fastpedaller wrote:
I'd be reluctant to try and dislodge the outer seals because (from the FSA experience yesterday) they fit into a groove in the outer race, so could be easily damaged.
The seals fit in exactly the same way as those in every other cartridge bearing; I have removed and refitted hundreds. In a perfect world they would come out with no risk of damage. We are not in a perfect world, and removing them -even if you make a small nick in the edge- is as usual the lesser of two evils. [IME water always gets in past the seal lip, even if there is a small nick near the outer edge, presumably because grease either blocks the hole or is always coming out of it. This is especially likely in the case of the BBs in question because the bearing centres usually have no shoulder, and no labyrinth, i.e. they are likely to leak like sieves.]
I note your comment about retaining compound, which leads me to ask.... Do the expensive separate bb units without a structural sleeve use retaining compound? can we just rely on a small preload to hold the outer races?
they should use a different fit quality (on the diameter) between the parts, and retaining compound is not normally required. However if wear occurs, I've added it when rebuilding such units. It only takes a few microns of wear to make a difference.
There's another possible bonus to this idea, in that an additional shield (eg made using old inner tube) could be sandwiched between each cup and its bearing, this could also act as a 'spring washer' thus preventing the bearings rotating in the cups?
You can indeed manufacture additional seals/shields. As reported elsewhere I have made brass shields and used them in BB units like this as well as suspension pivots in MTBs etc. However I would not use inner tube rubber unless it was proven not to swell up and deteriorate in the presence of the lube you use. I would also not use any plastic or rubber if the BB sleeve sees a decent preload; it will simply compress. Brass shields can be used with or without a compressed centre sleeve. Making brass shields is a lot of effort but if you do it right the shields will outlast several sets of bearings.
cheers
