Bicycle Mechanics - Yet another bottom bracket thread

I've decided to treat one of my old bikes to a new bottom bracket. As most of my experience is with the old type bb's, I have a question concerning the newer cartridge type.

I understand they sometimes loosen while riding.

What is the best method of locking the adapter in place? I have heard of people using plumber's tape or even Loctite® on the threads.
To me, Locktite® sounds like overkill. I DO want to be able to remove the bb sometime in the future.

Any suggestions will be appreciated.

Louis

A few years ago Shimano was recommending silicon seal and it worked well. Locktite makes several solutions with different "holding power" some of which are designed to be "broken loose" others for applications where periodic adjustment is needed. Plumbers tape should work as well.

Ride Quiet
Pat

Pat's right. I believe the blue Loctite is "removable" and the red is "permanent". But READ THE PACKAGES TO MAKE SURE. Even the "permanent" stuff can be broken loose, but it's hard. Whatever you use, don't slather it on. Just a couple of drops on the last few threads should do and makes for easier removal and cleanup when the time comes.
Regards,
Raymond

Simply put, the best method of locking any threaded item in place is to tighten it enough. When any part comes loose, it is almost always the case that it was never tight to begin with. For bottom brackets (either cartridge or adjustable type), secure to at least 360 inch-pounds torque. This creates tension in the thread, and that is what keeps it from loosening.

Thread lockers such as Loctite can be useful. They form a seal the acts to keep out water. Use a milder grade, such as the #242. This is rated "service removable", meaning normal service tools can get it apart. Mild heat can also help soften the compound, if that is needed.

It is best to treat the threads before tightening. Using grease or anti-seize means your torque is going to create tension in the threads. A dry thread does not pull as tight.

I am not a big fan of "plumber's tape". It is intended for form either a watertight or airtight seal in the very course and tapered pipe threads. If it is all you have, certainly use it, but grease, anti-seize, or a mild thread locker are a better choice.

For more on bottom bracket installation see http://www.parktool.com/repair_help/FAQcartdg.shtml

Would that best be done using a torque wrench? ;)

FWIW, most Shimano BB's come with some stuff already on the threads. The stuff is grey in colour, so I'm not sure just what it is, but I've been told by mechanics that it is suggested that this stuff will prevent loosening of the cups.

Thanks everyone for the information.

I'm glad to have your opinions on the Loctite. Although I won't use it here, it's good to know these things. I was afraid that stuff was permanant.

That Park Tool website is very helpful, and interesting as well.

My new bb arrived today and when I took it out of the box the first thing I noticed was, it does have a grey/white substance painted on the threads just as Alex described.

The timing could not have been better. Now I feel sure I'm not going to screw it up.
:)

Again, thanks all. :beer:

Louis

Don't forget the drive side is LH threaded. For BBs, turn toward the back of the bike to tighten and toward the front to loosen. Pedals are the opposite.

Yeah, for some reason, on bb's, I always remember which side is reverse threaded.
But pedals, I always have to stop and think. Can't explain why. :confused:

Thanks

Louis

In the years I have never had one come loose.

If this is a concern you may want to try either teflon tape or the specific Loctite reccomended.

Do not worry. Make the change.

Since the grey colored stuff that Shimano has applied to the threads is evidently meant to lock the whole thing in place, I'm going to stick (pun intended) with that and see what happens.

If needed, I can spring into action with Plan B.

Interesting that your bb's have stayed tight. Hmmm...maybe I worry too much.
:)

Thanks

Louis

Another thing about cartridge bottom brackets--the rings are separate from direct contact with rolling ball bearings and so can't be mechanically influenced to loosen as cup-and-spindle bb's could. They should still be installed to manufacturers' torque spec. On aluminum or ti bottom bracket shells, anti-sieze is a better idea on the threads than loctite as keeping the cartridge in usually isn't half the problem of getting it back out when you need to. On aluminum bb rings into an aluminum shell, I'd call anti-sieze an absolute necessity.