Attaching DIY camper direct to Tacoma frame.

[otis24]

Tacoma boxes are fiber-reinforced resin, so they are probably fairly stiff. The bolts are sleeved that go through the bed floor to the frame, so there's accommodation for movement. In fact there's enough movement that the bed will squeak when the material under the bolt heads wears down. This allows the box to burnish the tops of the supporting towers and it's annoying. I made UHMW pads to fit between the box and frame to get rid of it. The beds themselves are completely different in construction. The inner bed is a single molded cavity and the fenders are essentially just cosmetic skins. So the real strength is the composite inner bed, not the bed rails.

https://www.tacomaworld.com/threads...-flaw-explanation.388873/page-3#post-12873622

When I mounted my WilderNest on my Tacoma I anticipated the additional flex, at least compared to the truck I had it mounted on before, a 1991 Hilux/Pickup. Those had relatively rigid frames, fully boxed, and the beds themselves were double wall construction with welded seams. So they were also relatively rigid.

On the '91 the 'Nest was bolted directly through the bed frame rails with six 5/16" bolts and a layer of closed cell foam to seal against water and dust. That stuff squished flat instantly, its pretty cheap hardware store junk. But none-the-less it lived like that for at least 12 years only getting removed to replace the foam once in a while and clean the camper. The fiberglass developed a few stress cracks in the gel coat from the knocking around off road but it was manageable.

Fast forward to the Tacoma. I removed the top plastic plate to give a flat surface all around, then put a 1/4" layer of solid rubber on the bed rail and closed cell foam on top. Used four 10mm clamps to the cargo rail instead of through bolting. The camper is held fast but I am trying to let it have some give and isolate the vibration and movement. I've had the 'Nest on my Taco now for about 6 months and haven't done a tremendous amount of off road. White Rim, knocking around San Rafael.

View attachment 496580View attachment 496581View attachment 496582

I heard and subsequently noticed a sizable crack in the structural fiberglass around one of the ribs last week with the truck crossed up. So there's more flex in the Taco frame than I assumed. I'm rethinking how I mounted my 'Nest, not sure if I'm going to try isolating the camper more or reinforce the bed rail.

I don't want to build a subframe that ends up actually stiffening the frame but I think letting the camper float relative the bed rails is important. I'm trying to find a suitable rubber substitute for the 3 stacked washers in the mounting bolts (these were necessary to prevent pulling the mounting rail down). I think that ended up being too rigid and is still twisting the camper. It's not clamping down on the bed rails all that hard it's still focusing a lot of force on four stand-offs.

What year is your Tacoma? I know the 2nd gens and the 3rd gens have kinda flexable bed sides. If you have any weight on them like a roof top tent it's a good idea to get some bed stiffeners like these -
https://www.chaosfab.com/accessorie...PKxyBMjOjIhdDcgJL4TrWCiQnf9Hnz5QaAssAEALw_wcB

 

[DaveInDenver]

What year is your Tacoma? I know the 2nd gens and the 3rd gens have kinda flexable bed sides. If you have any weight on them like a roof top tent it's a good idea to get some bed stiffeners like these -
https://www.chaosfab.com/accessorie...PKxyBMjOjIhdDcgJL4TrWCiQnf9Hnz5QaAssAEALw_wcB

Mine's a 2nd gen, 2008.

And you mean a lil' something like these? Way ahead of ya.

Mine are from Morgan at ATH Fab over in Nevada. They pulled the sides in, even before I ever put on the 'Nest they were starting to splay.

 

[otis24]

Mine's a 2nd gen, 2008.

And you mean a lil' something like these? Way ahead of ya.

Mine are from Morgan at ATH Fab over in Nevada. They pulled the sides in, even before I ever put on the 'Nest they were starting to splay.

View attachment 496704

Lol...yup those are the ones.

I have a 1st gen with just a camper shell on the bed and I suspect my bed sides are spreading a little. My camper shell hatch doesn't quite line up anymore. Although, it could be that it's been like that all along and I'm just noticing. It could also be the bed is fine and the shell is wonky.

