Rivnut install questions from a rivnut dummie

So I got my stuff from dieselgeek aka Jim for the metal belly pan, and the only big
question I have is on the rivnuts.

They have a flange on one end and I am guessing that I have to drive it into place smacking the flanged end,
and then expand the flange by tightening a bolt to the point where it mushrooms inside the
frame rail. Is this correct? Does this work? I mean the nut won't spin?

I am doing this project this weekend and I want to have it go well.

Tap rivit nut into place, Insert bolt (Through metal plate) and Tighten. You have to keep pressure againt the Rivit Nut to kepp it from spinning sometimes. Really cool fasteners....

For the rear 3 holes in the subframe: Take a rear bracket, hold it so the indented side is down, push one of the 7 bolts up through, screw on a riv-nut so the flange is on top of and against the bracket finger tight. Push the riv-nut up into one of the holes in the subframe (no need to drive it in, the hole is big enough ).Hold the bracket with pliers and tighten the bolt. The riv-nut will collapse as you tighten the bolt. You will feel the bolt bottom out when done. Make sure as you tighten the bolt, you keep pushing up on the bracket to keep the riv-nut flange against the subframe. When the bolt is bottomed and fairly tight, back the bolt out and move on to the next riv-nut.
For the front brackets, hold the bracket so the top flange that is cut off is toward the rear. Push two bolts up through the holes and screw on two riv-nuts as before. Push the assembled bracket into place and tighten the bolt until bottomed and fairly tight.
I coated my riv-nuts with silicone seal prior to assembly. Also, on the front brackets, I ran a thick bead of silicone around the hole on top so it would seal when bolted into place on final assembly.
Make sure you know exactly how to do this before you start, as you have only ONE chance.
Don't be afraid to ask again.

I had the same question when I got mine yesterday.

What is the silicone for?

You can get a whole Rivetnut kit with the tool to compress the nut made by MARR. They make really good quality products. I bought mine at Princess Auto in Ottawa for about $50.00 Cdn funds. www.princessauto.com

So the rivnut must be aluminum, ok.

But if I don't have to drive the rivnut into the frame rail, what keeps it from turning? I see it has splines on the outside and I thought that implied a mild driven initial fit to prevent rotation.

The silicone is to seal the installation from corrosion. When the riv-nut collapses in the hole, it squeezes the metal of the subframe and the splines help grab the frame to keep it from spinning in the future. No need to buy any special tools. It works with a regular wrench.

I forgot to ask earlier what the silver colored bolts go to. I know that two of them are to connect the plate to the rear bracket, but what are the other two for?

Do you mean the long bolts? I think people are getting four of those instead of the required two.

Don't use the long silver ones in the rear brackets. They are for the front yoke where it connects to the forward brackets.

Right I got four. Assumed they were "shear" bolts designed for off-road adventure, hence the spares.

I am assuming the rear brackets are the long ones (not the thin almost washer brackets (3)). I saw a picture that used the silver colored bolts to connect the plate to the brackets. I guess I got extras.

The two long brackets are the front ones. They bolt to the front frame rails. The three little brackets are the rear ones. They bolt to the engine/trans subframe.