It was an anti-squeal device, which dampened out any scrubbing noise the brake shoes might make on a brake application. If you really want one, and the drum has the proper groove for it, get an oldtime screen door spring and stretch it around. I can't see an overriding reason to use one!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!