My solution is to get rid of the bed and the shell and build a light weight minimalist flat bed pop up wedge style camper. I could probably just leave it alone but there's not a lot of fun in that.

 

[DaveInDenver]

Since I dropped down awkwardly on my bumper and right rear fender skirt a couple of weeks ago my tolerance for the bed has also further waned. I wanted to avoid a high clearance bumper and cutting sheet metal but now it's not a concern. Knew I was tempting fate.



I always wanted to build a flat bed for my '91, wwhich also eventually suffered failing bed sides. On that bed it took 20 years to happen though.



Never did get around to it but I will on my Taco. When I do I'll also reinforce the frame somewhat. Not fully boxing it since the other major issue with them being that pesky frame rot and being open lets me keep after that better..

 

[TernOverland]

Tern -

Did you also do the test before the bed was removed? I wonder how the seemingly stiff composite bed accommodates the frame flex you observed.

I have looked at the flex in the past, but I did not do a measured comparison this time because it didn't matter to me. The bed has very little effect on the flexing of the frame. As others have noted, Tacomas are LIGHT trucks. They can carry substantial loads for short distances, but any attempt to heavily load these trucks permanently needs be seriously considered.

 

[rruff]

The bed has very little effect on the flexing of the frame.

This is true. Beds are not stiff in torsion at all. None of them that are open at the top.

 

[DaveInDenver]

The bed must have some effect on the flex of the frame. There's no obvious accommodation for them to move, e.g. joints or isolating mounts. And the floor of the composite bed is webbed for some reason.

 

[rruff]

None of the individual panels of the bed are stiff in torsion, and they are allowed to freely flex relative to each other.

If you take the bed off the truck this would be easier to see. If you rigidly support the front, the rear can tilt relative to it quite easily. If it was a fully enclosed box, it would be much stiffer. Which is why we need to consider this when we mount campers.

 

[TernOverland]

The floor of the bed is very flexible, even though it is webbed. As stated, the top is open, and so is the back. The front bulkhead is all that stiffens the bed, and it is against the cab. It is similar to a 3 point mounting system. The front double mount can be fairly rigid, but the frame twists around it. The mounting holes in the bed are much larger than the bolts, so there is a lot of room for the bed to move as it twists.

The Tacoma long bed, by the way is pretty darn light. The bed alone weighs 205 pounds, and the tailgate weighs 38, for a total of only 243 pounds. By comparison, my Leer 180CC canopy weighed 220 pounds. We are not talking heavy weight components here.

 

[DaveInDenver]

None of the individual panels of the bed are stiff in torsion, and they are allowed to freely flex relative to each other.

The 05+ Tacoma box isn't individual panels, it's a molded tub with cosmetic fender skins bolted to the sides. I agreed with you on older trucks, double wall steel with seams and the front panel being bolted to the front on 79-95 trucks. On the Taco there's that one steel rib at the back, which of course is where we bolt the reinforcements in, so there's definitely something left to be desired with box rigidity there. I know that.



I'm not making the argument that a pickup box is particularly rigid, certainly not so at the tailgate end. There's additionally a number of issues Toyota has with the composite bed, not just frame flex. The differing rates of expansion require tolerance in the mounts otherwise the bed floor might buckle or crack in exceptionally cold or warm temperatures, so there obviously has to be accommodation and the webbing is probably there to minimize that as much as anything else.

If you take the bed off the truck this would be easier to see. If you rigidly support the front, the rear can tilt relative to it quite easily. If it was a fully enclosed box, it would be much stiffer. Which is why we need to consider this when we mount campers.

I have not yet removed my 2008 bed but did on my 1991 (this to replace the front panel) and 2001 (when I welded on frame plates). I know they aren't rigid alone. But you can't analyze the frame and box independently and draw to a conclusion. It's a truss when you fasten them together, the two together are more rigid than each individually. It's my $0.02 that the Tacoma box is intended to do more structurally than we think. But the whole rear end is flexible, no doubt about it.

