55.2-59 Parts assist (rivetnut/plusnut)

[FAKKY]

Hey guys
Need a couple of rivetnut or plusnut in 7/16-20 size.
Having a hell of a time finding them online or locally.

If I cant find that - then a seatbelt shoulder bolt in a M10 size.


Any links - appreciated.

[mongocanfly]

Dont know if I've ever seen a 7/16 rivnut...but my kit has 10mm in it..
What are you using them on?

[FAKKY]

I've got a kit that does up to 1/2-13

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

But I need 7/16-20 for the shoulder seatbelt. I used a ~1/4 aluminium plate behind the sheetmetal drilled and tapped for 7/16-20 shoulder bolt. But on passenger side I retapped and think I stuffed it up doing that.

I can drill out and retap to a larger bolt - but then I will lose the rotation of the seatbelt on that shoulder. Not the end of the world ..... but a backup plan.

[G&R's57GMC]

I wouldn't trust a riv-nut for a safety item .

You need to weld a nut to a backer plate and put that inside the panel .

Ya I know , more work . But when your health depends on that belt it's worth doing it right . After all the life you save may be your own .

[mr48chev]

If it is for a seat belt mount I am another one who wouldn't trust a riv nut though sheet metal.

I've seen seats and seat belts that were pulled out of the floor of cars because they only had a small washer behind the nut on the bottom side and no backer plate.

[FAKKY]

Originally Posted by G&R's57GMC

I wouldn't trust a riv-nut for a safety item .

You need to weld a nut to a backer plate and put that inside the panel .

Ya I know , more work . But when your health depends on that belt it's worth doing it right . After all the life you save may be your own .

Not sure how to fit a nut on the backing plate and get it in there without cutting holes in the sheet metal.

Good thread here on strength.

https://www.garagejournal.com/forum/...d.php?t=413169

another ref point about 8 mins into video.

https://www.youtube.com/watch?v=0gGNq2zat6I


Finally - this would be shear strength in an accident. Your still grounded to seat by lap belt.

[FAKKY]

Originally Posted by mr48chev

If it is for a seat belt mount I am another one who wouldn't trust a riv nut though sheet metal.

I've seen seats and seat belts that were pulled out of the floor of cars because they only had a small washer behind the nut on the bottom side and no backer plate.

Its a ~1/4" aluminium plate threaded behind the sheet metal.

Pic here.

[jweb]

You really need a strong steel plate for the shoulder harness. Here's a step by step installing the Juliano's seat belts in a '56
http://bobshotrods.com/howto/3-point...chevy-pick-up/

[FAKKY]

Originally Posted by jweb

You really need a strong steel plate for the shoulder harness. Here's a step by step installing the Juliano's seat belts in a '56
http://bobshotrods.com/howto/3-point...chevy-pick-up/

Pretty much what was done.
Instead of 1/8th steel used closer to 1/4 aluminium.

https://www.hobson.com.au/files/tech...apped-hole.pdf

[jweb]

Originally Posted by FAKKY

Pretty much what was done.
Instead of 1/8th steel used closer to 1/4 aluminium.

https://www.hobson.com.au/files/tech...apped-hole.pdf

I'm sure your 1/4" aluminum will be fine. How difficult would it be to just replace the aluminum backer you made?

[FAKKY]

Originally Posted by jweb

I'm sure your 1/4" aluminum will be fine. How difficult would it be to just replace the aluminum backer you made?

Its kind of pain ..... I think each one took me about 2 hours
But .... might be a good option too.

[G&R's57GMC]

Originally Posted by FAKKY

Not sure how to fit a nut on the backing plate and get it in there without cutting holes in the sheet metal.

Finally - this would be shear strength in an accident. Your still grounded to seat by lap belt.

Uh ... NO the seat belt portion is reliant on the shoulder belt portion as it's the 3rd mounting point of the "System" without it the lap belt portion is disabled .

In other words "Hello dash and windshield" when Any part of the mount "system" fails !

So what's a few hours now compared to injury or death later ?!

BTW I wouldn't trust the threads in the aluminum , not enough material for the thread to grab . A proper thread depth would be 9/16" in steel nut on a 1/8" steel backer 3" long or wide behind a steel panel the has been welded at least that long to adjoining panels .

[FAKKY]

Originally Posted by G&R's57GMC

Uh ... NO the seat belt portion is reliant on the shoulder belt portion as it's the 3rd mounting point of the "System" without it the lap belt portion is disabled .

In other words "Hello dash and windshield" when Any part of the mount "system" fails !

So what's a few hours now compared to injury or death later ?!

BTW I wouldn't trust the threads in the aluminum , not enough material for the thread to grab . A proper thread depth would be 9/16" in steel nut on a 1/8" steel backer 3" long or wide behind a steel panel the has been welded at least that long to adjoining panels .

Easy Theres plenty of time for you over at the HAMB.
This thread was simply about finding 7/16-20 rivets.

