Bed Stiffener Alternative Solution???

I asked ChatGPT to condense and simplify your reply

Every bedrack and topper you buy can handle its own weight and the weight of what it carries without forcing the bed of your truck to spread out. But driving (movement) can distort the sides of the truck bed.

To explain this, we need to understand two concepts: static load and dynamic load.

Static load is the weight of something when it's not moving. Imagine you're loading your camping gear onto the truck. Let's say the total weight is 500 lb. That's a static load.

Dynamic load is the weight of something when it's in motion. For example, if you're standing on a scale and jump off, the scale will briefly read a higher weight than your actual weight due to the force of your jump. This extra weight is the dynamic load.

When you're driving your loaded truck on a bumpy road, the camping gear and everything else in the truck bed moves up and down. This motion transforms the static load into a dynamic load. This dynamic load, in turn, can exert lateral (sideways) force that can damage the sides of your truck bed.

Another important point is how forces translate in objects. When a force is resisted at a spot that's not aligned with the center of mass, it can result in forces in different directions. For instance, when the camping gear moves up and down in the truck bed, some of the downward force can turn into sideways force.

To counter this, some people use bed stiffeners. However, how effective they are depends on their design. For instance, a bed stiffener with a small angled piece of steel near the corner would be better than the truck bed itself because it alters the stress concentration and increases the distance between the point of inflection and the resolution of the forces. But a more mainstream stiffener might be even better, as these are designed to resist bending forces.

In conclusion, if you're putting a rooftop tent (RTT) on your truck rack, consider getting bed stiffeners. The weight above the truck bed floor can put a lot of strain on the corners of the bed. However, it's important to note that this advice is based on basic principles, not a detailed analysis of the situation. Until a thorough analysis is done, it's hard to say exactly what type of bed stiffener would be best.​

 

That is surprisingly good!

My only change would be that if you are putting a topper/bedrack/rtt on your truck bed, then you should definitely get bed stiffeners.

There are a lot of products for offroad/overland-themed Tacomas that are nonsensical. Bed stiffeners are not one of them.

 

It's eerily good at everything

I just like the extra tie-down points lol I'm also not going to deny that the way my truck is evolving, a bedrack is not too far off. Just waiting for my kids to be able to proficiently wipe their own asses.

 

Wow. great response.

This should put any argument to bed of whether there is ANY benefit to bed stiffeners...how much benefit will be subjective to each individual and their setup/purposes for the truck.

 

An even simpler breakdown of the difference between static and dynamic loading might be this:

"static" load in this context is application of a constant 1g downward on the gear/rack/bed/frame/suspension/wheels, just the vehicle carrying its own weight. This load is easy to predict, design for and assess the effects of.

"dynamic" load involves application of load with magnitude and direction which can vary widely depending on the environment and usage of the vehicle, and the more uncommon the use of the vehicle gets the more difficult it is to anticipate/evaluate the effective load directions/magnitudes or to design for such loading. Street driving involves a fairly well defined and predictable range of accelerations and is accounted for in the factory engineering, trail driving is where it can get chaotic and more difficult to guess accurately (and where the working loads can get outside of what the engineers at Toyota designed the truck to do)

It's hard for me to tell if that's really simpler in lay terms, I've been making a living doing structures analysis on fighter jets, rockets, spaceplanes, and satellites for 26 years now, and it seems fairly straightforward (in that the whole question gets somewhat complex once the truck leaves the pavement) to me.

 

Yes. Yes, it does.

 

After years with a cap and running around lots of terrain, the old truck bed-sides had bent outwards. When I finally took the cap off to refurbish the rear-view mirror aided in seeing the effect over time, which necessitated the buying of stiffeners - aka spending more Taco money.
Yes, they help. I'll toss my bit for the side of getting the stiffeners.
Great tie-down options, and they seemed to do the trick of bringing the sides - close - to 90 and keeping them there.
Don't try to rig something that will only serve to make you uncertain and add to work load.

 

I'd have to say that I don't think your answer is simpler in lay terms tbh. You are coming from a really experienced perspective, and your simplification misses out on the smaller bits that are necessary to help paint the picture for those who don't do math all day, or who don't understand the difference between things like stiffness and rigidity.

Re-reading the ChatGPT synopsis of my original italicized and bolded post, I realize that it too removes too much of the nuance, allowing for an incomplete picture to be painted for those who are interested in learning more, but aren't engineers/mathematicians/etc.

