How many bolts to attach a floor on 4x8 trailer?

[Franco Novo]

I'm sure I am beating a dead horse here. :roll

Not really, I like a reasonable amount of bolts...in case I want to slide the box off....and replace it with a new model...or , to use the trailer as a flatbed for hauling stuff. makes it more versatile....

[rowerwet]

Being a foamie, rigidity in the body is much less than a wood tear.
Like was said, the pop up I tore down for the frame had six self tapping screws to hold the much heavier camper onto the frame.
The only trailer failure I ever witnessed was a tounge ripped right off a tilting open sled trailer when the corner caught a snow bank at speed.
Most builder's go to overkill.

[Franco Novo]

Most builder's go to overkill.

absolutely....as I mentioned, 39 years in the building trades , countless remodels...attest to that
it's mostly amateurs....where 2 screws would do....they will use 20.

Having said that, I think the biggest kick out of the Teardrop or Tiny Trailer...is building it.
I'm just waiting for another sale on trailers at Harbor freight so I can get the next one going........

I see you made that massive looking foamie....you mentioned putting an extra story on top that ever happen?
also, what is the tow vehicle ??? .looks fairly modest....
I like pulling with a small car, just to show the guys getting 5 mph with their massive trucks that it could be done. ( I see the shaking their heads when I pull off ha.)
Of course, I think the ford Focus Wagon is pushing it a little bit.....but I just might try a foamie next time....just 1 inch foam and some thin veneer skin

best'
Franco ............................

[Poorlytiedfly]

On my 5'6"x10'6" build I am attaching the floor with 12 1/2" grade 8 bolts... overkill?

[KCStudly]

Yes, very much so.

I have also been told that my sixteen (16) 3/8 inch SS bolts on a 64 x 9'-8" are also overkill.

[noseoil]

Nomad, good lard Jasus bye, that's 211,000# of shear value! Met'inks it's a bit of overkill. With a 1/2" grade 8 bolt, one would be enough for your build.

While I'm a charter member of the OCD club, this is too much even for me to ponder. 6 - 5/15" grade 2 bolts would give you 20,400# of shear value and be more than enough to hold things in place. Save that money & spend it on something else for your build!

[rowerwet]

You only need one, however to keep the tear from turning on the frame you want a second bolt. I have one at each corner to keep the loads even and the rather flexible frame square. Any more than that is wasted weight and a potential leak/rot point.

[KCStudly]

I think you want at least six (6). Two at each end and two near the suspension. The cabin is the rigid strength and the trailer chassis is somewhat flexible. I could picture a scenario where if you just fastened at the front and rear the weight of the suspension oscillating down the road could have the chassis flexing under the cabin, and that might set up a chaffing situation that could deteriorate your hard earned waterproofing (unless you glue the cabin down with sealant or adhesive). $0.02

[rowerwet]

But unless you are on serious washboard roads, the weight of the tear will always be pushing down in the middle, anchor the corners and you won't have any lifting in the middle. Based on my observations

[KCStudly]

Probably true, but I am planning on long miles of forest service road, so I guess that is part of my plan.

Also, just because you can get away with something doesn't make it the best plan. Just saying, I don't think six (6) 3/8 bolts should be considered over building.

[rowerwet]

It's all opinion as the post pointing out the shear force proved

[azgreg]

I figure one should do it.

[angib]

Men do like to buy grade 8 bolts, like it is the entry permit to a secret society of knowledgeable men.

The problem is that no-one has yet invented grade 8 plywood, so the super-strong bolt will just pull out of the plywood if put under the sort of stress that needs grade 8.

Really, it is the size and thickness of the washers used over the plywood that splits the men from the boys......

[yrock87]

Men do like to buy grade 8 bolts, like it is the entry permit to a secret society of knowledgeable men.

The problem is that no-one has yet invented grade 8 plywood, so the super-strong bolt will just pull out of the plywood if put under the sort of stress that needs grade 8.

Really, it is the size and thickness of the washers used over the plywood that splits the men from the boys......

you beat me too it!

16 bolts seems overkill, but 1 will not provide necessary attachment force because the wood will fail well before the bolt. that is unless you use some serious washers.

for what its worth, I will be using 3x 3/8s bolts down each side with the largest washers I can manage and some rot resistant hardwood (recommendations?) at the attachment points.

as another point of reference in addition to the example of the pop up using 6x self taping screws, the average pickup trucks only use 4 bolts (6 for a longbed) to secure the bed (and by extension the load) to the body of the truck. once again that is metal to metal so it is an apples to oranges comparison to a wood(or foam (or wood and foam)) teardrop, but more does not necessarily mean better.

[noseoil]

I used 5/16" elevator bolts for my build, plus a couple of carriage bolts when I couldn't find long enough elevator bolts. It's way-overkill, but 3 per side on the frame & 3 more in the middle at different points. Elevator bolts have larger heads & a square shank, so it's like a washer counter-bored into the wood surface.

Grade 8 bolts are overkill, they're used where excessive forces are concentrated in the loads being carried. They are a much stronger alloy than common hardware store bolts, which are plenty strong enough anyway. The grade 8 alloy is rated at 150,00 psi!

I would use white oak if you're concerned about a good rot-resistant hardwood. Strong, tough & heavy, use it sparingly. I used red oak for my hatch spars, as I wanted the higher fiber strength of oak to hold fasteners for the hinges. Poplar is too soft. The lower deck framing is just poplar at the frame. Not too worried about the bolts pulling through. If that happens, we have other problems to deal with.