Help wanted on bike build

Quoted post said:

Originally Posted by neily42 [IMG]/img/forum/go_quote.gif[/IMG]

Hi all im new here so a big HELLO. I've got an old claud butler which ive just had powder coated. It was a 21 speed but I've changed it all to a 27 speed. I have changed every thing to do this ie rear derailleur, cassette shifters, chainset, bb. Now it was a square tapered bb what was in originally and was a 73x113, I've changed it to an shimano octalink 73x113 with a hollowtec chainset it all fits together nicely BUT, when i shift up on the front derailleur it shifts up each chain ring nicely but wont come down as easily,I've been looking at the bb but not sure I've got it in correctly.does the thread part of the bb need to be flush with the frame, as the way it is now there is about 3-4mm it could go back to the frame but the other side where the arm is there would be only a few turns to secure the bb have I the right size or can it just be adjusted to suit any help cheers.

The External BB cups should be threaded ALL THE WAY into the BB shell & be flush with the BB shell's edge (there should be NO exposed threading when an External BB cup is properly installed) ...

• if you are having difficulty threading the cups into the BB shell AND if you have been using the proper tool [there are several brands & models] ...
  
• then, presuming that the cups are SHIMANO, you may need to take a LARGE (~11"😉 FLAT FILE & knock the tips of the threads down (i.e., reduce the outer diameter of the threads) because it seems as though there were some (many!?!) cups where the CNC machine which manufactured the cups does not seem to have been adjusted properly ... YOU PROBABLY ONLY NEED TO REMOVE A MINIMUM AMOUNT OF THE TIP OF THE TEETH ... ALL THE WAY AROUND ...
  
• WIPE THE GREASE OFF, FIRST
  
• WHEN YOU ARE DONE REMOVING THE ANODIZING + TIPS OF THE TEETH, WIPE OFF & RINSE THE RESIDUAL FILINGS OFF WITH SOAP & WATER ... dry
  
• regrease test fit
  
• repeat as necessary
  

[*] re-install FLUSH with the BB shell
[*] re-install the crankset

Hi thanks for rhe reply. I can screw the bb chain side all the way in I have the proper tool but when it comes to screw the plastic cup in on the other side tjis wonr screw all the way home. This is what's making me believe its the wrong size. The original was just a bearing race either side and it collapsed. A guy I know replaced it with a sealed shimano bb, it worked fine on the old gear set up. So when I've ordered my new octalink bb ive just copied off the previous shimano square taper bb, and now I've came across this problem. Not sure if attacking it with a file will resolve the problem. Is there a way if measuring my frame to see what size I would need or is it to complicated once again thanks neil

My bad ...

I didn't read your description carefully enough & I thought you were using a Hollowtech II crankset with External BB cups ...

Try this ...

1. Screw the non-drive side in first (put some grease on the inside of the cup) ...
   
2. then, try screwing the driveside in ...
   

I know that you would think that it wouldn't make a difference, but sometimes it does.