[Andy]

I built a rig to check fan balance. I also had one that shook. I welded a disk onto a rod and machined it so the fan would attach to it. I mounted the shaft in a couple of bearings. I played with it untill it did not have a heavy spot. I have also expeienced a bent pulley. Replaced the pulley and all was fine.
Here is a pic of the fan I put on my coupe. It keeps the engine very cool.