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#1
08-18-2018, 07:23 PM
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Retap BB Engish to Italian in MA
I got a worn out BB thread that I think I need to get it retap to Italian thread.(I've tried VO threadless BB but the thread is too worn and didnt work..) I thought of Harris cyclery in Newton and will give them a call but do you guys know anyone in MA who can do this type of work?
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#3
08-18-2018, 08:06 PM
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Wow, here you cant do stuff like that...
That's like 30/50 mins job...
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#5
08-18-2018, 10:58 PM
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So, ok... this has piqued my curiosity. If I understand the issue... the OP has a worn out or damaged beyond repair English BB, and wants to get it tapped out to Italian threads? Not just a simple chasing of some damaged threads.
So, here’s what I think would need to be done... I just want to put it down to see if this is actually what someone is going to do... First, since the Italian bore is about 1mm greater than the English bore, is the plan to just bore out the English threads then use the Italian taps to cut new threads? I guess you’d have to ensure there’s enough material in the BB shell to accommodate that. Secondly, with the English BB being 68mm wide versus the 70mm wide Italian shell, I’m thinking that a 1mm spacer would need to be inserted between the new Italian cups and each side of the shell. Does that sound right? If so, good save of a frame.
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#6
08-18-2018, 11:01 PM
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Quote:
Last edited by jtbadge; 08-18-2018 at 11:07 PM.
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#8
08-19-2018, 12:52 AM
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If you have italian BB shell that died pretty much you are screwed because the only chance is to or use one of those no threads BB which fits only english threading or just as somebody sugested, heat, braze and retap the thing.
But if the shell is english you can retap it to italian w/o any problems, actually is even better because italian BB is superior :P What you do is to use an adjustable tap... at least thats the one we used in my country, no idea if here guys use something else because is not just go and put the italian tap in there, .. the tap we used was exactly like a campagnolo one but adjustable, you go bigger and bigger super slow pace... once you it have almost there you go with the italian one to just finish the job... 50 mins work maybe... Slow process. The inconvenient of brazing with a filler and retap is that you end up heating the BB shell, which means new paint or at least paint the BB area, then put that frame in a table to check alligment because sure the frame will warp a little bit aswell. Too much of a problem.... The italian BB shells ive seen busted the master builder was just swapping the shell for a new one, was quicker for him than trying to fill up the thing with filler you know. Heat... drop the shell, braze the one in place, acid... cleaning... table and chase the new shell... well in my country stuff like that was a lot cheaper than do it here tho. Here the cost and time in doing something like that sends a frame atraight to the wall. BTW got two track bikes retapped to italian back in the day, old busted french track frames used to train in the road. Heavy reliable POS :P Last edited by ultraman6970; 08-19-2018 at 12:54 AM.
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#9
08-19-2018, 03:00 AM
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Theoretically, you only have to do one side as I doubt both sides would be damaged.
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#10
08-19-2018, 07:25 AM
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As an alternative, try a cartridge B.B. with two adjustable cups. My Colnago C40 has worn Italian threads on the drive side. I had pretty much given up in n the frame until I tried a Phil Wood BB. I installed with blue Loctite and it has worked great. My backup plan was to use red Loctite for a “permanent” installation if that didn’t work well but it has held up nicely for 1000 ish miles.
I seem to remember that to retap to Italian, the shell had to have brass brazed into the shell first, so not a completely simple fix.
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#11
08-19-2018, 07:26 AM
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[QUOTE=ultraman6970;2412750]
Quote:
-remove the old threads and some 'metal' since the 'far superior Italian threading' is larger OD. -Make sure the tap 'cuts' and resulting threading is perpendicular to the spindle and cup 'line'. If it's cocked, it will kill BBs..the only real way to do it is put the frame on a frame jig, and use a mechanized tap, like a frame builder would use. Do in bike shop with hand tools? I'm skeptical.
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#12
08-19-2018, 11:49 AM
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The trick was that adjustable tap, never ask where the builder got that from tho, one of those obvious things you never think when you are a kid... dude fixed me 2 track frames with that, saw him doing several more the years I spend just wasting my time in the shop :P
The tap was adjustable but had a pilot in the middle aswell like the campagnolo one, dude is dead so I cant call and ask him where he got that adjustable tap...
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#13
08-19-2018, 11:51 AM
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Here is a thread about it, with tools the dude used...
https://www.bikeforums.net/bicycle-m...periences.html
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#14
08-19-2018, 12:09 PM
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So, basically describing the process I surmised earlier. Bore it out just enough to get rid of the damaged English threads. Then retap using Italian taps with whatever method to ensure parallelism in the shell on both sides. Issue is primarily whether there is enough material left after boring to be able to retap with the Italian threads.
I’ve never heard of an “adjustable tap” so I don’t know what that’s all about. I didn’t notice any reference to one in the linked thread.
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#15
08-19-2018, 12:10 PM
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Quote:
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