Use of riv-nuts on rear bumper
 

I was thinking about putting riv-nuts in the mounting surface of my rear fenders to make installing and removing my rear bumper cover easier. A neighbour thought it may not be a good idea because riv-nuts can come loose after a while with constant vibration. I was wondering if anyone here had experience using them on their car?

I use riv-nuts in fiberglass installations. Keep the screw lubricated and I have not had them come loose. The riv-nut goes into the fiberglass side. The screw comes through the steel or other supporting side.

OK, thanks Jamie, I'd like to put them in the fiber glass bumper cover, as you've done, but the bolt will go up into the steel fender more directly & easily than down thru the fender into the fiber glass cover.

Wouldn't the riv nut be more secure in the steel?

I think so, i'd prefer it in steel. I'm going to try this weekend.

I find that riv-nuts do not hold well in steel. They do not compress enough to grip securely. You can put a washer behind them to help. The fiberglass is thicker so the material will grab the knurled section and prevent them from spinning.

For steel use a PEM nut. It is designed for thin sheet metal.

Unless it's touching the exhaust, the rear bumper is relatively free from vibrations.
I got by with two M10 allen bolts when I removed the pads - they never needed tightening adjustments - 4 years.
When was the last time the sheet metal screws in your rear valance came loose?
Bill K

If the rib nut is not compressing properly you may be using the wrong rib nut

Please make sure the rib nut grip range is compatible with the material thickness

David