Italian threaded cartridge BB

[icepick_trotsky]

I'm having trouble getting a cartridge square taper bottom bracket installed. This is a Shimano UN-72 BB. I've never installed one of these on an italian threaded bike before. Bike, for reference is a '91 Merckx Criterium, Columbus SLX.

Obviously, being italian, both sides thread righty tighty. But I can't get either started. Cartrige will thread a little bit in, then stop cold. Other cup won't start threading at all. I didn't try to force it because I didn't want to risk damaging the threads.

The BB looks backwards from most cartridges. You usually thread the cartridge in from the drive side, then put the other cup on the other side, right? The cartridge has and L and an R arrows which are the reverse of this, but shouldn't matter on an italian BB with symmetrical spindle, right? What am I doing wrong here?

Maybe just needs a face and chase?

Pic of BB:

http://i.imgur.com/cINJJ8ph.jpg?1

[Mark McM]

Yes, a chase and face is a good place to start. Are you sure that the BB is Italian? Italian threads are slightly larger than English/ISO threads, so obviously you would not even be able to get an Italian BB started into the threads of an English threaded shell.

From your photo, I don't see that the BB looks reversed at all. The right cup (not shown) should have a shoulder to seat against the BB shell, and the left cup should have no shoulder, as yours doesn't. Although most cartridge BBs come with the right cup already pressed on, sometimes when they are removed, the left cup is a tighter fit and the cartridge comes out with the left cup - was this BB removed from a different frame? In any case, this shouldn't matter when re-installing into a new frame - just thread the left cup partially into the shell, then install the right cup making sure that the cartridge aligns with the cup. Tighten the right cup as normal, and then continue tightening the left cup.

[colker]

Obv What am I doing wrong here?


http://i.imgur.com/cINJJ8ph.jpg?1

You are not building w/ campagnolo.

[icepick_trotsky]

It was my understanding that all Belgian Merckx were Italian threaded, right? Guess I should check the direction of the threads.

[colker]

It was my understanding that all Belgian Merckx were Italian threaded, right? Guess I should check the direction of the threads.

as he said: the size is different.

[nate2351]

It was my understanding that all Belgian Merckx were Italian threaded, right? Guess I should check the direction of the threads.

You would know if it was an English shell with an Italian bb, it wouldn't even start. I second chasing the threads, I've had to do that an almost all older bikes with Italian threads.

[monarchguy]

Just put a Shimano BBR60 Italian-threaded BB in my new-to-me EM Strada -- supertight. Looked up the price of the tap on Park's site and almost passed out. Anybody want to let me borrow/rent an Italian tap? Measured it before it went in,as I didn't know what flavor it was, and seems to be in spec. Maybe Shimano is making them tight?
-- Dan

[jtbadge]

You are not building w/ campagnolo.

I dunno, I think it's going to look pretty alright when it's done:

http://7169-presscdn-0-61.pagely.netdna-cdn.com/wp-content/uploads/2011/10/eddy-merckx-team-panasonic-8.jpg

[colker]

I dunno, I think it's going to look pretty alright when it's done:

http://7169-presscdn-0-61.pagely.netdna-cdn.com/wp-content/uploads/2011/10/eddy-merckx-team-panasonic-8.jpg

:beer::beer::beer:

yup

[weaponsgrade]

I had a similar issue once. It turned out that the threaded portion of the bb shell wasn't long enough to allow the cups to completely thread in. It was a quick fix. The shop just ran a tap through a bit further to cut some additional threads.

[rccardr]

Try cleaning the bb threads with solvent and a wire brush. PO may have used some sort of threadlock substance that is conking up the threads.

[Fivethumbs]

Do you have another Italian bottom bracket that you can thread in just to see if it's the shell or the BB? I have a Merckx SLX with an Italian threaded shell with a Shimano UN-52. The BB has the drive side thread cup attached to the BB so I thread the whole BB in and then screw in the non-drive side cup.

[oldpotatoe]

Chase threads with a good tool and face it as well since the RH cup sits against the BB shell. ALSO tap the RH cup OFF and grease in there, tap back on..place where creaks live. It IS the far superior Italian threading. If it were not, you wouldn't be able to get the 'Far superior Italian threading' BB to even start.:)

[oldpotatoe]

Just put a Shimano BBR60 Italian-threaded BB in my new-to-me EM Strada -- supertight. Looked up the price of the tap on Park's site and almost passed out. Anybody want to let me borrow/rent an Italian tap? Measured it before it went in,as I didn't know what flavor it was, and seems to be in spec. Maybe Shimano is making them tight?
-- Dan

Not uncommon. The thread is correct size but the 'pitch is a wee bit different. Yes, good tools are not cheap and cheap tools killing a expensive frame isn't cheap either. Where are you? I can chase your frame.