If it's tightened properly there's no movement at the bolt. The bolt clamps the inner steel sleeve tight against the housing. The rubber simply twists to absorb the small amount of rotation, so nothing wears. Rubber control arm bushings on independent suspension systems work the same way, but they wear out because there's more movement involved.
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!