Why is my BB cross-threading all on it’s own?!?
- Thread starter bunnyman666
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I had the same problem on a Walmart Beast. The threads weren't that great brand new. It needed grease since it had none when new. It took several tries to get it threaded in correctly. It kept wanting to cross thread. Just keep trying to get it started in the right thread. Then never take it back out again.
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You’re right, and since this bike is, for all intents and purposes, a Walmart beauty, the threads aren’t that crisp. If worse comes to it, it will become a drag racer with a motor. I won’t need a functioning BB when I have a motor on it.
The way I finally got mine to thread was to rotate the cup backwards until I felt it drop off the end of the thread, then ease it back on. It still took a few tries with the threads oiled up. There may be one more way, if the cup will go in from the other side, if there is room in the BB. Then it could be threaded back through to clean up the threads.
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This is going to make me sound like a cork-sniffing snob, but I haven’t worked on bikes of this calibre since the early days of me wrenching. We tended to take stuff like this in trade, if for no other reason, just to get them on something nicer. It seems that caged ball bearings have gotten worse over the years unless you want to spring for something rare and expensive, sadly. Worse yet, these BB threads would have stripped an aluminium BB! Just like mid-level Shimano hubs won’t come without disc brake rotor mounts, you can’t find a nice BB that is caged BB. I get it. The world has moved on.
I literally forced the BB into the frame with nicely greased threads. I have a lock ring to keep it in. This just was a sad day. A bit frustrated, as literally I have built seven bikes with no issue. This one has given me FITS!!!
right or left side?
If it's the right side, a cartridge bb will stay pretty straight as the spacer and bearing part will self center in the shell. use one of those to try to clean up the treads. yah, the occ has a wwwwwiiiiidddddeee shell and axle.
Or take it to a decent bike shop that has a bb tap and have them chase the threads. shouldn't cost $20. the better taps have guides that slide in to each other (left & right) so they are always exactly on the same axis, centered and perpendicular to the shell. Not worth buying but worth paying someone who has a good set. The cheap taps don't have any alignment devices and are to be avoided.
I've seen several side right cups that looked cross threaded but it turns out the cups were so badly deformed they are useless.
And always put lots of grease in the bb threads. It keeps the water and grit out, prevents rust and ruining the threads.
A bad cup. The first part threads in okay and the face sits crooked. I have several of these in my training examples. All are from bsos.
If it's the right side, a cartridge bb will stay pretty straight as the spacer and bearing part will self center in the shell. use one of those to try to clean up the treads. yah, the occ has a wwwwwiiiiidddddeee shell and axle.
Or take it to a decent bike shop that has a bb tap and have them chase the threads. shouldn't cost $20. the better taps have guides that slide in to each other (left & right) so they are always exactly on the same axis, centered and perpendicular to the shell. Not worth buying but worth paying someone who has a good set. The cheap taps don't have any alignment devices and are to be avoided.
I've seen several side right cups that looked cross threaded but it turns out the cups were so badly deformed they are useless.
And always put lots of grease in the bb threads. It keeps the water and grit out, prevents rust and ruining the threads.
A bad cup. The first part threads in okay and the face sits crooked. I have several of these in my training examples. All are from bsos.
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If you can see where the damage is...you can probably fix it with a thread file. Internal is more challenging than external...but still relatively easy-ish. The catch is your thread file needs to match your thread pitch...and good ones cost $10-20...which means you're probably better off taking it into a shop that has the right BB tap.
A Dremel tool with a polishing disk or wire wheel might be able to clean it up as well.
A Dremel tool with a polishing disk or wire wheel might be able to clean it up as well.
