Discussion: Alternate methods for re-securing underbelly material

[Jim Beletti]

I've had a number of RVs over the last 20 years and with all of them, I do a number of modifications. These always include running wires and often plumbing below the floor within the frame. This means I am always removing my underbelly material.

Historically, the industry typically uses hex-head, coarse thread screws with drill point heads. Tek is a brand but we commonly refer to these screws as Tek screws. In more recent years, some manufacturers have begun to use a combination of Tek screws and Coil Nailer nails.

I'm not much of a fan of the nails and they are not reusable. As such, when I remove nails during my projects, I replace them with Tek screws.

At the moment, with my Alliance Delta 262RB, I have pulled most of the underbelly down. I had to cut it into a couple of sections to pull it down. As I am nearly completed with projects within the frame, I am contemplating an alternate method of resecuring the underbelly material. Rather than use all Tek screws with fender washers, I'm considering using stainless steel PlusNuts or RivNuts with bolts and fender washers. I haven't decided which - or if at all.

I don't have access to my RV at the moment to know the I-beam flange thickness or flange width from edge to web. Having the flange thickness will determine the grip-range I need in a fastener and having the flange width will determine whether I use a PlusNut or a RivNut. The PlusNuts need some space to span out on the flange whereas the RivNut requires little space to mushroom out. I'm favoring RivNuts but have little experience using either.

I am certain that I will reenter my underbelly at some point down the road, so I want to choose the fastener that will stand up to a bolt being removed from it and reinstalled without allowing the fastener (PlusNut or RivNut) to spin. By the way, I'm thinking 1/4-20 on the fasteners as it seems like the right size for my application and threaded bolts in that size are plentiful.

This all said, does anyone care to comment or weigh in with their experience with the use of PlusNuts and RivNuts? Especially in thicker gauge steel substrates and especially with removing and reinstalling bolts into the fasteners over time.

 

[Shoaf]

That sounds great to use rivnuts.
I work with this type of fasteners every day in building Western Star trucks.
You will need to know the thickness of material they are going through. To get correct grip range. I would use metric size 6mm. The screws will stay tight better than standard screws.


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[Jim Beletti]

That sounds great to use rivnuts.
I work with this type of fasteners every day in building Western Star trucks.
You will need to know the thickness of material they are going through. To get correct grip range. I would use metric size 6mm. The screws will stay tight better than standard screws.


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Thanks for the feedback on using a RivNut and on the fastener size. I’ll consider both.

When I get home from this trip overseas, I’ll mic the flange.

 

[RockDr896]

Great topic! I just replaced my nails with screws and larger washers, in anticipation that I will some day need to access the underbelly. I was thinking of making the removal easier, by making smaller sections removable. My 370FB has a few items, like a gas line and the axles, that is going to force me to cut the "Installed in 1 piece" under belly on my RV or go through the hassle of removing it all. Any ideas on how to best handle doing this? Is the only solution tape? Has anyone tried this approach? I like to make future jobs easier, by fixing things like this on my time and not in the heat of the battle. I would love to hear others ideas.

 

[Shoaf]

You could use thin strips of aluminum to go length of cut and use screw on each side hold pieces together.


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[Jim Beletti]

You could use thin strips of aluminum to go length of cut and use screw on each side hold pieces together.


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@Shoaf - for piecing underbelly sections back together that I have slit from frame rail to frame rail, I have use 1x2 or 1x3 lumber to do as you suggest with metal strips.

That said, I'm considering adding a piece of 1" steel angle stock to go across the coach from on top of the bottom frame flange to the other side. In this manner, I could add RivNuts to it and do my thing - if I go that route.
Lots of great ideas here. Let's keep this conversation going

 

[RockDr896]

This is what I have been thinking, since I tend to do any project solo. Rarely scream for help. So call this my 1st pass of preventing me screaming "HELP"!!. The idea of this drawing is for it to perform like a curtain. Once I unbolt the 2 angle pieces, it would slide along the frame and how much drops will depend on how many side screws I remove. Any improvements or thoughts of why this might be a bad idea?

 

[Jim Beletti]

This is what I have been thinking, since I tend to do any project solo. Rarely scream for help. So call this my 1st pass of preventing me screaming "HELP"!!. The idea of this drawing is for it to perform like a curtain. Once I unbolt the 2 angle pieces, it would slide along the frame and how much drops will depend on how many side screws I remove. Any improvements or thoughts of why this might be a bad idea?

I like your idea of back-to-back angle stock. I think I’d prefer to invert them and have them set flat onto the I-beam flange.

Let’s keep the ideas coming

 

[Jim Beletti]

@RockDr896 - maybe use t-bar channel.
Example

 

[RockDr896]

@RockDr896 - maybe use t-bar channel.
Example

I thought that, but I settled on the idea of angle. It would make putting it back up easier for one person, by using the screws which hold them together as a sort of puller to recreate the exact placement every time. So I would set the center screw and then the outside ends. Might even make it a bolt. I will take pictures when I am done and let you know what changes I made, due to over thinking this job.

 

[Jim Beletti]

I thought that, but I settled on the idea of angle. It would make putting it back up easier for one person, by using the screws which hold them together as a sort of puller to recreate the exact placement every time. So I would set the center screw and then the outside ends. Might even make it a bolt. I will take pictures when I am done and let you know what changes I made, due to over thinking this job.

I hear ya on over-thinking projects
Love to see what it looks like wen done. Angle stock is easier to find, so putting them back to back is understandable. If I do something like this, I really want to try to use RivNuts as I remove my underbelly a nit more often than most people do. Except maybe you