Airplane crank flings are much larger than car flanges. There is a special tool to stretch, and walk it on with. What we do is warm up the seal, and unhook the spring ends, then walk it over the flange. After a little while it shrinks back to size, we hook the spring back together and using contact cement push it into its place in the case. Sometime we take a razor, and slice it to get it around the flange.
Just wondering if this could be considered.