How to Install a Rivnut with Simple Tools

Some [insert your favorite curseword] stole the catalytic converter off my Honda Element, which ended up costing mid-four figures to replace. Thank heavens most of it was covered by comprehensive insurance… Not wanting to go through that particular hassle again, I decided to install catalytic converter shields on both the Element and on my Tacoma. The Tacoma has not one but two cats, and replacing them would break the bank. Given that having a mechanic install the suckers would have doubled the purchase price, I crawled under the vehicles and did it myself. Thanks for the loan of the jackstands, Jeff.

The shield for the Element went right on, screwing into threaded holes that were already in the frame. The shield for the Tacoma was another story: I had to drill four new holes in the frame and install rivnuts (also known as nutserts or rivkles), to mount that sucker. I’d heard of rivnuts before, but I'd never used one. A rivnut is a cross between a rivet and a nut: it’s a metal cylinder, threaded on the inside, that fits into a hole. With the proper tool, you can “squash” the cylinder like a rivet so that it fills the smooth-sided hole snugly, creating a threaded hole where there was none before. If you don’t have the right tool?

Well, there’s where this gets interesting: you don’t actually NEED the tool, it’s just convenient to have. If you have a reasonably well-stocked tool chest, you can install a couple of rivnuts without the expense of a new tool. Not that most people balk at new tools, but.

Here’s what you’ll need:

• A rivnut (and a hole to put it in)
• A hex-head bolt that fits the rivnut, about two to three inches long
• Two flat washers that fit the bolt
• Two hex nuts a couple of sizes too large for the bolt
• A pair of wrenches; one to fit the hex head and one to fit the hex nuts. Good pliers will work for the second wrench. 

Here’s how this works:

1. Assemble your tool: put one washer, the two oversize nuts, and the second washer onto the bolt.
2. Thread the rivnut onto the bolt finger-tight with the flange against the washer.
3. 
   Grab the oversize nuts with a wrench or pliers and insert the assembly into the hole, rivnut first, until the flange snugs up against the metal. Make certain the rivnut is in straight and in the proper orientation. The flange will keep the rivnut from going all the way through the hole and out the other side.
   
4. While pressing the whole assembly against the metal with the nuts and flat washer, place a second wrench on the bolt head and start tightening. For small to medium nuts, a 3/8-inch socket and ratchet will suffice, for bigger nuts you may want to stick with an open-end or box wrench.
5. 
   
   Continue to tighten the bolt until you feel a snap. That’s the rivet part collapsing on the back of the metal. At this point, it will become easier to tighten the bolt. 
6. Back off the bolt a couple of turns and see if the assembly wobbles. If so, retighten and give the bolt another quarter turn.
7. Once the rivnut is fully seated, remove the assembly and move on.

Some points to remember:

Rivnuts are designed to fit specific thicknesses of metal and also require a specific “work hole” diameter. If you don’t already have a hole to work with, I suggest investing in a step drill bit for drilling metals. It’s a lot easier than trying to drill a series of holes of increasing size or a single full-size hole.

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