Bicycle Mechanics - Bottom bracket blues.. ideas?

I recently bought a vintage steal colnago which someone at some point "upgraded" the BB to one of those crappy 2 piece sealed cartridge units, where one side is made outta plastic.. if you've ever installed one of these our removed them you'll know they are death to get on our off cause they seem to be to big for the shell..who ever engineered these things should be shot. anyways im afraid the BB stretched out my bottom bracket shell, I installed a proper Dura ace 3 piece bottom bracket,and anytime I ride the fixed cup keep coming loose.. isthere anything Ican do besides Loctiting it in there? I mean im for that if it will actually stay in there and not come loose when im 50km from home.. but what if i Have tto remove it someday, how would I do that?

Is your bottom bracket shell threaded English or Italian? Italian drive side cups have to be installed VERY tight or they will loosen spontaneously. Are you torquing them sufficiently?

If it's English and someone tried to install an Italian bottom bracket, that could be your problem.

If the threads are really damaged and "chasing" them won't clean them up, then "Blue" (Grade 242) Loctite will keep the cups from loosening and still be removable with hand tools.

BTW, the Shimano bb's with the plastic cups aren't that bad if you install them right. I've installed several and they work fine. There is no way a plastic cup "stretched" your bottom bracket shell so if it is damaged it was from something else.

I personally have never had a problem removing or installing a sealed BB, even the kind with the plastic loose cups. I have this style BB on my two most used bikes at the moment.

As to keeping an adjustable BB from coming loose, Loctite should not be necessary. What type of tool are you using the install the fixed cup?

The BB is italian threaded, had an italian one in there, I can almost thread the whole thing in with just my fingers, it gets a little harder near the end. Ive got a proper wrench for the fixed cup.. I'll try torquing it down as hard as I can tommorrow and go crank up a hill down the street a few times to see if it will hold.. if not I'll try the loctite.

The only thing BB cups need is proper torque, italian or not. Except in extreme cases.

The only thing BB cups need is proper torque, italian or not. Except in extreme cases.
Well, the OP's first posting implied the bb threads were damaged so my first thought was that this was an "extreme case". Now I'm not at all sure it's not just a case of improper installation.

I can almost thread the whole thing in with just my fingers, it gets a little harder near the end.

That you can thread it in by hand is a good thing. BB cups are not designed with interference threads so unless there was threadlocker applied to the cup threads, it should thread in by hand.

Well I torqued it hard as I could, which is really hard cause the wrench always slips.. luckily I didnt end up with any busted knuckles. I took it for a few hard rides and it seems to have worked, so thanks for the tips!

I never had to torque a BB that hard before, its the only italian one Ive had.. well I had another bike with an italian BB before, but I never swapped the BB out. I remember when I stripped the bike to sell it (it wastoo small) I couldnt even remove the fixed cup, go figure?

Here's a link to Park Tool torque specs (http://www.parktool.com/repair/readhowto.asp?id=88) page. Notice the 51-57 lb*ft of torque needed? That's extremely high and about the only thing I ever use that needs more than that are automotive headgasket bolts. And I need a 2-foot torque-wrench to achieve the 60-66 lb*ft needed for those. So tiny 10" bottom-bracket wrenches need like 68-lbs of force on the handle to get the necessary torque. On Italian BBs, I've used Sheldon's bolt-and-nut clamping method, but used to tighten the fixed-cup, and even then, I still needed a 2-foot torque-wrench to get the requisite torque.