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· chamois creme addict
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Despite my stance of never owning a bike with an Italian threaded BB (never say never, right) I ended up getting a 2008 Colnago Extreme Power. I built it up with Record UT cranks. Before building, a local shop chased the BB threads and faced the shell with the Campy cutting tools. He also installed the cups with some Ti prep as the BB shell is titanium.

Ignorning the Campy instructions for loctite and hand-tightening, I torqued the cups down to the recommended torque of 35 Nm or 26 ft-lbs. I installed the cranks and torqued the fixing bolt to 60 Nm or 45 ft-lbs. I have ridden the bike for about 10 hours, and I am pretty sure somewhere in the last 3 hours the drive-side BB cup worked its way loose. Unfortunately this was during a 3.5 hour road race and I was oblivious to the problem. The cup backed out a little ways (1-1.5 mm), by my reasoning it could only back out until the wave washer in the non-drive cup was completely compressed.

After getting home from the race I saw the gap between the BB shell and the cup and I disassembled everything and evaluated. I cleaned up the BB shell with degreaser and alcohol using a brush to get all the anti-seize out of the threads. I also cleaned the threads of the BB cups. I then threaded both cups in and I am surprised by the amount of play of the cups in the threads as I thread them in. There is definitely more play in the threads than any other BB/frame combo I can remember. The play is similar on both drive and non-drive sides, however there is slighty more play in the driveside. By "play" I mean that with the cups threaded in but not tight against the shell I can "rock" them in the threads. Visually inspecting the threads, it does appear the drive side threads did get a little damage from the hard riding with a loose cup. The peaks on the threads are not quite as sharp as the non-drive side (which did not come loose).

So, what to do here? Should I re-install the cups with teflon tape and torque the drive side to a higher value? Should I re-install using loctite? I don't have purple, but I would not be afraid to use blue. Should I re-install new BB cups, even though the threads look OK on them? Sell the frame and get something properly engineered with an English BB?

Sorry for the lengthy posting.
 

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sloppy threads...

It sounds like whoever chased the threads oversized them, or even more likely, they were oversized to start with. Whoever chased the threads should have noticed that the chasing tool did nothing if the threads were oversized to start with. If the mechanic who chased the threads took out any significan amount of material, it's his work that screwed things up.

The loctite method is probably your only salvation. Would you sell that frame to someone, knowing that the BB threads were messed up?

Get the purple loctite and do the job right. FWIW, I've owned four Italian threaded frames (before the days of outboard cups), but never had any problem with the right BB cup loosening up. I never used anything but grease and the proper torque.

I have installed two sets of Campy UT bearing cups this year (English threaded). They both had a large amount of yellow thread locking material on the RH cup. So much in fact, that it took 10-15 lbs of torque just to thread the RH cups into place, before they touched the face of the BB shell.

Even a right hand threaded cup should not back out until after it has loosened. It's not the LH thread that causes it to loosen in the first place.
 
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