Midas Cars Forum - www.midascarsforum.com

Does anyone else hate these blasted things with a passion?

I can see the point when you want a thread in a box section but not when both sides of the panel are accessible. My car is littered with the ones that fix with four points and then rust to the screw or bolt resulting in a spinning fixing when trying to undo it.

The upside is that my new pedal box is now securely fixed to the car, the old one had been fixed with screws running through the captive threads into rivnuts with a huge stack of penny washers used as spacers. Another upside is I've now got a years supply of penny washers.......

They can be very useful. They can also be a right pain, but the ones I'm thinking of weren't inserted tightly enough. I'm just glad I found out before they went rusty as well!

(It wasn't me who inserted them, either... )

I've got a few less holes for the water to get in through too!

I have several items for several applications. I have the aluminium rivnuts that are like small tubes. These can only be applied in thin walls.Then I have the anchor nuts that spread like a flower as you explained. These are common for our thick wall GRP cars. I have them in my car as well. I have a special tool from MEMfast and it works great. With a simple mod I can use it for both type nuts. Because it works like a screw instead of a rivet gun tool it's much better to adjust the load.
But for everything that gets wet or can vibrate loose I use rubber nuts. These are splendid but require very long bolts/screws to tighten. I've never had issues with these.

I've got a few rubber nuts on mine already, I expect that's what'll be holding my undertrays on later this year.