Hi everybody

I have a sealed bottom bracket (Shimano Ultegra: https://www.jensonusa.com/store/produ...m+Bracket.aspx)

and I'm having problems threading into onto a new caad9 frame (https://i38.photobucket.com/albums/e1...pboard01-3.jpg).

The left-side (non-drive) threaded on fine, but the drive side threads wouldn't watch; it just kept turning. I tried putting left side in first, and right side first. I didn't mess up the side each cup goes on, and was turning them the right way.

Anyone have any ideas?

No specific advice, but most importantly, don't get frustrated and do something you will regret. Don't be insulted by this advice, it is REALLY easy to rush it a tad and essentially ruin the frame. Be slow and walk away for the day if nothing is working.

Okay, here is some specific advice. We are more used to using threads on smaller diameter things like bolts. Large diameter threads are far more sensitive to angle of entry. I have had good luck by turning the cup the wrong way very slowly and carefully and gently until you can feel (like a safe picker) the end of the thread on the cup click over the end of the thread on the shell. When you feel this, gently reverse direction to the correct way and hopefully the threads will mate.

Patience grasshopper,

jim

My idea was to make sure you were turning right side counter clockwise but then I got to the end of your post. I have occasionally had trouble getting BB cups to catch threads. It invariably was a matter of getting threads lined up right as the other poster noted. If cup won't catch initially, I just pull it out rotate cup a bit, re-engage, pull cup out, rotate slightly, re-engage, pull cup out, throw cup across the garage, have a beer, go to bed, come back tomorrow, rotate cup a bit, re-engage. I get there eventually.

You know the drive side is left hand threaded?

yea i got the left side in fine. it was no trouble

If this was response to CO Steve post about drive side being left handed threaded, it would seem perhaps you are not turning drive side (right side) correct way as your installation of left side is not relevant to CO Steve comment. The left side is right hand threaded (clockwise -- righty tighty), right side (drive side) is left hand threaded (counterclockwise). Another way to think about it, regardless of which side you are working, tighten the cup by turning toward the rear dropouts.

Here's my trick for matching up fine pitch threads. Turning the cup by hand, rotate it the wrong way slowly. At some point during the rotation you will feel the cup drop into the shell a little bit. This is the point where the start of the threads on each part have just passed each other. Stop turning the wrong way at that exact point and turn the right way. The cup should thread in easily by hand. I use this method any time I find that a cup isn't threading in as smoothly as I would expect and it's saved me numerous times from crossthreading a cup.

+1
This is exactly what i do.

Also check to make sure the bolt holding the cable guide on the bottom of the shell is not interfering, by backing it out a ways. If your bb has some mystery scratches on the label after install attempts, this is your culprit.

I always forget about that dern bolt and struggle with the BB install until in dawnson me. Then I forget to tighten it and takes me two days of tinkering with cables before I figure out why my derailleurs aren't quite right.