I already have in back of my mind a number of alternatives including re-doing. I havent seen a single seatbelt install talk about what you mention including all the referenced videos/links above from manufacturers.

[mr48chev]

It'd fine to look for rivnuts if you use them properly. Smart A_ _ comments to someone who is concerned about your safety really don't help.

A rivnut in 16 gage sheet metal isn't going to have the holding power against a direct pull that a nut affixed to a plate will or a proper thickness steel plate.

A 1/4 inch piece of aluminum doesn't have the holding power in the threads and a bolt might pull out in a hard impact.

I got rear ended by a garebage truck in my 92 Geo Prism GSI a few years back and the first impact broke the seat back and when he drove me into a Johnson barrier the second impact put a bruise on my left shoulder that lasted almost three months. My chest didn't hit the steering wheel nor did my head hit the windshield. Smashed at both ends all four doors would still open and close. That impressed the state partrolman and a couple of others. I figure he was doing 40 when he hit me. As hard as I hit that shoulder belt any suspect fastener would have given away.

[FAKKY]

Originally Posted by mr48chev

It'd fine to look for rivnuts if you use them properly. Smart A_ _ comments to someone who is concerned about your safety really don't help.

A rivnut in 16 gage sheet metal isn't going to have the holding power against a direct pull that a nut affixed to a plate will or a proper thickness steel plate.

A 1/4 inch piece of aluminum doesn't have the holding power in the threads and a bolt might pull out in a hard impact.

I got rear ended by a garebage truck in my 92 Geo Prism GSI a few years back and the first impact broke the seat back and when he drove me into a Johnson barrier the second impact put a bruise on my left shoulder that lasted almost three months. My chest didn't hit the steering wheel nor did my head hit the windshield. Smashed at both ends all four doors would still open and close. That impressed the state partrolman and a couple of others. I figure he was doing 40 when he hit me. As hard as I hit that shoulder belt any suspect fastener would have given away.

Not sure who the top part was direct at
I posted a number of threads including scientific data and manafacturer recommendations.
Not planning on installing a rivet to JUST sheetmetal. It would be a rivet going through sheetmetal and then through 1/4" aluminium.

As regard to the aluminium versus steel. Most of the seatbelt shoulder plates you see are areound 1/8. Im using 1/4 aluminium. If you loko at the the sheer strength graphs I sent in thre thread - you only need a 50% increase in use of aluminioum to be equal in thread sheer strrength to steel.

1/8 ″ 3.175 mm
1/4 ″ 6.35 mm

So roughly - threads on 3.175 * 150% ~ 4.625mm is rough equivalent strength foir thread sheer. So honestly I think Im fine. As I also mentioned - not planning to NOT do anyting and leave it damaged ..... a plusnut in 7/16 size would have over 2000lbs shear strength given a 3/8 is 1675.

You can read that here.

http://www.rivet-nut.com/assets/rivn...properties.pdf


Long story short - was just looking to see if they made them. Since they seem to but its more of a speciality item Ill consider a helicoil insert or just redoing it

[dsraven]

well, whatever you end up doing, it is your head and your dash/steering wheel. you decide.
if you stick with the aluminum plate back there also consider the electrolysis between the dissimilar metals and how they corrode because of that. manufacturers use a plastic sheet between dissimilar metals to slow the process down. you may consider replacing the aluminum with steel for that reason alone. if thats the case you could possibly install a steel plate with the welded nut on it. somebody on here has done that but I don't remember who.
anybody

[dsraven]

found it, has pics too

https://67-72chevytrucks.com/vboard/...d.php?t=799565

[dsraven]

another one. hope that helps

http://67-72chevytrucks.com/vboard/s...d.php?t=416856

[nvrdone]

when we put the 3 point belts in my '49 we used 3/16" steel plate with a nut welded to the back side. I think the plate was about 3 x 4" then drilled and tapped 1 hole on opposite corners. fed the plate down inside the rear panel on a piece of fish line. threaded bolts into the threaded holes until we could get the plate plug welded in. I hope its strong enough to hold me in, but i hope i never have to find out

[FAKKY]

Originally Posted by nvrdone

when we put the 3 point belts in my '49 we used 3/16" steel plate with a nut welded to the back side. I think the plate was about 3 x 4" then drilled and tapped 1 hole on opposite corners. fed the plate down inside the rear panel on a piece of fish line. threaded bolts into the threaded holes until we could get the plate plug welded in. I hope its strong enough to hold me in, but i hope i never have to find out

Thx - pretty much what I did on this one minus the welding

Think I'll probably end up pulling it out and re-doing over ....... I;ll use steel to make everyone happy

Would have been fine with a plusnut ...... but they dont make in that size thread best I can tell.

[FAKKY]

Originally Posted by dsraven

another one. hope that helps

http://67-72chevytrucks.com/vboard/s...d.php?t=416856

thanks man

[1project2many]

This thread was simply about finding 7/16-20 rivets.

