There are two mentions of dished Lucas fans in this thread. So I’m not sure. The alignment is perfect. The material is somewhat fibrous, a little like gasket material.
“If concentricity is causing the fan interference, I’m not sure how I could fix that. I can’t use the substitute fan from my rebuilder, because note how the Lucas fan is dished in the center. This gives extra clearance for the fan tips, whereas the flat “conventional” fan scrapes the body.”
“Thought just came to me - if 15mm fans are very common for Lucas alternators, maybe I could use a fan for some other Lucas model instead. Many seem to have the dished center, which I’m thinking is important to maintain proper pulley alignment?”
Rick