite on the cup, grease onthe rest of it
   
3. bit of loctite on the cup, no grease on the exposed part of the cup
   

loctite is threadlock.

to be used on threads that you don't want to unwind.
ie: drive side bb italian thread.

and disc rotor bolts on mountain bikes

OK - sorry - this is my fault.
i didn't write my original post very clearly.
I am aware what loctite is and which cup to use it on etc etc

But....

do you put it on the whole thread?
or just part of the thread?

and

if it's just part of the thread (as in pic)
do you leave the exposed bit of thread un-greased?

Just a bit of the thread is sufficient. The idea of loctite-ing the threat is that it stops it ever coming undone unintentionally. You still want to be able to unscrew it if you want.

Grease + Loctite on same threads = pointless.

Grease - lubricates.
Loctite - thread locks.

Why would you want to do that?

(Or I may be mistaken and there probably is some really obscure bolt somewhere that needs both...)

sorry to bring up an ancient thread but i need some loctite advice...
Basically i fitted a phill bb a few days ago, and put loctite on the threads as instructed, however i now want to adjust the chainline a little, the loctite will have dryed by now, will adjusting the bb mean i need to remove the cups and re-apply loctite? or will simply adjusting the cups not affect the strength of the loctite.
Cheers

Depends on the loctite used. The usual ones need the old stuff cleaned off and reapplication.

243 which I use on bikes, suitable for smaller fasteners is "oil tolerant"