A precleaner arrangement for separating a portion of entrained material from air flow air entering an engine air cleaner; the precleaner arrangement comprising: (a) a precleaner housing comprising a central hub and an outer ring surrounding the hub; (b) at least a first flexible air deflection vane with a fixed portion secured to the precleaner housing and a deflectable portion; the at least first flexible air deflection vane being positioned between the central hub and the outer ring, each flexible air deflection vane being secured to the central hub and outer ring at the fixed portion of each vane; (i) the deflectable portion including a curved section extending from the fixed portion and a tail section extending from the curved section; (ii) the fixed portion of the first air deflection vane defining an upper terminal edge; and (iii) the deflectable portion of the first air deflection vane defining a perimeter including an inner side edge oriented adjacent to the central hub and an outer side edge oriented adjacent to the outer ring and a lower terminal edge bridging the inner and outer side edges; each of the inner and outer side edges extending from the fixed portion; the tail section defining the lower terminal edge; characterized in that (iv) the tail section has a variable thickness in a radial direction being greatest at the inner side edge and decreasing in thickness to the outer side edge. (a) a precleaner housing comprising a central hub and an outer ring surrounding the hub; (b) at least a first flexible air deflection vane with a fixed portion secured to the precleaner housing and a deflectable portion; the at least first flexible air deflection vane being positioned between the central hub and the outer ring, each flexible air deflection vane being secured to the central hub and outer ring at the fixed portion of each vane; (i) the deflectable portion including a curved section extending from the fixed portion and a tail section extending from the curved section; (ii) the fixed portion of the first air deflection vane defining an upper terminal edge; and (iii) the deflectable portion of the first air deflection vane defining a perimeter including an inner side edge oriented adjacent to the central hub and an outer side edge oriented adjacent to the outer ring and a lower terminal edge bridging the inner and outer side edges; each of the inner and outer side edges extending from the fixed portion; the tail section defining the lower terminal edge; characterized in that (iv) the tail section has a variable thickness in a radial direction being greatest at the inner side edge and decreasing in thickness to the outer side edge. (i) the deflectable portion including a curved section extending from the fixed portion and a tail section extending from the curved section; (ii) the fixed portion of the first air deflection vane defining an upper terminal edge; and (iii) the deflectable portion of the first air deflection vane defining a perimeter including an inner side edge oriented adjacent to the central hub and an outer side edge oriented adjacent to the outer ring and a lower terminal edge bridging the inner and outer side edges; each of the inner and outer side edges extending from the fixed portion; the tail section defining the lower terminal edge; characterized in that (iv) the tail section has a variable thickness in a radial direction being greatest at the inner side edge and decreasing in thickness to the outer side edge.