My Airstream came from the factory with a sewer carrier fastened to the underbelly which I am removing and replacing with 2 new carriers I am building out of PVC.
My question is, has anyone ever fasteneted to the underbelly with self taping screws? The existing sewer carrier is fastened that way, I am just concerned I will hit something up in there...like the frame?
Self tapping screws are the way to go. Use short screws that don't penetrate the belly pan by more than 3/8 inch or so, since all you will be attaching to is a thin piece of aluminum.
I would recommend using Olympic rivets, you don't have to shave them since they won't be visible, save money on the rivet shave. The belly pan gets a lot of vibration from not only the trailer but the airflow inder the trailer. The Olympic rivets will give you a much better bite than screws. Screws can very easily vibrate loose in the belly pan. Additionally, the belly pan is relatively thin metal so the screw doesn't have a lot of metal to bite onto. Holding the tubes up puts a lot of pull along the screw's axis with maybe one full thread engaged with the belly pan. The Olympic rivets have wings that spread out to give better distribution of the force.
You don't want to attach to the belly pan, unless you want to pick up your tube somewhere down the road. I think the bouncing will pull rivets right out .
Locate a frame cross member - drill and tap for a small bolt, and attach the hanger with the bolt and washer. I initially used two of the hangers shown, but went back and added a third. I didn't want one to pull out and then an end would drop - with three it's secure. If you haven't drilled and tapped before, and screw it up somehow, you can move the hangar an inch over and do it again.
One side of the tube feet should be screwed into the cross member(s). That is the way mine came from the factory. I added two additional ones. On the other side of the feet I made a plate of thicker aluminum, about 4" X 4" and riveted in each corner of the plate with Olympics. I then drilled a hole in the plate, through the belly skin, and used stainless screws to attach to the plate and skin. This method displaces the weight over 5 fasteners and a broader area.
One of my tubes carries 22 pounds of water softener and stand. I additionally strengthened that one with two modified PVC pipe hanger for residential plumbing and attached them to a cross member as well.
I'll see if I can find pics.
__________________
-Rich-
"If the women don't find you handsome, they should at least find you handy." - Red Green
Thanks for all the help. I am leaning towards leaving the factory sewer carrier in place and adding the second that is capable of holding the fittings. The factory unit is 4-3/8" ID.
I priced 5" PVC (yes, it actually exists) but in the end with some sacrifice I found a sewer carrier with a full 4-5/8" ID that will work.
I would not know how to locate cross members and since I will be fastening this one next to the existing one, I will probably miss a cross member. So now I think I will go with the suggestion of adding a small section of aluminum riveted to the underside, then screw to that.
I found a link to the Olympic rivets online, now I need to find a section of aluminum. Any suggestions? Thanks
Please don't misunderstand me. One side of the tube must fasten to a crossmember. Only the other side can go into reinforced belly skin. There's a cross member wherever you see a line of rivets in the belly skin going from side to side.
Your tubes will have to be not right next to each other. You also have to work around gas lines, etc.
You can get small sheets of aluminum at your favorite big box. HD has it.
__________________
-Rich-
"If the women don't find you handsome, they should at least find you handy." - Red Green
I left behind one such undebelly sewer hose holding PVC tube many years ago. It was screwed into the frame on both sides. Ever since, I cringe at what may/could-have-easily have happened to all the other drivers encountering that debris and I promised to never install such a system again because it resists being inspected for security and safety. So, instead, I've since used a 5" square (not 4" because 4" is too small for the hose ends/fittings) white vinyl fence post, with matching vinyl caps and SS linch-pins to fasten caps. The fence post was already a corner post so already had 3 holes on two adjacent sides; I mounted one side of holes downward for drainage, and the adjacent side aft for air flow through, but not rain into. The entire post is cut to just over 5' and sits on my front A-frame between the aluminum front skin and just aft of the equalizer brackets, fastened to the A-Frame with 3 per frame-side heavy duty 36" UV resistant Zips-Ties and backed up by two lag screws side in each frame rail. All easily accessed and all clean, neat, tidy-looking and most all, easily inspected for safety and security.
The Pipe Schedule is Schedule 5 for septic/farm drain piping; 4" diameter. Very thin wall and if you cut it (10 ft length) to use the bell end, your hose fitting will slide in and out easily. You will need to jury-rig a closure for the removable cover since the bell end is oversize
I attached my carrier to the frame using copper plumbing strapping. Had to drill first and then use self tapping sheet metal screws
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