Hot Rods Any experience with nutserts?

Hello and happy holidays! I was told by a friend that I can drill holes in my frame and use nutserts to attach the body, then tack weld them for extra security. ('31 sedan with a floor structure that I built) I see people weld nuts in the frame for the same purpose, but I always worry about my welding skills and prefer to over-build for my own peace of mind. Another route I was thinking of going was putting holes in the top and bottom, weld a sleeve in there, and run a bolt straight through, but it's going to be a high boy, so I don't want to have nuts and bolts popping out of the bottom if I can avoid it. Has anyone had experience with the nutserts and whether or not that would work like I'm thinking it will?
Thanks in advance!

 

The only nutserts I have used was aluminum but U believe they also make some from steel so I would think you could tack them but I have never had any come loose.

As far as mounting the body I always drill a hole and bolt the body to the frame. HRP

 

I too have used them in aluminum and maybe steel, I've got an assortment and have used them other places but...to your question, I'd feel more comfortable with a welded nut....I am going to guess that you have a rectangular tube frame so you can't weld under the channel (as in a C channel frame). My 38 Chevy has body bolts through the frame (it's a "top hat" design and I have a bolt that runs all the way through with a nut and lock washer, in 45 years none of them have loosened or fallen off. Use a little Locktite if you you wear both a belt and suspenders

 

Yes, steel nutcerts are perfect for this. I install them then weld them.

 

I would assume the steel nutserts would work but they aren't very thick. I'd look I to getting weld in bungs from a place like Bung King and using those.

 

I built my own bung style design.

I'll post a couple pics tomorrow.

I used some actual 1/2" bolt concrete inserts. They are made to be epoxied into drilled holes in concrete.

They are kind of expensive but I liked the length and thickness of them. I then took some 1/8" thick strap and cut 3" long pieces. Took those and drilled a hole into the center of the strap just big enough that I could tap the insert into the hole and flush it out with the strap then a small tig Weld around the bottom side of the strap.

Next up I will drill holes in the frame and drop them in. I will weld the strap onto the frame. I plan on using something like 1/2" thick rubber for body mounts so the extra 1/8" height of the strap won't be much.

 

Nutserts and Rivnuts are available in aluminum and steel and if set with the proper tool and exact hole size as well as proper grip length really don’t require welding. Be aware that some tools designed to set nutserts and rivnuts will not work for both steel and aluminum however those designed for steel will set both. Nutserts and Rivnuts are commonly used in aircraft and aerospace applications and are very reliable.

 

I suck at putting in nut-serts. 4 different tools and about 1000 nut-serts sitting in my drawer. I said the same thing about applying urethane (extra thick and gooey) until I found the right caulk gun. Now it`s a smooth operation.

 

Use them a lot i use the steel ones mostly. I would weld them if you are going to use them for body mounts. Imo

 

I have nutserts holding up my fuel tank my head lite stands , been there 20+ years without a problem. As has been mentioned , a clean , precise hole is key to success . properly installed , in use , the stronger the " pull" the tighter they get . I wasn't convinced before I used them so I set up a test , twisted off a Gr 5 - 3/8-16 bolt without hurting the insert .

 

This is all very helpful, Thanks!!!!!!

 

I have used them in different places and they work great.

 

I faced the same dilemma since my frame is made of square tubing. I found this method in some magazine. Get some grade 8 flange nuts the size you need. Then take one of those stepped drill bits and drill into the frame just far enough that the flange nut will drop in the hole and set flush with the top of the frame, but not fall through. Weld around the perimeter of the flange nut. On a Model A it really doesn't matter if the weld is a little proud of the frame so I didn't grind off any of the weld.

I started by taking a cut off section of the tubing I made the frame with and welded in the nut. I then clamped the section in a vise and ran a bolt into the nut. I beat it with a sledge until I got a failure. I had to really beat on the bolt to get it to fail. The failure started at the tubing just outside the weld area. That was good enough for me.

