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Underbelly - How to Properly Remove Coroplast

Jim Beletti

Owner Experience Liaison
Staff member
Alliance RV uses 2 fastener types for attaching the underbelly material (Coroplast) to the bottom of the frame. These two fastener types and their removal / reinstallation methods are detailed below. Note that we use fastener type 1 to secure the underbelly in areas that may be more service prone, making entry into this covered area, more service-friendly. Fastener type 2 is more installation friendly, much faster to install and is used in areas that are less service prone.

  • Fastener 1: TEK Screws. These are hex head screws that have a drill point. We use a fender washer with these screws. They are screwed in pneumatically at the plants. In my experience, it’s advisable to only remove these using a small impact driver and a hex head socket. Using a traditional socket and socket wrench or an electric screw driver/gun will typically result in breaking the head off the screw. You really need the action of the impact driver. I use a small battery-powered Dewalt impact driver. Works every time. I typically reuse TEK screws and fender washers and always try to use the same holes in the Coroplast and the frame for reinstallation.

  • Fastener 2: Driven Fastener. These are more nails than they are screws as the shaft is smooth and has a pointed end. Like the TEK screws, we use a fender washer with these fasteners. These fasteners are “driven” through the Coroplast and into the steel frame using a Coil Nailer. While these fasteners have a small observable hex head to them, they are not removable using an impact driver and hex head socket. Rather, in my experience, I’ve found it best to use a chisel and small maul. I insert the chisel between the frame and the Coroplast and I strike the end of the chisel with the maul. I continue striking the chisel until the pin is pulled out of the frame. This takes me about 20 blows of the maul. The nails are bent when removed and are not reusable. I discard the nails and washers and for Coroplast reinstallation, I use TEK screws and fender washers, driven with an electric impact driver.
Below is a link to video example of me removing a driven nail-type fastener.
 
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Famtraveler24

New member
Jim, Now having gotten under my 390, I believe the driven fasteners were used. Take a look at the attached and let me know if you agree. If so, I suspect I'll cut out a section of the Coloplast and not attempt to remove an entire section. Thx again.
 

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Jim Beletti

Owner Experience Liaison
Staff member
Jim, Now having gotten under my 390, I believe the driven fasteners were used. Take a look at the attached and let me know if you agree. If so, I suspect I'll cut out a section of the Coloplast and not attempt to remove an entire section. Thx again.

Yes, that is a driven fastener.
 

MartySchwartz

New member
I had to remove the underbelly for a hydraulic issue and wound up removing all those stupid nails to do so. I found that I could spin the nail using my drill and they came right out. No need to pound the heck out of them with a chisel and hammer. I went to Lowes and picked up a box of the appropriately sized TEK screws to replace them. Getting the correct sized screws allowed me to simply screw them into the holed left by the nails and to reuse the washers from the nails. One issue I ran into was those nails driven in too close to the vertical portion of the beam, the screws jammed and snapped off. The steel of the beam is too hard to drive the TEK screws directly so I had to drill a new hole closer to the edge and then install the new screws.
 

Jim Beletti

Owner Experience Liaison
Staff member
@MartySchwartz - great to hear you got those nails out and replaced them with TEK screws when you buttoned the underbelly back up.

I was able to spin those driven nails with a small impact socket but they would not spin out for me. So I gave them the beating they deserved :)

Glad you had an easier time removing yours :)
 

MartySchwartz

New member
@MartySchwartz - great to hear you got those nails out and replaced them with TEK screws when you buttoned the underbelly back up.

I was able to spin those driven nails with a small impact socket but they would not spin out for me. So I gave them the beating they deserved :)

Glad you had an easier time removing yours :)
Well, they did not spin out like a screw but they did loosen up enough to pull out with a little down pressure on the washer while turning. A few required a hard pull with vice-grips but they all came out with out too much trouble.
 
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