Attaching the cabin to the chassis

[James9324]

I’m sure there is a post on this somewhere. I have read a few posts on building the cabin separate from the chassis and then connect it after it’s built. So my question is how do you connect it? What is the best way? Lag bolts? I thought about U clamps too.
Do I screw through the frame of the chassis? Any info would be appreciated. Photos even better, I’m a visual person lol.

Thanks everyone!
James

[drhill]

I actually built mine so it is removable. Not something you want to do all the time, but I take the camper off in the fall and put it back on once all the spring chores are done with the trailer (hauling shingles this week, then firewood) For the hold down, I have it bolted at/near all 4 corners. I took a few inches of steel strap (about 1/8 x 3/4") and drilled a couple holes in it. I then inserted 1/4" bolts and tack welded those in place. So it resembles a U bolt but is pretty much flat on top. I put the 4 of those in place and then crawl under the trailer and do up the nylock nuts. There is no need to have the wife hold a wrench on the top of the bolts as they are welded to the steel strap.

You can see some pictures here: http://tnttt.com/viewtopic.php?t=61318

[Juneaudave]

Not sure how your trailer is built, but one common method is to use trailer deck screws. With these, you drill a pilot right through the cabin floor into the trailer frame and secure....https://www.trailerdecking.com/trailer-deck-screws.aspx

[Sparksalot]

I ended up using carriage bolts. I also bolted the floor to the frame before the walls went up, so many of those bolts aren't exactly accessible. I ended up with 13 bolts, for what reason I don't even remember. There was a lot less information around at that time.

[James9324]

I haven't built it yet but it will be made out of 2x3 tube. I'm thinking then just to have some attachments welded on for screwing the floor to the chassis.

Not sure how your trailer is built, but one common method is to use trailer deck screws. With these, you drill a pilot right through the cabin floor into the trailer frame and secure....https://www.trailerdecking.com/trailer-deck-screws.aspx

[halfdome, Danny]

The best way is to use elevator bolts.
Just drill a shallow hole with a spade bit and the bolts will be flush to the floor.
I use 3/8" and I have mounting tabs welded to my chassis, using lock tight nuts.
I build on the chassis it's a lot easier than lifting it on after construction, less chance of mistakes.
Danny

[Tom&Shelly]

I ended up using carriage bolts. I also bolted the floor to the frame before the walls went up, so many of those bolts aren't exactly accessible. I ended up with 13 bolts, for what reason I don't even remember. There was a lot less information around at that time.

Ah yes! My first mistake with our teardrop: I located two of the 8 bolts right where the galley bulkhead went. Solved it with two "mouse holes" in the bulkhead. If absolutely necessary, I could get those bolts out.

The trailer frame has triangles welded in to strengthen the cross-members, and each has a 3/8 inch hole drilled that the bolts go through.

Tom

[working on it]

* I used eight 3/8" carriage bolts thru 1/2" birch plywood, thru two angle steel crossmembers, as the base for the floor. I semi-countersunk them (crushing the heads into the plywood) so they wouldn't make visible bumps when I overlaid the birch ply with 1/4" luan-faced ply (using TB2 to glue the plys together).

* After the glue dried a week (compressed with a hand-roller, then with weight applied on top), I used thirty-eight TEK screws thru both sheets of ply, into the perimeter frame of 11 gauge rectangular steel tube.

*

bolted & screwed to frame, in two stages.jpg (78.72 KiB) Viewed 1196 times

[aggie79]

Keep in mind that your hitch pin, depending on receiver class, is either 1/2" or 5/8". That is all that will be holding your teardrop trailer to your vehicle. So...no need to use too many bolts to tie your cabin to your frame/chassis. Four (4) bolts would be convenient to tie all corners. Personally, I used trailer deck screws and fastened through the floor into the square tube frame rail.

[working on it]

* This subject has come up repeatedly over the years, including one thread four years ago attaching deck to trailer, bolts or screw? http://tnttt.com/viewtopic.php?f=35&t=68349, where aggie79, and I both stated the same things in almost the same manner. However, KCStudly made a good point about the benefits of over-engineering, to be on the safe side: http://tnttt.com/viewtopic.php?f=35&t=68349#p1206454

Just a little engineering spitball here, comparing the cross sectional areas is okay for a back of the napkin kind of approach, but another way to look at it is friction in the "bearing face" of the joint. It isn't always the shear strength of the fastener that makes a joint; sometimes it is the tensile strength. If the clamping force is great enough, then the friction between the two surfaces insures that there will not be relative motion; w/o relative motion the fastener will never see shearing forces. So with more smaller fasteners you get a more uniform clamp, and therefore more uniform friction. (TLAR analysis in effect.)

Another argument in favor of several smaller fasteners is that we are dealing with wood. Wood can move around and change with humidity and temperature (hopefully less so when we do a good job of waterproofing!), so by my way of thinking a few extra small fasteners hedges the bet if one or two should happen to become compromised.

Now this has come up many times before, some may argue that you could get away with no fasteners and your cabin might never slide or fall off of your trailer, that since your trailer hitch pin is just 5/8 diameter that you might get away with just a couple of healthy bolts. I say nerts to that. I believe that the cabin should stiffen the trailer frame to prevent relative motion when the chassis would otherwise flex. By eliminating relative motion you eliminate the potential for chaffing between the surfaces and the wear that might otherwise occur to damage that precious waterproofing. So it makes sense to me to spread more smaller fasteners over the length of your trailer, than to just use a few in, say, just the corners. This is also another good argument for using some sort of caulk or bedding compound when mating the cabin floor to the trailer.

Over engineered? Maybe. That's right, I'm still not camping yet , but I always say if it doesn't take anymore effort to do something with a little logical thinking behind it than it does to toss a dart and see what you get, then why not put a little thought into the process.

Truth is that however you get there, most methods will work one way or the other. There are no rules, except to have fun doing it!