Cleaning BB shell threads ...

177

rBotM Winner
I'm pleased that I have managed to remove the BB from the latest Montello with not too much of a struggle.

Often removing the drive side cup and be a right bastard.

Anyway; one thing I am always really paranoid about with old frames is the threads ...

Do you run a BB tap through to "clean" threads (and risk damage) or do you just clean them out; grease them up and insert the BB???
 
mdvineng":1em54zuy said:
As long as there is no deformation of the existing thread, just clean and lubricate.

That is what I usually do ...

At what point do people re-face the BB?
 
Only in exceptional circumstances, most imperfections from damage caused whilst undoing bb's can be cleaned off using a small file.
 
Re:

A tap wont damage the shell. It will make the threads sharp which prevents damage to the threads.
 
Re:

A nice stiff stainless steel brush (welders brush) dipped in mineral spirits works well to remove all the grit and corrosion in the bottom bracket threads (do not use the stainless brush on aluminum threads, use a very stiff nylon or brass brush), I have always been surprised how much nasty stuff is living in there. Follow with clean rags moistened with mineral spirits and wipe until the rags come out clean. At this point you can inspect the threads and decide whether to chase the threads with the correct bottom bracket tap(s) or if every thing is nice, reassemble. Test fit all the perfectly cleaned threaded components with a drop of oil, if all the threads are clean enough every thing should assemble by hand with little or no effort. if every thing screws all the way home, you are golden, if at any time things feel "gritty" your parts are not clean enough, if things suddenly stop, there are less than perfect threads or grit somewhere, stop back the threaded parts out and look with magnification for thread damage or grit, correct any issues and try again. Doing it this way your threads should last forever.
Some may disagree with this, I coat all the bottom bracket threads with copper anti-seize before assembly and I never have issues at dis-assembly for maintenance. I use Loctite 242 for the adjustment lock ring only.

: Mike :D
 
Montello":mftvjnl6 said:
mdvineng":mftvjnl6 said:
As long as there is no deformation of the existing thread, just clean and lubricate.

That is what I usually do ...

At what point do people re-face the BB?

Most BB threads will simply clean up, if the cup threads in then great. Sometimes the threads become 'dull', less sharp and a cup won't thread in, it will jam. That notmally happens is a old cup was too loose or tight and took force to remove. That is when a BB thread tool will come into its own. It definitely won't damage a thread. It will make an existing damaged thread as good as it will be.

Most BB shells don't require facing. Most BBs, especially sealed units will just work. A BB would need to be faced on older cup and cone BBs if you could never get a smooth bearing feel through 360 degrees. If the BB had a slack spot that you could never remove without introducing a tight spot then the faces were probably out. That is when you face the BB.
 
Cleaned it all out. I can thread the cup in with fingers about 7 half turns then need a tool to insert the cups the rest of the way.

Worth running the tap through or best left alone?
 

Latest posts

Back
Top