Mounting box on back of Fleet: Advice appreciated

[Redfish]

I’m about to drill some holes in my camper floor, but before I do something unwise, I thought I’d check in here first.

I’m attaching an aluminum dry box to the back of my 2016 Fleet. The long skinny box (35” long x12” wide x10.5” tall) mounted next to the door will weigh approximately 32 pounds fully loaded. The box will be supported by two aluminum brackets, an upper one bolted vertically and spanning from a jack bracket across to the grab handle area, and a lower one bolted horizontally up through the floor and inside a cabinet (see photo with crappy rendering of lower bracket).

My questions have to do with the bottom bracket, which will be 10” wide x 14” long x 0.25 thick and will be anchored by 2 sets of 2 side-by-side bolts. Each set of bolts will pass through a bottom cleat and the floor pack and will be backed by interior 3/16” plates. The most rearward set of bolts will also pass through the dark brown, plastic covered “threshold” piece (indicated by the arrow in the photo). I could use lag screws instead of through bolts, but want to avoid tear out.

Here’s my questions:
1. Exactly how is the floor pack constructed? I can see that it’s sandwich of some kind but I’m unclear about how it’s made and what it consists of.
2. Do the wooden wear cleats on the bottom of the camper line up with a wooden frame member in the floor pack or some other structure that I won’t crush when I tighten down on the nuts?
3. What is the “threshold” made of and can I drill through it with impunity (e.g., no wiring or other regrets)?
4. Lastly, how would you recommend I seal or otherwise handle the external contact between the aluminum bracket and wooden cleat to prevent rot?

Many thanks in advance for your advice and experience.

Jeff

 

[CougarCouple]

Hello redfish
Is there a way to mount to the truck bed instead of the camper. Thread serts like Hodakaguy was using would be useful for that.
Just asking as looks like the box slides on the side of the camper into the truck bed.

Russ

 

[Redfish]

Hi Russ,

Thanks for taking a look at my problem. I'm afraid my description or photo/drawing may not have been clear. The drawing imposed on the photo is of just the bottom bracket that the box will sit on, not the box itself. I've attached a different photo/drawing showing the whole set up, plus a rendering of the bracket itself. Hope this is clearer.

However, I'm intrigued by the idea of threaded inserts, but wonder about their holding power in this application where the downward force would be in line with the inserts.

Jeff

 

[PackRat]

Jeff....

I think Russ may be onto a different approach, but I can't see enough of your camper-to-truck bed to tell if this would work:
With even 32 lbs on it, you run the risk of cracks from the constant vibrations going down many roads and off-roading. I see your camper extends past the truck bed so I would first ask if you couldn't just rig up a bracket on the tailgate for the cargo you intend on carrying?

If that is not feasible, then I wonder if you could fabricate a bracket that is bolted to the rear bumper once the camper is put into the bed of the truck? It would be a platform supported not by the camper but by the truck. In addition a gusset plate or at least a bracket that is bolted to the end of this platform and to the inside of the truck bed where the stake pocket is located to keep it from vibrating and breaking the aluminum would work.

I get that you have some reservations about drilling holes in the camper and possibly not only hitting wiring or something, but weakening the floor panel at the rear. I think trying to engineer that platform by mounting it on the truck instead of the camper might solve those issues. Having said that, I see guys have mounted brackets on the rear panels of all kinds of campers but that is just one way to carry things from gas/water cans to propane tanks to other kinda heavy objects....

How you choose to do that is up to you though....

 

[Redfish]

Packrat,

Thanks very much for your comment. Take a look at the additional photo and drawing I just posted to see if it changes your mind or gives you a different idea. I am worried about the stress to the camper. Since the camper and truck move somewhat independently, I can't see a way to attach the box to the truck and camper at the same time. I considered various bumper with swing out combinations and they all add more than 150 lbs to the back of the truck--without any cargo.

Jeff

 

[ntsqd]

Keep in mind that any sudden dynamic events, the speed bump that you didn't see, the pothole, etc. will cause that box and it's contents to "weigh" at least 3 times what it does sitting still. Then factor in what that "weight"'s leverage will have on the supporting structure and the forces can get quite large without it seeming like it would..

 

[DavidGraves]

Howdy


We carry our box on a 1/4 Alum plate that is bolted to the bumper.....mount box on plate after camper is loaded.

Try to keep it light, hatchet, tow strap, PFDs ....sometimes trash from the road or trail.

No stress to camper.

David Graves

 

[longhorn1]

Either gas line or wiring or both run under the door jam.

