The invention is for automatic slack adjuster for an automobile with a housing having an aperture for receiving a brake cam shaft comprising of a worm gear coaxially mounted within the said housing aperture and configured to coaxially engage the brake cam shaft, such that the said worm gear and said cam shaft rotating together about a first axis. The arrangement has a bore with a single open end for receiving a worm clutch shaft. The said worm clutch shaft is mounted in the said housing to rotate about a second axis, which is perpendicular to first axis. The invention has only one side opening. The thrust load from the worm shaft is transferred through the thrust bush through the main housing of the assembly.