This particular type of rivet nut is really very sturdy, and it takes a fair crank to get it collapsed during installation. I had a hard time keeping it from spinning... Turned out that drilling little holes, inserting finishing nails, and then holding everything in place with a cable lug as a shim worked pretty well. This WAS kinda time consuming, and I broke several tiny drill bits in the process. Next time I would try the 'extra nut' method; threading an extra nut up between the flange and thru bolt, and 'loosening' the nut to collapse the rivit. The 'JackNuts' I used in other areas of install, like for the PVC conduit under the car, are much lighter duty, and much eaasier to install, but probably have less pull out strength...