Yep... frustrating when folks decide to start advising on your choices rather than answering simple questions. But years ago a friend of mine was nearly killed because the car he'd been building by hand damn near exploded on the highway when his homemade driveshaft came apart and ripped into the fuel tank. I had unvoiced concerns about his design and I decided to speak up from that point on if I had concerns.


7/16" thread isn't common outside the automotive world. We use belts and fasteners that are added after the vehicle is built and in almost all applications they use 7/16"-20 thread to attach the belt to the brackets / bases. Folks here might be surprised to find 1,000lb wheelchairs are secured with these belts via a track system. Tracks are attached to a plywood floor or a wall with 5/16" trailer decking screws placed every 4" in the track. It doesn't seem secure but I understand the manufacturers do crash testing and the dummies live through the crash (umm... that's the crash test dummies, not the manufacturers). The tracks are similar to the "Euro adjuster" in one of the links posted by DSRaven.

7/16" thread fastener isn't a common size. It's most mostly used in the automotive world. Fastenal has a link to Rivnut products and it looks like they don't have a 7/16" rivnut listed. https://www.swfastener.com/pdf/RIVNU...inalRivnut.pdf

Are you committed to using the 7/16" fastener in the block of aluminum?

[mr48chev]

We are advising him because we have seen too many people do unsafe things in an effort to cut corners time wise or cut corners cost wise.

I'm alive today because the shoulder harnesses in both helicopters I went through crashes in were proper belts and were installed correctly. I'd be pretty well busted up yet if that shoulder harness in the Prism GSI hadn't held when the truck shoved me into the barrier.

Most of those seat belt mounting plates that are 1/8 have a nut affixed to that 1/8 plate. The 1/8 piece is to spread the pull over a wider area.

Yes the original post was about a rivnut that rivnut intended to hold the bolt from a shoulder harness. There was no mention of a backer plate in that original post. That lead several of us to believe that his intent was to drill a hole, stick the rivnut in with no backer and clamp it down so it looked like he had functioning shoulder harnesses in it.

I've got box of Rivnuts out in the garage that are used to mount things that won't have a direct pull on an impact like tail light brackets or other non stress items.

It's still comes down to make things as absolutely safe and functionally safe as you can and not to just appear safe. If you are going to install shoulder harnesses (often at the behest of someone's wife) they need to be installed correctly so they actually will work.

[FAKKY]

Originally Posted by 1project2many

Yep... frustrating when folks decide to start advising on your choices rather than answering simple questions. But years ago a friend of mine was nearly killed because the car he'd been building by hand damn near exploded on the highway when his homemade driveshaft came apart and ripped into the fuel tank. I had unvoiced concerns about his design and I decided to speak up from that point on if I had concerns.


7/16" thread isn't common outside the automotive world. We use belts and fasteners that are added after the vehicle is built and in almost all applications they use 7/16"-20 thread to attach the belt to the brackets / bases. Folks here might be surprised to find 1,000lb wheelchairs are secured with these belts via a track system. Tracks are attached to a plywood floor or a wall with 5/16" trailer decking screws placed every 4" in the track. It doesn't seem secure but I understand the manufacturers do crash testing and the dummies live through the crash (umm... that's the crash test dummies, not the manufacturers). The tracks are similar to the "Euro adjuster" in one of the links posted by DSRaven.

7/16" thread fastener isn't a common size. It's most mostly used in the automotive world. Fastenal has a link to Rivnut products and it looks like they don't have a 7/16" rivnut listed. https://www.swfastener.com/pdf/RIVNU...inalRivnut.pdf

Are you committed to using the 7/16" fastener in the block of aluminum?

Sorry been tied up.
Yep a bit frustrating - I dont mind some advice from everyone as people have more experience than me. At same time I wasnt really worried about the bolt pulling through. I'd be more worried about ripping the sheet metal now that there are 3 holes in it to secure the seatbelt shoulder bolt. But anyway - since I had to pull one side out with no 7/16 rivent I went along and redid both sides with overkill



Im still not worried about the threads ........

Appreciate the info on the 7/16 - its what I foudn also - just weird given they make them in larger sizes ......

[FAKKY]

Originally Posted by mr48chev

We are advising him because we have seen too many people do unsafe things in an effort to cut corners time wise or cut corners cost wise.

Nope I appreciate that. I know the intent was good you've helped me out on more than 1 or 10 occassions. I was just frustrated as turned into a bit of stuff I hit a lot in forums saying it cant be done. I didnt mentioned the 3/8 | 1/4" aluminium as backing as it wasnt the reason for my thread .... I had done the research and was comfortable with it. I think there are way to many geometries going on that none of us really know - the idea it will pull out even based on data I looked out is a best guess effort. Like I said Im 200% more concerned the sheet metal will tear/shear than the threads of either of setups

But anyway - moving on - we determined that 7/16 doesnt exist for a rivnut
And I do feel better having the steel (about same 3/8 or 1/4) and nut now behind the pillar .... except for that 1mm thick sheetmetal