Use of riv-nuts on rear bumper

[puddy]

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?

[jpnovak]

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.

[puddy]

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.

[obscene]

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

[puddy]

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

[jpnovak]

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.

[bkreigsr]

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

[Harpo]

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