and rear pairs are spaced laterally across the top or roof of the motor vehicle in fixed spaced apart relationship when the bars 13 or 14 are inserted into the respective passageways of either hold down member 23 or hold down member 23 39 accommodation is automatically made for the width or distance between the tracks or slats 11 and 12 therefore a variety of bars on mounting racks or load carriers may be accommodated without the necessity for measuring or accounting for precise fit furthermore it is noted that the securement is fixed and that the securement is theft proof since the complete disassembly of the mounting means would be necessary in order to remove the load carrier or any sports articles that may be carried thereon in view of the foregoing it can be seen that the mounting means of the present invention whether it takes the form of the brackets shown in fig5 or 6 provide a novel means for mounting a load carrier or rack crossbars onto the tracks rails or slats of a conventional vehicle inasmuch as the crossbar may be slid through the open ended passageways or channels on either of the mounting means embodiments the width of the rack or the width of the slats or tracks may be accommodated furthermore it can be seen that the mounting means of the present invention compensates for a slope or curvature in the roof 10 of the vehicle itself by providing a floating hold down member such as represented by numeral 23 39 in fig4 that tightens upon the end of a crossbar inserted through passageway 24 when the fastening screw or bolt 30 is tightened the bolt causes the hold down.