I guess I've lurked on this site for long enough and it's time for my first post. I had the same issue with my Rock Hard rear bumper / tire swing. They give your two rubber bumpers to choose from - one too small and one too large. I started out with the smaller one and used a couple of fender washers to make it the right thickness. The method they use to attach the bumper to the tire swing is not well thought out. Using a self tapping screw (course threads) to attach something to a relatively thin wall tube will not lead to anything good. On one of my first off road trips after installing the rear bumper / tire swing, the self tapping screw snapped off. I drilled it out to a larger size and although the larger screw didn't snap, there is just not enough thread "purchase" to stay tight. I realized I had to figure out a better way to do this. As you can see in picture 1, the rub rail shows a lot of wear from the bumper becoming loose and the screw head coming into contact with the rub rail. A little sanding and some spray paint took care of this. Picture 2 shows wear marks on the tire swing as well. Picture 3 shows the tire swing closed and the larger bumper resting on the rub rail (to show that it is too thick). Picture 4 shows some 1" fender washers, some 1/4X20X1" socket head bolts, some 1/4X20 rubber "well nuts" and the thicker bumper. Picture 5 shows that I have taken a longer 1/4X20 bolt and attached it to the rubber bumper with some nuts with nylon inserts. Line the nuts up so that your drill press chuck jaws can grab them properly. Picture 6 shows that I used a sanding drum in a rotary tool to reduce the thickness of the rubber bumper. Picture 7 shows the final results. Obviously, you will have to measure and take a little off at a time so that you don't remove too much material. You want a very snug fit. Picture 8 shows that I have cut off the head of the well nut with a razor blade (so that the rubber bumper can sit against the tire swing) and attached it to the bumper. Drill the tire swing out to accept the well nut, put it in place, tighten the socket head bolt and the rubber will expand and hold the bumper in place. This rubber joint is much better than using a self tapping screw to attach the bumper as it soaks up the vibrations and does not loosen up. Since I made this modification, I have not had any problems. It now takes a really rough road before I hear any noise from the tire swing.