If there was a lot of flex then the tailgate would bind when the truck is twisted. The gaps do change a little but I'm not aware of people getting buckled tailgate skins or anything. So I guess the bed is twisting uniformly with the frame, but then what is the happening when you bolt on a topper? I can tell you a WilderNest is not going to flex willingly (they do develop stress cracking over years of 'wheeling, that is definitely true).

If there's movement in all of this it's got to be small. We're not talking about a Unimog frame type of twist necessitating true pivoting mounts.

Anyway, I have unlatched the rear window of my camper and hold it closed with a bungie on harder trails for years. I worry that holding it fast will shatter the glass, although that's never actually happened to me. Old wives' tale, I dunno. I think it helps with the jarring, too, though.

 

[TernOverland]

The issue, going back to the initial post, was whether it is a good idea to bolt a chassis mount body directly to a Tacoma frame. The frame alone is very happy to twist, so whatever body is mounted must move with it, or be strong enough to resist the movement. The bed moves with it, but the body will be a full box. Boxes generally don't like to be twisted. To me it's a pretty clear application for an isolation subframe.

 

[Deleted member 144299]

I am so happy this thread exists! I've been mulling over a DIY camper for awhile now and I am finally starting to rough up the build. One of the biggest questions I have had has been about frame flex, having read up on 3 point mounting systems for larger expo rigs I am not sure if it applies to my short bed taco. My plan has been to just use rubber bushings and forgo a pivoting subframe. Maybe you guys can shine some light on this for me, everyone has great input! I am planing on a Maltec style design but keeping the camper separate from the cab, all aluminum frame and skin style build. Inside will be really simple with just a table, small cabinet, 15 gallon water tank and 1 house battery. Trying to keep it as light as possible!

So my question is do I need a pivoting frame with this? Again this super rough and early on but see the attached images, one is a Photoshop mock up of what I am looking to build the CAD is a quick mock up of the frame (in-prog).

Thanks for any help you guys can offer!

 

[TernOverland]

I assume the frame will be welded? Welded aluminum frames can develop stress cracks from twisting. You do have a short bed, so that helps. After you get the bed off, lay a length of steel or aluminum across the front and rear mounts. Lift one wheel till you get maximum twist and see how the two pieces are twisted relative to each other. That will inform your decision. Rubber bushings may be soft enough to allow the movement, but then again, a simple 3 point is not hard to build on these trucks. If you can build that whole shell, the 3 point should be a snap. This company has components that make the fabrication simple: https://www.ruffstuffspecialties.com/catalog/FABPARTS.html

 

[Deleted member 144299]

Yes I am planning on welding the aluminum frame but also looking into alternatives including maybe using steel instead if the weight isn't a issue. I guess in the grand scheme of this project a 3 point wouldn't be much more work I am just trying to avoid unnecessary steps. Thanks for the advice @TernOverland I bookmarked your website awhile back and will certainly be ordering from you in the future!

 

[rruff]

Yes I am planning on welding the aluminum frame but also looking into alternatives including maybe using steel instead if the weight isn't a issue. I guess in the grand scheme of this project a 3 point wouldn't be much more work I am just trying to avoid unnecessary steps.

I nixed the 3-point on my build because I didn't want the extra height and complexity and subframe that a pivoting mount would have. And I don't think I really need it. Going with poly cab mounts.

Steel will be heavy. I'm guessing you have metal working experience, but IMO fiberglass, foam, and wood are the best camper materials. Wood of course needs to be fully protected from water, and joints screwed and glued. I had no experience, and it wasn't hard to learn fiberglass. Wet layup. I'm doing mostly flat panels with contoured cab-over and radiused edges, but you can make all sorts of interesting shapes if you want. I considered building it like an upside-down boat, with curved sheets. Make the shell out of foam, FG the outside, then just glue thin ply to the interior surface. Very aero but not very space efficient. Mine is nearly all FG and foam with some wood for mounting. The materials aren't expensive either if you know where to look.