Reagan ignored the War Powers Act in Grenada for example. Also, in the bombing of Libya.
Both were less than 90 days (60 days combat 30 days withdrawal).
On October 25, 1983, President Reagan reported on the use of 1900 U.S. forces to invade and occupy the tiny Caribbean island of Grenada. All U.S. combat forces were withdrawn by December 15 (i.e., ten days before the time limit the War Powers Resolution might be thought to have imposed).
On August 8, 1983, President Reagan reported that two U.S. AWACS and eight F-15 aircraft had been sent to Chad to assist that nation repel aggression from Libya.
http://www.mbc.edu/faculty/gbowen/warpower2.htm