Note: This procedure is to make it easier to remove GEM brake drums before they rust to the hub. The drum must already be off in order to drill and tap the threads.
It is not uncommon for GEM brake drums to become stuck to the hub. This makes removal frustrating with the risk of damaging other components. A large gear puller or slide hammer is often needed. Do not attempt to remove the drum by pulling the studs. The studs go all the way through the spindle. I’ve discarded the small tapered drum screws on all of our vehicles as these are only used by the factory to prevent a drum from falling off during assembly. Do not use these tapered holes to drill and tap as they are already too large. Notice the hole I drilled in the image below. Once the drum is removed, drill and tap two 1/4"/20 holes near opposite studs so that threading in two 1/4"/20 bolts will push against the hub and thereby press the drum off. I have never had difficulty removing GEM drums since.
Daniel