Here are some shots of the rivNut:

 

Cebby - the welded on stud also sounds like a great idea. Would welding reduce the strength of the bolt, ie make it harder and more brittle?

 

mt_goat - the chassis metal looks pretty thick. I'd be surprised if a carriage bolt could bend the frame, but it sounds like it's happend to you. I don't think it will be an option for me because I don't see any way of getting above the chassis. Thanks for the suggestion...

 

There is something similar to the Rivnuts that doesn't need a special tool. That was what Superlift was sending out with their kits at one time. You drill the hole out to just the right size and slide it in (tight fit if I remember) and as you tighten down the bolt it sets itself in the hole and gets a better grip the more you tighten.

 

mt_goat - if you come across the nut you referred to, please let me know. Is it a blind installation? In other words, do you need to have access to both sides or just one side?

 

Here's another interesting option using a self tapping insert. No special tool is required.

 

Here's a larger shot of the self tapping insert from another company:

http://www.carrlane.com/Catalog/inde...3C3B285356445B

 

Just the one side. It may be the samething as the "well nut" Roger mentioned.

I can't see the self tapping insert working here because there isn't enough thickness to the frame for the threads to hold. Now if you were to weld a 3/8 inch-thick plate to the bottom of the frame (on both sides to keep it even) then you would have enough meat for the threads on the insert to hold. For that matter you could just drill and tap the plate.

 

Something like the Jack nuts here: http://www.auveco.com/proddetjack.htm

 

I looked at my Superlift instrutions, they called they nutserts. Here are some: http://www.aboveboardelectronics.com...nd/nutsert.htm

 

I was just going to say that this might be your best bet. If you can get to it.

 

Here's an interesting one, sqrsert.
http://www.avdel.textron.com/index.h...ed/sqrsert.htm

You just have to find a square drill bit for them

Go to a good autobody shop, they have all kinds of special tricks for repairing stuff.

 

mt_goat - thanks for all your input and the links. This thread may be useful for others who have a similar challenge. For the time being, I've managed to worm a straightened out coat hanger wire from the hole to a larger hole about a foot away. It seems that some holes closer to my target hole which would be large enough to fit either a nut/bolt through, were all blocked by internal partitions.

I'm going to attach nylon fishing line to the hanger wire and pull it through with a bolt fixed to the other end of the line. If this works, I'll be able to fasten the bolt with a nut and it'll be done. I may even have the bolt welded in place. My limited understanding of high heat applied to bolts is that it may reduce the tensile/shear strength of the bolt. Just gotta look for that fishing line now....

 

Well, the fishing line idea didn't work for me. The bolt got lodged somewhere in the chassis and trying to pull it out from either end didn't help. Lost a perfectly good 10.9 strength metric bolt!! Back to the drawing board.

 

Roger has some nuts with tabs welded on them that he sells with his body lift kits. http://www.4crawler.com/4x4/ForSale/ProductLine.shtml

Maybe you could fish one of those into place. Once in place the tab stops the nut from turning while you tighten the bolt. Very handy while installing a bodylift where you can't get a wrench on the nuts.

You are right, welding bolts will weaken them. It destroys the heat treatment. Should be ok with nuts though.

 

I've given up on the idea of fishing a nut/bolt in place. The last one got lodged somewhere in the chassis frame.

 

Drilled out the shackle with a 1/2" bit and I'll drive a lag bolt or equivalent into the chassis today. Hope this works.

 

Couldn't find a lag bolt for the 1/2" hole on a Saturday. Went back and decided to enlarge a nearby hole to try fishing through another bolt. This time....

SUCCESS!!! I used a couple of flange nuts with serated bottoms to make sure they don't come loose.

Here are the pics: