An improved self-adjusting automatic slack adjuster for reducing slack in the brake of a vehicle, in which a one-way clutch assembly is arranged in the housing of the automatic slack adjuster housing such that a thin-wall region of the housing associated with the gear drive of the one-way clutch assembly is located outside of a load path through which brake applications forces are conveyed from a brake actuator to a brake cam shaft upon which the automatic slack adjuster is located. The new positioning of the one-way clutch assembly drive results in unexpectedly lower stress levels in the automatic slack adjuster, resulting a more durable slack adjuster and permitting surprisingly large increases in slack adjuster capacity rating.