What's your opinion of rivnuts?

So I need to remount my front skid (factory) which bolts to basically threaded punched holes in sheetmetal in the front. One of those holes stripped when I removed the skid, so I went to Fastenal and got some 8mm steel rivnuts and repaired that one hole. Appears to me to be a valid strong method of repair (as an aside, however, their web site recommends a 13.5mm drill for that hole; that works out to a little more than 17/32" but if you're using the nut and bolt method instead of the proper insertion tool, that is too large a hole for it to not spin. I had to clamp vice grips on the backside of the rivnut to keep the whole rivnut from spinning even though I'd oiled the nut and washer. 1/2" is too small; I do have a 33/64" drill but haven't tried it yet) although I don't know how these really compare to a traditional nut in terms of strength. Obviously the one that I've inserted is stronger than the factory method, but I have two more locations where I want to use these, one is on the transmission x-member where the transfer case skid mounts, and one is directly into the frame. In both cases the factory bolts are still present, but I can't remove them because the captive nuts have broken free of the bodywork to which they were originally tack welded. In one location, I can tack a nut on if that is really preferable; in the other, I'd have to cut the frame open to do so and therefore am really leaning towards using the rivnuts. In your collective opinion, is this a valid strong method of repair, or should I book some time at my friend's shop and plan on cutting the frame open?

One of our vendors here sells threaded washer/nut plug /bung things. Same as a nutsert but welded.

I'd consider using that for the transmission crossmember.

A rivnut that size should have no problem holding the weight/torque of the drivetrain.

I used rivnuts in my MJ for the floor and some aluminum ones for holding down the fuel pump assembly in my aluminum cell when I was using it.

to clarify it's not a transmission crossmember hole that has a problem (all of those bolts actually came out no problem,) it's the similar holes to which the transfer case skid bolts (one in the frame, and one into the xmission crossmember.)

I'm thinking it should be OK, just need to get under there and grind the old bolt heads off. I'm trying to get all the under-car hardware freed up little by little so that when I go to redo the suspension I won't have to fight too much with everything. I'm thinking the skid will have to come off as if I boost it I'll either need to install a transfer case drop or SYE, so I might as well address it now.

Rivnuts (nutserts) are used by auto and aircraft industries by the millions. If installed right, they are very effective. My Jeep's transfer case skidplate and forward leaf spring mounts are secured with 3/8" rivnuts

For rivnuts 1/4" and smaller, a tool, similar to a pop-riveter, is used.
http://www.ebay.com/itm/like/120930463797?lpid=82
For 3/8" rivnuts, I use a DIY tool.
http://www.jeepinwv.com/forum/viewt...d=62b9fcc0851a7a60bbf66b52f1f41bb3&view=print

Yeah they work well. My skids plates are held on by them, although I run them on the side of the frame rail instead of the bottom.

There's a method of using 5 washers between the rivnut & bolt, putting oil between the washers, and holding the washer stack with visegrips. I tried it and the rivnut would spin in the hole until I put a split lockwasher between the rivnut and washer stack. The split washer is installed opposite conventional way and keeps the rivnut from spinning. Works great for me and the rivnuts are tight, no spinning whatsoever.

nice, I will have to remember that, I still haven't had a chance to steal any lift time yet so your message is very timely! I do have a 33/64 drill bit so I will try that first. (got a lot of S&D drill bits when I was told to "dispose of" a big shelving unit full of old disused tools at a former job)

offroadordnance said:

There's a method of using 5 washers between the rivnut & bolt, putting oil between the washers, and holding the washer stack with visegrips. I tried it and the rivnut would spin in the hole until I put a split lockwasher between the rivnut and washer stack. The split washer is installed opposite conventional way and keeps the rivnut from spinning. Works great for me and the rivnuts are tight, no spinning whatsoever.

Click to expand...

what he said, except I use a star washer and lube it with synthetic caliper grease (mainly because I have tons of it laying around).

This worked like a charm for me when I tried it:

http://www.carolinarovers.info/croc-stuff/tips/259-make-your-own-rivnut-tool