Hello Folks,
I read the cupped washer exerts force on the outer edge only, which would mean it shouldn't be flattened?. The stepped washer has an O/D of 25mm, and the inner diameter, which goes inside the cupped washer is 19.5MM. The overall thickness is 4.6mm, with the part that goes in the cupped washer 3mm, shoulder 1.6mm. I think that thickness is such that when torqued up the stepped washer contacts the sprocket shaft, and is designed to preload the cupped washer correctly?.
Be aware, when I torqued mine up, the stepped washer cracked into six or so bits, it looks to me to be cast, yes cast!, so I made up a few out of mild steel, with a thicker shoulder of 3mm, the inner dimension the same at 3mm. I marked the bolt, washers and sprocket with tipex, the cupped (belleville) washer does turn very slightly sometimes, but by a few degrees.
The sun is shining in Scotland, time to ride!
Alan.