The bar moves in 2 directions, side to side and up/down. I had that problem in 2 places because I had to use a bar to raise the bar height. Drilled and welded a nut too the top and side with bolts to clamp the tops and sides of both receiver connections. Made a huge difference. The movement in the receivers allows the car to move the rear of the motorhome. Found that those rattle clamps seem to keep getting loose. Need to tighten the clamp many times. It is not sway, it is the dog wagging the tail effect.