Ultegra 6700 11-28 cassette lockring crush washer
I removed the cassette on my bike for the first time last night and whoever put the lockring on really torqued it down, thank god I just bought a set of the vice whip pliers or I would have never got it off.
Anyway, the lockring crush washer was smashed and broken in two pieces. I have a new washer for a 12t lockring, it fits properly around the threads but overhangs the lockring by about 1mm. Do you think I could use it? Is it even necessary?
That washer is not essential. Don't use the larger one because the chain will probably ride on it and cause skipping and unwanted wear on the cog teeth.
A better way of removing an extra tight lockring is to use the skewer to hold the lockring tool in place while loosening with a crescent or open end wrench.
If you have any doubts, use a torque wrench when installing the lockring.