 

The frame is boxed. I thought about this before I did so, but at the time I had no idea when the body would end up so I kicked the decision down the road.

 

I would not want to attach your body to your frame with nutserts. Its not that they won't do a decent job holding the body in place during normal driving, but I have my doubts about how effective they will be if you are involved in an accident. I have lots of rivet nuts on hand and use them for specific things......usually when its impossible to get to the backside of something. They work great for their designed purposes.

I would consider either tack welding round stock inside the frame rail, or some flat rectangular stock in each location. The rectangular stock can be a little more forgiving in placement because they can be longer. Then when you set your body on the frame, you can drill and tap exactly where the bolts need to be.

When you put your boxing plates in place...........(you are going to box the frame aren't you), if you are concerned about how your welds look, try doing a string of overlapping tack welds. Try it on some scrap. Often the the biggest problem with welds is incorrect wire speed/amp settings. Look on your welder for a chart or look on line for one, and set your welder to the correct setting. A lot of people just select "something" and if they get it to weld......thats what they use. Once you get a correct ballpark setting, have someone slightly move the amp setting up and then down to see how your weld changes. Then use the best setting. Also, don't tilt your gun too far sideways so you can see.....that lets the shielding gas escape. Try to stay reasonably vertical (70 degrees). People tend to change that angle as they move along. Lastly, try the overlapping tack weld method. It looks pretty decent and is very easy to do.

 

@jaracer , I did the exact same thing on my '33 Plymouth coupe for the front body mounts because I boxed the front of the frame. Works great! Come to think of it I did that on my '24 DB Roadster for all the body mounts as the frame is fully boxed.

Dave

 

Often whenusing nutserts, people are working with thin metal. When drilling thin metal with a two flute drill bit, it doesn't cut a round hole. Then when you install the nutsert it may fit loosely even though you used the correct size drill bit. Try buying a small reamer thats the correct size. Drill undersize and ream and you get a rounder hole because the reamer has more flutes. Punching holes instead of drilling them usually results in a more consistant hole size as well, but many locations are difficult to punch. You can also find three flute drill bits that help.

 

I use steel nutserts with the grooves along the sides. And also I put a bit of red locktite around the groove before setting them, in hopes that it will help keep them from spinning later on down the line. Not really sure if the loctite helps any, but I've had good success.

I agree with ekimneribo, you want a good fit with the nutsert and the hole. stepped drill bits/uni-bits work nicely for a good round hole.

And you also want to make sure that the nutsert you are using is in the thickness range of the material you're setting it into.

I use nutserts mostly for less critical things than say, holding on a pedal assembly, or motor/transmission mount, or something that needs to be very strong. Nutserts if sized and installed correctly can definitely be used for some heavier duty applications, one of my jeeps has the under belly skid plate (and transmission mount) held onto the frame with 6 large nutserts.

On my 33 Chevy I have my inside door skins held on with a bunch of small nutserts, as well as all of the body panels bolted into nutserts set into the steel structure (used to be wood structure, with wood screws)

 

If you have questions about your welding skills, then tacking in steel nutserts might become an issue also. Nutserts all have a very small flange at the top, so you need to be very careful tacking the edge and not getting into the nutsert opening also. I'd simply install the nutserts as designed, and call it good. I've used them for a very long time and never had a failure, or need to tack them in.
I would be sure to buy a good installation tool, as some are sketchy quality. Done with a high quality install tool, they should work well.

 

i have used them to hold the bed strips in my pickup.it depends what you expect them to do.i was considering using them to bolt a mirror to a door where there is a double panel with no access from the inside m5 threads

 

I used nutcerts in the rectangular tubing of my LSR roadster. I always used red lock-tite on the edge and the proper tool. They have never failed.

