2005 Chevy Trailblazer noise on left turn

My 05 trailblazer makes a rattle when warm and turning to the left.sounds like a shield or rubbing of some sort.doesnt do it all the time.To the best i can tell,it does not relate to brakes as if i tap them when it occurs,it doesnt change.Has the tonal quality of a heat sheild,say in the exhuast area,but does not explain the turning problem.Any ideas?
thanks