Just removed my drive side Middleburn R01 on UN55 for a clean and found this washer behind. I don't remember installing it and can't see what purpose it serves, being a square taper BB it can't be for chain line... Is this likely to be part of the crank assembly or the BB, and what's it for?
It's bizarre, on this other one I have it appears to sit above the tapers, but there's no way that's happening here. There's a lip above the tapers where it's 17mm. Washer is no bigger than 16.6mm. I'll live without it until the BB fails I guess.
Just removed my drive side Middleburn R01 on UN55 for a clean and found this washer behind. I don't remember installing it and can't see what purpose it serves, being a square taper BB it can't be for chain line... Is this likely to be part of the crank assembly or the BB, and what's it for?