Do rivet nuts work?

[Superhart]

I have a steel floor in my 1930 Model A Ford. At present the seats are held to the floor by bolts that go through the floor with a nut underneath the floor. Yes when I want to remove the seats, I need a second person with a wrench underneath the car to stabilize the nut while I remove the bolt from inside the car. Someone suggested an item called a “rivet nur“. This would supposedly eliminate the nut underneath the floor which can come loose. Does anyone have any knowledge of this item and how well it works? I have seen this item and it looks like it should work fairly well but since I have never used them, I am seeking opinion from the membership. The size that I would need to use is for a 1/4 inch bolt. Has anyone used this item? Comments would be appreciated.

[Brentwood Bob]

Similiar to a clinch nut?

[Merc Cruzer]

Yes, I have used them when installing PS on my 53' Merc, to fasten the end frame bracket to the car. They were used by the factory originally, for the same purpose. These are way heaver than you will be using, but the application is the same.

I have always been able to reach around to get both ends of the bolt and nut, when removing or installing the seat, but your reach might be more. It depends on how good the metal is on your floor and floor brace. If it is at all marginal, you could just rip out the nut when adjusting the seat. I use additional heavy large washers on the bottom,below the floor.

[LeonardS]

Occasionally a rivnut will spin when trying to remove a bolt. You then have a fun situation, trying to remove it. If you have access to the bottom side, then it’s not bad. If it’s in a cavity, then “Houston, we have a problem”!

[Tom Grz]

I’ve used them in a few applications and they work great. I just don’t know if they’re prone to loosening and spinning over time which could make it a hassle to remove the bolt.

[Oldbluoval]

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Leonard & Tom
They may have an application. But, always a but, they are very prone to spin.
I don’t use them….for anything.
Just imho …from experience

[BRENT in 10-uh-C]

Originally Posted by Superhart

I have a steel floor in my 1930 Model A Ford. At present the seats are held to the floor by bolts that go through the floor with a nut underneath the floor. Yes when I want to remove the seats, I need a second person with a wrench underneath the car to stabilize the nut while I remove the bolt from inside the car. Someone suggested an item called a “rivet nur“. This would supposedly eliminate the nut underneath the floor which can come loose. Does anyone have any knowledge of this item and how well it works? I have seen this item and it looks like it should work fairly well but since I have never used them, I am seeking opinion from the membership. The size that I would need to use is for a 1/4 inch bolt. Has anyone used this item? Comments would be appreciated.

Well, ...what you are asking is a loaded question IMO. They are handy however like others stated above, I have found they don't work as well with light-gauge sheetmetal uses for that reason. Where they shine IMO is in boxed tubing applications where you want to attach something like an electric fuel pump to a piece of tubing and don't want to fasten it with a thru bolt.

With that said, are you certain using ¼" bolts is/are strong enough for that application? -especially if light sheetmetal is used?? In your situation, maybe use some 0.250" wall flat bar (-maybe stainless that can be polished??) that can be threaded in each location of your seat bolts. Then use one or two long bolts to draw the flatbar up to the floor pan, and start threading in your regular length seat bolts. Once those correct length bolts are tight, remove the longer bolts and install the remaining correct length bolts. By doing this, the flat bar spreads the load over a greater area, ...especially in the event of an impact where the seats have a better chance of not ripping out of the floor pans.

[LeonardS]

Originally Posted by Oldbluoval

Leonard & Tom
They may have an application. But, always a but, they are very prone to spin.
I don’t use them….for anything.
Just imho …from experience

I think that’s what I said…..it’s trouble if they spin.

[Superhart]

To Brent, I had thought about using .25 x 1.5 steel bar underneath the cabin floor and tapping it to receive the seat bolts. I realize that using the flat bars would be very sturdy and also strengthen the floor. When I considered the cost of materials at nearly $100. In addition, I don’t always have an extra pair of hands available to help me. That’s why I considered going the rivet nut route. The rivet nut method I can do all by myself without assistance and for a significantly lower cost and much less project time spent. I still haven’t made up my mind because I do appreciate safety. Making decisions like this is never easy.

