Originally Posted by
oneclick
Go backwards - if a right-threaded cup, place it in the shell and turn anti-clockwise with light pressure. When the cup gets to a point it will drop inwards one thread and that's when you know you have the start.
For damaged threads there may be more than one point where the cup drops. Check the cup visually as most often the original threads will still be there, and hopefully they are still deeper and better formed than whatever damage there is. Go around several times and decide which point has the best-feeling drop - size, and at the moment after the drop look at the alignment. Use that.
Originally Posted by
merziac
Yeah, that's the standard working theory for this, not always that straight forward and not for the inexperienced.
Not always, that's where many make their mistake, if the starting threads are only half good after a rework, they can get you in more trouble so caution wins the day.
If you screw this up at the drag strip, you don't make the next round, I never missed a round in 25 years.
Never had to pull a motor or transmission out or apart either for this in 35 years, 25 professionally.
I think I see your point here, certainly you need some experience to get that kind of feeling and precision and to be able to detect anomalies in threads.
I had taste of this today on another campy bb, Italian thread. The lockring engaged in the adjustable cup and just using hands it was stuck as soon as all threads were in. I tried to inspect it having in mind what has been said here, but couldn’t find anything. Another identical lockring from another bb worked just fine, so the problem was not the cup. As I went on with a wrench and did a few back and forth, eventually I was able to tighten by hand up to halfway. However, when I tried the lockring on another adjustable cup, it engaged but stopped after the first thread. This is the kind of situations where I’m still not sure of what happens and what would be acceptable, and where experience matters.
All this to say that yes, you have to practice through different situations to learn. But also that this forum is an exceptional source of knowledge thanks to all of you !!!
