Help with BB size replacement

[B]I’m replacing an old spindle/cup/caged bearing 113 mm Shimano BB arrangement. Has to be JIS taper to reuse my 105 cranks. I want a 103 mm unit for a revised chainline as I’m going fixed. Knowing the existing unit is Shimano and frame width is 68 mm (double checked) I thought it was British /ISO threads. Hence was thinking of the Sugino/Tange unit of that size would do.[/B]

[B]However I just noticed the cups are marked 36 x 24T and a spare Shimano shell slips through. So I think I’ve got an Italian job ! Low and behold they measures 36mm.[/B]
[B]Can the assembled suggest any alternatives. All I can think of is a Italian threaed Shimano UN54 unit at 107 mm and space things out a bit front and rear. Not sure if this type of spindle can be found as a spare in very short lengths.[/B]
Cheers in advance

never heard of 103mm with italian thread but if you don't sort it out you could try to put 107mm and then put the chainring on the inner side of the crankarm. this should compensate the bb lenght more or less fine

Try this: dura ace bb-7410 italian

This has the threads you need and a 103mm axle.

This is just one:

http://cgi.ebay.com/Shimano-Dura-Ace-Italian-bottom-bracket-7410-8-speed_W0QQitemZ150358658611QQcmdZViewItemQQimsxZ20090713?IMSfp=TL090713192003r3208

NOTE: most BB-axles are not symmetrical.
That means, if the length is 10mm shorter, it's not 5mm on both sides.
So, the chain line does not necessarily move 5mm inwards.

You either have to try and be lucky, or you need an extensive list of the manufacturer (doesn't exist, even for people working at those companies it's alsost impossible to get this info).

E.g.:
Shimano BB-UN54 LL113mm vs. MM110mm.
It's 2.5mm difference on the RH side and 0.5mm on the LH side.

Thanks for the feedback. Some good pointers.

NOTE: most BB-axles are not symmetrical.
That means, if the length is 10mm shorter, it's not 5mm on both sides.
So, the chain line does not necessarily move 5mm inwards.

According to my LBS that is exactly what it does: 5mm shorter IS 2.5mm each side. I actually watched very experienced guy swapping out my BB to get a perfect chainline and mumbling, "Well, if we need another 1mm off there I want to come down from 115 to 113." But yes, they are of course asymmetric.

Then your dealer is wrong.
In some cases, it's true that, if it's 5 mm shorter, it's 2.5mm at both sides, but not necessarily.

Sorry, I don't want to use this tone or sound arrogant or so, but I've been at Shimano Inc. for 9 years, so I think that I know a bit what I'm talking about.

It's just a general warning/tip/information that could be useful.

Indeed, almost all BB axles are asymmetrical, but certainly not all in the same way.
We're talking about millimeters difference, but that can be important for single speed.