The slack adjuster is part of the braking system, what is the maximum play allowed with the brakes off?

There should be no more than 1 inch of play in any slack adjuster on the vehicle, with the brakes off. This is the maximum amount of movement that should be allowed between the brake lining and the drum or rotor before the brakes start to engage. If the brake play is more than 1 inch, it could be a sign of a problem with the braking system, such as worn brake linings, damaged brake drums or rotors, or a faulty slack adjuster.