Don, on a QAxx and a QAxxA those four bolts should not have to be messed with... There should be spacers on them that allow them to be tight but not so that the bracket will not slide up and down. If you look at the exploded view of the QAxxA subframe item #8 is the spacer. However, on a BB36 or a CW36 you may have to loosen those 4 screws to adjust the belt tension.
Steve S., you should still be able to fashion some sort of latch to keep it from coming loose. Easiest would be something like the wire that Charlie posted.