Here are a couple of links to help you along with that job.
Removing enough stuff to get to the rear caliper:
http://www.goldwingfacts.com/1500finaldrive.htm
Rebuilding the rear caliper:
http://goldwingdocs.com/forum/viewtopic.php?f=11&t=56
The how-to article is for a 1100 caliper but the 1500 is much the same. Should be able to do it from these instructions.
Removing enough stuff to get to the rear caliper:
http://www.goldwingfacts.com/1500finaldrive.htm
Rebuilding the rear caliper:
http://goldwingdocs.com/forum/viewtopic.php?f=11&t=56
The how-to article is for a 1100 caliper but the 1500 is much the same. Should be able to do it from these instructions.