 

I have seen many boxed frames with small access slots where the body mounts go. Use a flanged frame nut and slide it in with a box end wrench, or tap a piece of 1/4" or 3/8" flat bar and slide it in. The flat bar can be left as is, or welded it in the slot. While there are heavy duty nutserts, many take a heavy duty tool to get the proper crush. I use them in thin sheet materials that I can get a good crush with a hand tool, but don't use them in thicker material. While I know it was done with hundreds, maybe thousands, of glass T buckets. please don't use the rubber bodied nutserts.

 

I wouldn’t feel comfortable using nurserts for anything structural. The flange nut method mentioned above is a good one I’ve used a few times.
If yo do use nutserts, I recommend steel for sure. The size of the hole you drill must be the correct size (not any larger) and the nutsert you use needs to have the appropriate length of crush area for the thickness of material you’re putting it in. You’ll also need to de-burr the inside of the hole you drill through the frame. I’d also assume you’d use 3/8” bolts which is a pretty big nutsert, so that’ll be fun too.

 

would also suggest sacrificing a few nutserts using a piece of metal the same thickness as what you're going to be using them on, put that piece of metal in a vice, drill a few holes and set a few nutserts. you'll feel when they get set, and you can look on the back side to see what they should look like once you feel them set nicely. Also, you can after the fact (on the front side) look at how close the threads are to the flush surface of the metal, and you can use that as a guide to judge the other nutserts that you set, when you don't have visibility on the back side.

Honestly though, after you set a few of them, it's not that bad. Especially if you have a decent setting tool. The hardest most frustrating way is using a nut/bolt and two wrenches. hard to keep everything straight that way. I use an Astro brand tool that you chuck into a drill. Once you get the clutch setting on your drill dialed in (by sacrificing a few nutserts, or by carefully setting the first one, sneaking up to the final clutch setting), then you really don't have to think about it, just keep the tool straight inline with the hole, and pull the trigger till the clutch engages.

 

they work great with the correct setting tool. 2 handles job, not the hardware store pliers type.

I only use them for light duty stuff, never structural or body mounting.

 

There are two types of metal nutcerts thin flange and thick flanged, use the thick flange for structural applications.

 

Nutserts are suprisingly strong. The tonneau cover in my daughter's ute (picture below) is held on with Lift-a-Dot fasteners. The tonneau tension and wind load had pulled the screw-in Lift-a-Dot fasteners out of the rear window panel. The panel is blind, so cannot get a nut in from underneath. I used nutserts, and have yet to have them budge.

Agree with the cautions above - buy a decent setting tool (I use the two-handle job) and practice on some scrap first. If you are hamfisted like me, its easy to over-crush the insert.


Cheers,
Harv

 

I’ve used a ton of em. But never for a body mount.
I’ll pass. I have welded flange nuts from the top.
I prefer welding 3/8 plugs into the frame. Then drilling and taping them.

 

Bumping this up, as progress being made here..... I have to box my A frame horns half way =in front of K member, about 3''. Thinking the 'certs..... This will have a load bearing somewhat=30lbs=radiator.
Now, with the boxing i'll be doing, I can still get a nut in behind there. I can STILL, and WILL, drill and tap my boxing plate to capture a good 3/16 of an inch, and use a fine thread, for more threads per inch. There will be (2) certs/nuts in each plate, and a crossbar to boot. Plus+ I'll be making mounts from the OG crossmember to tie it all in. It will all be removable.
My only concern= cert's stick "up", and I need them to be flush with my "boxing" plate.
I have heard there are different one's/methods. Different cert's= flush mount, etc.....
I could just weld nuts to the back of my plates before I burn them in for good.
Idea's? , thought's , real world knowledge? It will be overkill either way. This would be only in the safety factor, and not hackama bob stuff...........

 

Agreed. They are great for light duty stuff and I set a lot of them. But bumpers, body mounts, motor mounts, etc, I buy threaded steel bungs form the BungKing. Partly because of the name but they also chamfered around the top to make them ready to weld in. Little tp when welding bungs on a frame, thread a brass bolt in the hole to keep the threads clean.