 

[CougarCouple]

Ok redfish I see more clearly now, the rain has gone! ( sorry can't resist)

Personally I think that's a lot of weight to hang on the back maybe a metal plate secured to the truck bed bent in a Z to support to weight and a plate up higher to secure the top end, from tipping. All weight on bottom. I understand the need to have xtra cargo space, just finding a way that will work but not tear apart your camper.
Russ

 

[Redfish]

Packrat, David and Russ,
I think you are right that transferring the weight of the box onto the truck bed and/or bumper is the way to go. Per your suggestions, fabricating something like what is in the photo below (from the Tardis build, I believe), which could either be fixed or designed to pivot, would be a better solution. I did a bunch of research on WTW, Expedition Portal and Tacomaworld and talked to a lot of bumper fabricators and couldn't really find a good solution that fit my needs.



Any kind of bumper-based solution means I'd probably have to invest in an aftermarket bumper, since my stock 2016 Tacoma doesn't really have one, which would also require new springs and possibly other suspension fixes beyond my current airbags, adjustable shocks/struts and e-tires. My camper is on my truck 5 months out of the year, not full-time.

ntsqd,
Dynamic loading is definitely a concern. But, the loaded 32 lb. box is less than the full 40 lb. 5-gallon gas cans that folks are mounting, apparently with no harm to their campers (see the recent fuel can mounting discussion). My upper bracket is consistent with the design of various fuel mounting solutions that have so far not failed after many miles and years on rough roads (granted that "so far not failed" is not a great measure of success....).

Longhorn,
Many thanks for the info on the threshold and keeping me from making a big mistake. I suspected it was more than just a structural member. I need to rethink the lower bracket, assuming I move forward with the current design.

I've had no luck in my attempts to find photos or other information explaining how the sandwich floor pack is constructed. I'll call FWC if I don't hear from anyone on the forum.

Jeff

 

[DavidGraves]

Jeff

My 97 Toyota T100 bumper has carried our box for years in Baja and a lot of crap roads in the Northwest.

Bolt a fairly stiff plate of metal (I choose aluminum ) to your bumper.....truck can still easily load camper....bolt box to plate.

It works pretty well...three bolts remove the plate when camper is off.

Expedition Portal will think you are an Austrailian outback hero.

 

[Redfish]

Dang. Outback Hero! That's the most convincing argument yet.
Do you have a picture you can send me or post? I'm not quite sure I understand how you mounted your box.
Many thanks.

 

[So Cal Adventurer]

I am a little late to the party, but reading through the comments.

Food for thought...

I hear some bracing to the bumper idea. If you mount the box to your FWC and brace it to the bumper, i cant see how you WONT have issues.

The frame flexes separately from the bed of the truck. Bumper = attached to frame

my .02

 

[PackRat]

The bumper mounted frame will need some kind of upper arm to help with vibrations so I would check where the tailgate would normally close to get a fore/aft surface to bolt it to. Then a strap that bolts to the rear corner of your carrier would be possible.

As noted, steel will be too heavy so aluminum would be the way to go.

 

[PaulT]

Anyone looked at this option by Craig333 post #87?
http://www.wanderthewest.com/forum/topic/14461-fuel-cans/page-9

Paul

 

[Redfish]

Paul,

Thanks for your suggestion. I studied that thread pretty closely, plus other threads dealing with mounting jerry cans and other things directly on the camper. My box is long and skinny, so assuming we're talking about a camper mount, I need some kind of lower bracket attached to the camper to support the box. I believe the upper bracket will bear most of the weight.

Here's another photo/drawing showing how the upper bracket will be bolted to the frame using existing mounting points (from left to right, grab handle, step, and jack plate, 7 through bolts total). The bracket in the photo is a bit too high, but you get the idea. I feel pretty good about the upper bracket.

I think the box has to be either attached to the camper or to the truck, not both, as per So Cal's comment, but I may just have a limited imagination.

Jeff

 

[patrkbukly]

For whatever it's worth,
On my F250 I cut a milk crate halfway up so that it is half deep and mounted this to my bumper. This allows for the cassette toilet door to still swing open. It is durable enough to have our camp chairs sitting in the crate and then bungied higher up to the camper.

I will try and post some pics.

And yes I would rather a better look than a milk crate but the damn things are durable and weatherproof so works for me.

 

[Redfish]

Photos would be great. Thanks.
Jeff

 

[ntsqd]

Aluminum is a double-edged sword. It is less dense than steel, but it is also less rigid. By the time you add enough thickness to it to make it as rigid as a thinner piece of steel they weigh nearly the same (I've done that design study several times over the years). If you have design skills and can design the assembly's geometry to make it rigid (rather than relying on it's material thickness), that is where aluminum will save weight.

For the tire carrier that I designed and built for our truck I used the tail-gate pivots and one of the tail-gate latch posts to support the whole assembly. Looks like the thread was one of the d-base victims. A couple in-process pictures:

Just because the bumper itself won't support the load doesn't mean that you can't employ either it's support brackets or it's mounting bolts to support the load, without resorting to a whole new bumper. On our 4rnnr the rear bumper and its supports are basically tin foil, but the OEM trailer hitch right behind the bumper is significant and I have designed a tire carrier that will become part of that structure.

 

[RicoV]

Nice work!