no Welding Solution for broken frame bolts

[FiNorman]

I was removing several of the bolts that hold my shackle hangers and steering bracket and unfortunately I broke off several of the bolts. The nut that fits these bolts is placed inside of the frame at the factory.
The previous solutions I found were to cut a hole into the frame big enough either weld the nut onto the bottom of the hole, or hold it manually until you tighten your bolt, then weld the frame back together.
It took me 15 minutes to fix this problem (after working on the solution for 3 days). Please feel free to critique this method, let me know if there is anything that I am missing or unsafe/unusable. And if this has been used/posted by others please forgive my plagiarism.

I first started fishing out the old broken bolt inside of the frame by using a coat hanger and magnet through the holes in the frame.
My next step was to flip over a 7/16ths (please check to make sure that your new flange nut is 7/16ths 14 thread, ask me how I know) flange nut so that the flange is away from the frame, on top of the hole. Center the nut so that the hex is covering the hole and sharpie marker the hex design onto the top of the hole.

 

[FiNorman]

Next I used This tool from Harbor Freight (less than $20 I think) or a Dremel and etched out the hex shape in frame. I found that its actually better to leave some edges somewhat sharp and unfinished, but I did file it down to help accommodate a good fit.

I then took a 4inch 7/16ths (again by 14 thread... ask me how I know) and threaded the flange nut partially, with the flange portion toward the head of the bolt.
I then used a hammer to tap the nut into the hole creating that tight fit where it will sit.

 

[FiNorman]

next I took the flange nut, placed it on a string and pushed it with a wire through a larger hole in the frame to a location over the hole, keeping the flange portion of the nut towards the top of the frame and away from the hole.
I then used my 4 inch bolt to lift up the nut, now over the hex hole and push it up until the 4 inch bolt pinched the nut into the top of the frame. The Flange will bit down on the top of the frame as you thread it slightly.
once you have it secure, now pull the nut down to the hole, thread it more manually so it is securely on the bolt and pull the hex nut down to the hex cut out until it is securely through the hole.
I think at this point you can either weld the nut through the hole, or maybe even epoxy it to the frame, to keep it secure since the nut is now held in place by a hex hole in the frame.
grind it down, I ran a ream through mine to insure the welding didn't damage the threads and enjoy.
I hope this helps someone as it was killing me to find a solution.

 

[IOPort51]

Briliant!!

 

[FiNorman]

One of the things that my son and I love about working on the cj is the payoff that comes from thinking over a problem, trying different approaches and sometimes coming up with a solution.

 

[WSS]

Super slick! That can solve a few other problem areas too. Thanks for the detailed write up. Pics are awesome.

 

[Gunner Actual]

I did pretty much the same thing on some body mounts

 

[FiNorman]

I have just a couple of follow up points. My father in law (mechanical engineer and all around good guy) also had a great suggestion. Since many of you will be doing this upside down without being able to turn the frame over so the downside is up, you may find it easier to put a large slab of axle grease on the tip of your bolt as you go through your new "hex hole" into your the upside down hex night. This large glob of grease will stick to the nut and allow you to balance it while you lift it up until the flange hits the top of your frame rail, then apply pressure and turn to get the thread started. (Sort of like Saving Private Ryan when they used their socks and axle grease to make "sticky bombs").

The next repair I did I used an epoxy called JB Weld.... I mixed it up put it on a cotton swab, stuck it through the hole to the upside down flange nut, then pulled it through the hole. I let is sit over night then took a grinder to shave off the 1/8 of an inch that was sticking up from the rail to make it flush... the bolt didn't move a bit.
Happy Memorial Day to you all.

 

[Jimbos76cj]

My only concern is that the flange that makes contact with the inside of the frame is considerably smaller then the nut and its also thinner then the nut.

Sorry.. I have 2 concerns. Unless you specially order grade 8.. Which they should be off the shelf flange nuts are normally low carbon steel. Which means its alot weaker then grade 8. It would be a great idea for nuts that don't have alot of force placed on em but for ones that hold your suspension on I'd go with grade 8 nut welded from the inside..

Oh.. 3rd concern. The hex holes you cut into the frame have some sharp points to em.. They could be a place for cracks to start.

I don't have a fourth thought.. Yet!

 

[jdarg]

It looks unsafe IMHO. Steering and suspension mounting points are not areas where hillbilly rigging is viable. You have a welder...weld a DOM sleeve in there and it will be better than stock.

There's no way that nut is even grade 5.

And why would you even suggest epoxying anything to do with steering or suspension attaching points?

 

[FiNorman]

It looks unsafe IMHO. Steering and suspension mounting points are not areas where hillbilly rigging is viable. You have a welder...weld a DOM sleeve in there and it will be better than stock.

