Rear seatbelt install problem

[riderdan]

Like a bad penny, I'm back with another question.

I got the rear seat belts installed this evening, but ran into a little problem that I can't seem to solve...

On the passenger side, where the seat belt latch mounts to the tunnel, I can't get the bolt to tighten. It's just spinning. Looking underneath, it looks to me like there's a threaded section that's spinning when I turn the bolt. It's almost impossible to reach, and it's threaded on the outside, so there's no way to grab it with a wrench.

My guess is that this is a piece that's installed in the trucks during assembly, as the seat belt install MWO doesn't mention installing this--it just shows the seat belt latch section, washer, and bolt.

Any advice on this one?

 

[BLK HMMWV]

It has probably come loose as you suggest. There is a backing plate that gets riveted to the underside of the body. it has a captive nut on it. yours isn't so captive it would seem. you can replace the backing plate or try and stake it and keep the nut from moving.

 

[911joeblow]

You might have to drill it out and put in a new nutsert.

 

[riderdan]

Thanks for the info.

That's what I was afraid of. I don't think I can get to the inside of the tunnel without major disassembly--the frame runs right by there and there's about 1/4 inch of space between the frame and tunnel. It might have been possible to get the end of a wrench in there (barely) but if I have to actually have access to that area, it might be a body-off-frame deal.

I thought about a tack weld, but it's also about 2 inches from the gas tank and I'm not sure I could get the tip of my MIG welder in there anyway.

 

[jkupka]

If you can drill it out, is it possible to use a longer bolt and just use a lock nut? Same principle...

 

[Stonewall]

With the nut spinning, drilling it out may be problematic. Perhaps drilling a hole right next to the existing and using a rivnut as suggested above.

 

[riderdan]

Oh, rivnuts! (That's a swear word, for sure)

Guess a rivnut tool and set of inserts is on my list. I seem to vaguely recall someone saying buying the truck was only the beginning. Just a few more thousand to spend until it's set up to my satisfaction.

 

[riderdan]

With the nut spinning, drilling it out may be problematic. Perhaps drilling a hole right next to the existing and using a rivnut as suggested above.

I think if I cut off the bolt (grab it with pliers and hacksaw off the head) the nut will just fall out. I hope.

 

[911joeblow]

Wait, you could try to use a rivnut tool to reseat the rivnut again! It is worth a try.

 

[Wire Fox]

Oh, rivnuts! (That's a swear word, for sure)

Guess a rivnut tool and set of inserts is on my list. I seem to vaguely recall someone saying buying the truck was only the beginning. Just a few more thousand to spend until it's set up to my satisfaction.

I'd recommend hitting up your local Menards, Harbor Freight, or whatever hardware store you have near you that carries a wide variety of tools. You can get a hand Rivnut/Nutsert/Threaded Nut Insert tool for under $15.

Wait, you could try to use a rivnut tool to reseat the rivnut again! It is worth a try.

That's such a brilliant idea that I never thought of. The tool works by just threading into the rivet nut and pulling those threads toward the surface to force the outer shell to expand, so there's not a lot of reason why you can't just thread in again and try to expand the existing rivnut just a tiny bit to cause it to seal once more. Fortunately for me, I haven't had to replace any Rivnut except for where they were actually missing, but I'm going to keep this in my mental toolbox of fast repairs.

 

[Stonewall]

One thing I thought of is that is a pretty large bolt for a hand rivnut tool. Might find it difficult to find a tool that will go that large.

 

[riderdan]

Yeah, I was just at Fastenall and they didn't have a rivnut that large. On top of that, I'm pretty sure the HF tool doesn't go anywhere near that big. And I couldn't get the tool on the rivnut with the bolt still through it, in any case.

I'm going to try and get a wrench up in there again, once I cut the bolt off and see if I can't finagle a locking nut onto a new bolt. It's a really tight squeeze though--maybe 1/2" tops, so it will be tricky. Plus, it's just at the end of what I can reach with a standard length wrench--so it might take purchasing a longer one. I might also need to look into some other single-side fasteners and see what can be done.

If anyone else has an idea, feel free to chime in.

 

[Lawdog734]

Is there enough room to have someone tack it with a tig welder so that you can get the bolt out properly, or is there no room for that?

 

[riderdan]

Is there enough room to have someone tack it with a tig welder so that you can get the bolt out properly, or is there no room for that?

Nope. From the underside, I can hardly reach it with a wrench, so there's no way to get the end of a TIG up in there. It's just too narrow and too far up. From the top, that big washer is in the way. Good idea though--that was my initial thought: take it over to the college's auto restoration sheet metal lab and use one of the TIG welders to spot weld the rivnut just enough to get the bolt out.

I thought about trying to re-set the rivnut as suggested above, but to get the tool in I have to get the bolt out. To get the bolt out, I have to have the rivnut tight. Chicken and egg

I'll think about it a little more, but I'm guessing a hacksaw and vise grips is in my future.

 

[daniel.7575]

Where the stuck bolt is located you could try jamming a thin chisel or screwdriver behind the seat belt tab effectively pulling the rivnut towards you at the same time as undoing the bolt.. If you can spray some release spray on the thread end of the bolt. If this fails to work then cut everything off flush with a grinder and 1mm cutting disc, sand/grind the rivnut as flush as possible then knock it inwards with a punch.. Replacing the rivnut after.. If you end up with a hole too large for a rivnut to bite into you could mount one in a plate and install as you do for the front seat belts..

 

[riderdan]

Where the stuck bolt is located you could try jamming a thin chisel or screwdriver behind the seat belt tab effectively pulling the rivnut towards you at the same time as undoing the bolt.. If you can spray some release spray on the thread end of the bolt. If this fails to work then cut everything off flush with a grinder and 1mm cutting disc, sand/grind the rivnut as flush as possible then knock it inwards with a punch.. Replacing the rivnut after.. If you end up with a hole too large for a rivnut to bite into you could mount one in a plate and install as you do for the front seat belts..

Good idea about the chisel. I'll try that tonight.

 

[infidel got me]

Oh, rivnuts! (That's a swear word, for sure)

Guess a rivnut tool and set of inserts is on my list. I seem to vaguely recall someone saying buying the truck was only the beginning. Just a few more thousand to spend until it's set up to my satisfaction.

How can you own a Humvee and not own a rivnut tool. I'm very disappointed!!!! lol just kidding

 

[riderdan]

How can you own a Humvee and not own a rivnut tool. I'm very disappointed!!!! lol just kidding

Well, I've got one on order now. Not that I'll need it for this particular job, but I expect to need it again--maybe soon.

 

[Action]

Do you trust your passengers safety to a rivnut?

 

[riderdan]

Do you trust your passengers safety to a rivnut?

I could be mistaken, but I think that's how the seatbelts were installed originally. At least the TM doesn't show installing the rivnuts in order to bolt the seat belts down... And rivnuts are safe enough for aircraft use.

At the size we're talking (7/16x20) I think they're sufficient. However, I'm probably not going to be able to get another one in that hole... which means I might have to cut out a section of tunnel, tig an aluminum nut/washer on the inside, and then tig the whole thing back together. Or it may mean taking the body off, because that's awful close to the fuel tank.

Of course, when I was first driving these, there were no seatbelts in the back. Usually the officer I was driving around chose to ride in the front, I suspect partly because of that.