Has the topic been addressed somewhere? Search gets BB drives.
The problem is the BB tube is out of round. Both R & L bearing cones bind. There is no alternative to repair as all these swingarms have this problem.
First observation is the tube is welded, has ridges & different hardness. I'm limited on tools, no retapping or thread chasing; no micrometer to identify oval or round. I removed the highes & its area threads with a dremel tool.
Second is the cup can wobble trying to start its correct threading. This wobble effect is into the weld, so the out of round is 90" opposite of it.
Hours of trying different cups, all want to cross thread, 2 succeeded in following the tube threads. ALL my day wasted figuring this out. The cup threads are fine, checked all with magnifier, cleaning threads with a fine wire brush too.
Get the alignment correct & the cups are a struggle wrenching. The narrow lips designed for special stamped wrenches are very difficult with an adjustable wrench. An opened end 16mm doesn't contact both surfaces on each side of the axle hole, not deep enough.
The cups are supposed to finger tighten, so I need to adjust the threads to fit a flattened hole. I done so on the left handed cup as it is not the adjustable side. I removed MOST of the thread from the tube, but not all. The cup fit in LOOSELY. So the observation is threads are not undersized, as in cut deep enough in the tube to not bind. The left stationary cup is now permanently seated with glue.
The opposite side needs to adjust, grind & glue isn't a solution. Has anyone else done this? Get a loose enough fit to adjust the cup without stripping? I'm getting an idea, find the indent of the oval first.
Back with that observation. Time for real glasses too, instead of dollar store "magnifiers".