Am currently ressurrecting my old Ernie Clements roadbike. Unfortunately, one of the cones has cracked on my bottom bracket due to a stuck ball bearing. The current BB set-up is a Japanese Sakae SR-SC 1.37x24T with a 3U spindle. (Note - According to the Bonthronebikes website, this means the Shell width is 68mm and overall length is 124.5mm. LH length = 32mm. RH Length = 40.5mm. Middle length = 52mm).
I am finding it impossible to source another one of these Bottom Brackets (Cone & Bearing style), so was wondering if anyone could recommend a particular Sealed Unit as a replacement?
Its harder and harder to find loose cup/cone style BBs. Best bet is to go to an established LBS and see if they have any used spindles or cups.
But I would recommend getting a replacement sealed unit. They are fairly cheap and require no service once they are installed. Shimano UN26 come in a 122.5 spindle length or 127.5mm (msrp $12), UN54 in 122 or 127 (msrp $24)
As you see, it's an asymmetrical bottom bracket: the crankset side is 8mm longer. Most modern bottom brackets are symmetrical, at least inexpensive ones.
You can try to buy a symmetrical bottom bracket and use spacers to move one side of it. Usually, spacers come in 1mm, 1.5mm and 2mm.
A 127mm bb should work; a 124.5mm bb may work or not.
I had a 3T bb and used an YST 124.5mm bb plus a 2mm spacer as a replacement.
Look here at the bottom for specifications: http://www.yst-corp.com.tw/new/cartridge_bb01.html
Measure the distance A (between the spindle end and the bb shell) in the picture and make calculations.
For example, for 3U it says
L - 127.5mm, A - 32.48mm
If your A is 35.5mm, then you need a 3mm spacer to move the bb to the right.