[Chuck Sea/Tac]

I used them in refrigeration hardware applications, and as mentioned, they don’t always grab well and spin.

[Synchro909]

The floor of a 1930 Model A is wood. You need these T nuts https://www.google.com/search?q=imag...hrome&ie=UTF-8
They are CHEAP and work very well but lubricate the screw/bolt you use.

[Superhart]

To clear up a minor misunderstanding, the floor in my 1930 Model A is not wood. The floor is a modern steel floor. It is for that reason that I could use rivet nuts if desired.

[Harpkatt]

I used rivet nuts to install my handmade metal floor pan beneath my roadster. works perfectly and I've had it in and out multiple times with no issue. I've been dealing with rivnuts for a long time as I was a bicycle tech for a long time, they are used to hold water bottle cages to the frames. The main issues I've had were the fastener seizing into the rivnut . Corrosion from perspiration will lock the two pieces together then when loosening cause them both to spin. Antiseize, grease or wax goes a long way here.

That said I'd say there isn't too much to worry about using rivnuts. if there's an issue file the head down or drill and they pop right out. In a bike frame they are captive so there its a problem there with removing from the tubing. If there's clearance behind it for it to come out it's not an issue and I wouldn't overthink it.

EDIT I guess I missed that you intend to use these to hold the seat to the floor, not the floor to the frame. I would say rivnuts are probably not strong enough for this application.

[Merc Cruzer]

I used them on the frame of the car, how thick is the metal floor?

Mine were hexagon, going into hexagon holes, you will be probably be using round. Could you tack weld them after installation?

[Tom Grz]

I would only use them where there isn’t a better option and only in a spot where you can cut/grind them out if they fail, since drilling them out might not be an option.

[Kurt in NJ]

How often do you remove the seat?
you could braze nuts to a strip of metal and a couple of screws would hold it.

The nutserts installed in a hex shaped hole don’t spin as easy, I have used them for years on Mercedes for license plate mounting

[Tom Grz]

If welding is an option, maybe assemble with a nut and wide fender washer. Tack the washer to the sheet metal in a few spots and tack the nut to the washer.

[bobbader]

While this would be a "cheap" option, how much is your life worth? Or the life of someone riding with you? What happens to those seats in an accident with only these riv-nuts holding them to the floor pan? Those comments about them spinning attest to how little it takes to disrupt their "capture" in the metal they're mounted in. Next question ................. How sturdily would you like seats mounted in your everyday vehicle that would most likely have all kinds of other protection to avoid bodily harm in an accident?

Not trying to pick on you here ............. just thinking of keeping you & yours safe. They call them accidents when you have no idea when they're going to occur.

[Superhart]

I appreciate all your responses. I have read everyone of them and thought carefully about everything you guys have said. I have finally decided how to handle this situation. I will remove the two seats, install two lengths of steel bar, length wise under the floor of the car. The two bars will be 36 x 2 x 3/8. I will attach them to the underside of the cabin floor with steel pop rivets. Then I will locate, Mark, drill and tap these bars for 3/8 inch diameter bolts And tap threads into the bars. Then I will use 3/8 inch bolts to secure the two seats to the floor of the car. I feel as though this type of installation will be quite strong and strengthen the steel floor as well as provide a very secure
Mounting for the seatbelts. How does that sound to all of you? Comments, anyone?

[1oldtimer]

Seat Bolt should be very secure especially in a hot rod. I would go with flat bar stock like you're talking about, attach that to both ends of the body rail frame, drill and tap for truss head machine screws instead of rivets. Drill the holes for your seats (and seat belts) then use cage nuts, you can weld them on or drill and bolt them. All this is a little extra money and work but way better in the long run for ease and safety.