I tried using a 15 to take tension off of the belt using the supercharger tensioner but the bolt would spin before I could get enough tension off the belt. I haven't tried using a t50, that will be where I start nextYou can use an open end 15 to put on the back side of the blower tensioner and push down. Or you can use a t50? I dont remember the exact size. On the blower tensioner as well to push it down