There's no way that nut is even grade 5.

And why would you even suggest epoxying anything to do with steering or suspension attaching points?

I don't think you understood the process.

 

[Jimbos76cj]

I don't think you understood the process.

I under stand the process and think its a bad idea.. I listed the reasons in my reply on the first page.. Those nuts are no where near as strong as they should be... Plus its not the whole body of that nut holding the bracket on its just that thin weak shoulder on it.

I work for a fastener company for several years sourcing, testing and inspecting nuts and bolts and I learned a great deal while doing it. I can promise you that the quality of a grade 8 bolt from HD and the quality of a grade 8 bolt from a company like fastenal are alot different. I inspected product for several local attractions that have very large, high speed roller coasters cough sneeze Disney, universal Islands of adventure cough hack. That nut that you used unless special ordered is low carbon.. less then grade five, If it were grade 8 it would not have that chrome finish to it unless you it specially plated or paid a ton of money for em.

I would remove it and weld in a good grade 8 nut to the inside of the frame.

How ever that is my .02

Oh I have had to same day order 600 1/2- 20 x 6" long bolts from wisconsin to get an attraction back up and running after a crack was found in the body of a bolt. Any guess on how much that costs??

 

[IOPort51]

I am not trying to pour gas on this discussion but If you weld a grade 8 nut does it affect the temper and strength of that nut?? As in it is not a grade 8 anymore??

This seemed like a clever idea and more than likely is, just not for this specific purpose. After giving this thought I think I would go another way and avoid welding completely. I am thinking drill through both sides, drill one side over size to insert the spacer into the frame and use a pipe spacer to handle the compression on the frame. bolt all the way through.

the flange nut may be handy some where else, just not on the spring hanger or the steering box.

 

[Jimbos76cj]

Yes.. Welding a grade 8 will weaken it a little bit.. Truly it's not the strength that become a problem but the brittleness of it. How ever any cutting, welding, heating bending changes the strength of the item your working on. Well at most of us jeep guy levels of welding.. Now lets get to the problem at hand.. The contact area of that flange nut is very, very small and very thin. Grade 8 has a tensil strength around 150000 pounds.. Do you think you will ever put enough of a load on a grade 8 nut or bolt to cause an issue with it? Most of those bolts that get removed are rusty.. Bet that takes a lot of the strength out of em.

After checking my trusty fastenal site and going with he used a half inch nut across the corners using the min measurement is .840 the max diameter across the flange is 1.03 after a little fancy math that means the corners only have a contact patch with the frame of .095.

Lets look at the same for the flats. The min width across the flats is .736 and with a max of 1.03 flange your looking at a contact area max of .147 right in the middle of the nut and that gets progressively smaller the close you get to the corners

Now lets look at the thickness of the nut. If it has a max thickness over all of .437 and a wrenching length of .31 that means the flange is only .147 thick were it makes contact with the side of the nut and gets thinner as it slopes off to a thickness of .05

http://www.fastenal.com/content/product_specifications/HFN.SER.Z.pdf

That's if it's a 1/2 inch nut.. If its smaller then all those measurements become dramatically less. And this numbers are only valid assuming he cut the hex holes in the frame to exactly the perfect size for the nut to fit. If its .01-.03 off you looking at a contact area about .100

Like I said in my original post it's not so much the strength of the nut as it is the amount and thickness of the flange.

 

[73CJ]

I am not trying to pour gas on this discussion but If you weld a grade 8 nut does it affect the temper and strength of that nut?? As in it is not a grade 8 anymore??D

Never a good idea to weld on a Grade 8 anything. Hydrogen embrittlement an occur and the fastener gets brittle. Most unsafe.

Hardened nuts should not be used with Grade 8 bolts in most applications. A certain amount of deformation of the nut is good. It forms to the surface of the hard bolt.

The epoxy really has nothing to do with strength of the joint. Bolt strength is needed to obtain clamp load. Friction between the parts being joined. As long as the epoxy holds the nut to a proper torque (equals clamp load) the joint should not fail. Even if the epoxy failed, it most likely would not be a catastrophic failure.

Has anyone mentioned nut plates? Works pretty good.

 

[jdarg]

I don't think you understood the process.

No, I think I do.

73CJs nut plate suggestion is good too. I wouldn't run an internal nut without one. The DOM sleeve w/ through bolts is going to be stronger though, since you are then clamping the load against two sides of the frame w/ a rigid member (the DOM sleeve) between them.

YJ's use nut plates on the front suspension/bumper/recovery hook bolt holes from the factory. IMHO its the bare minimum. I've seen YJ and TJ frames actually crack and tear in the tow hook area in heavy duty recovery attempts, using the backing plate setup. Your setup would fail much sooner under those conditions.