Also, I would not predict an issue with a Tacoma, unencumbered with overlanding gear or other bulky modifications, to be able to withstand off pavement driving. It most certainly is within their design parameters, their vehicle testing centers prove it. Sure, your bedsides might migrate away from one another even if you don't have a topper/bedrack, but it would take a looooong time to experience the same deformity that a Tacoma with an RTT would experience in a year or two of offroad driving. The moment we start affixing things to our trucks we have left those initial design parameters behind, and the chaos begins.

 

Nobody designs for that....

 

I kind of suspected that might be the case. I'm so steeped in it at this point I can't go back and re-read things from even the perspective I would have had fresh out of college; since I majored in Aerospace Engineering I knew a lot more about aero/thermodynamics and orbital mechanics than I did about structures back then, these days I can only remember basic fluid dynamics but can practically visualize what FEA stress plots will look like on a CAD model of a bulkhead.

Without a topper/rack mounted, you'd have to be using the rail tiedown system to strap in heavier stuff like dirt bikes or big-ticket "glamping" gear to get much load into the upper bed on any kind of terrain. Since the cab and bed are just riding the frame, the sides of the bed aren't supporting much more than their own weight (and some of the tailgate) until something gets attached to them.

With enough math and fabrication, there's probably some way to design a replacement tailgate and modified latching system that would let the bed transfer load like a 5-sided "bathtub" instead of being a box that's missing two adjacent sides, which would hypothetically eliminate the need for gusseting on the rear corners (and at only 6-8x the cost of the currently available solutions). Or if you were willing to put in a taller version of a "decked" drawer system and lose use of some space in front of the wheelwells (on the 6.5 ft bed anyway), permanently bolting a plate with some "waffle" or isogrid stiffeners on it to the entire length of the front and side rails (like a hard tonneau that can't be opened) would tighten the whole thing up structurally in exchange for 80% of the utility of having a truck in the first place. Half of engineering sometimes is separating the useful solutions from the ones that just cause new problems...

 

I guess why don’t other trucks have that similar issue and just Tacoma. I have a topper,rtt,camping gear all totaling 400-500lbs for three years. Camped about 50 times, drove off road a half the time. This weight is always in my truck. Maybe my beds will fail in a few years who knows. Again why is this issue only with Tacoma and not prevalent in other trucks. I guess it’s just lacking evidence to why it’s needed. A few here have said their beds were damaged. And as some said here it’s really only needed in some exceptional situations which most are not doing. I understand the logic some have posed here and it does make sense, but that would hold true for other trucks across the board.

 

If you look you can find examples of this kind of failure in other trucks but since this is a Tacoma forum we talk tacos and their issues. I think it’s also the case that Tacomas represent a vast aftermarket overcrowded with buyers looking for someone to “just take their money”. In my case my previous trucks had welded lumber racks that needed no additional lateral stiffening. I now use just a shell with bars but occasionally still overload the roof bars and shell substantially more than you and the bed supports seem to have been up to the task.

 

My assumption, and we all know what they say about those, is that the difference is the composite bed. There is a lot more steel (or aluminum) in most truck beds tying the bedsides and floor and front of bed all together as one structure. The composite bed does have a metal structure at the rear, which from what I've seen on here in the past can crack in the general area of the Red dotted line with the red arrow pointed at it (which is what the bed stiffener supposedly helps to mitigate. The green arrows are the metal structure area I'm speaking of.




Not much to the bed sides themselves.

 

It appears there is very little material there holding on to the bed stiffeners if I am seeing this correctly. I would think if the bed is going to separate it will do so regardless of the bed stiffeners. The structural integrity would be the strength of the top and bottom not where the bed stiffeners are installed.

 

The bed stiffeners strengthen the metal structure so the weak point doesn't take all the stress. It creates a gusset between the lower horizontal metal structure and the vertical metal structure, as the weak point is where the two meet.

 

where the bed stiffeners mount is where the composite bed overlaps the metal reinforcement, and the corner that it gussets is the red dotted line corner in the pic where he stated most documented failures occur. So a stiff piece of metal reinforcing that corner would prevent it from failing sooner, if not altogether.

The issue isn't that the bed is getting crushed, but that it is bowing outwards.

 

I have an ARE CX-HD top. It has a 550lb load rating. I have put a lot of heavy stuff up there. I put bed bars, extra topper clamps and bed stiffeners on when I got my truck new 5+ years ago. No problems and no cracks yet.

 

You’re misreading the stress and what the stiffeners do. They grab the under bed gate cross bar and hold the bed walls at 90 degrees so they can’t roll in or out under lateral load. They can also provide more vertical loading at the rear corners. The web connected to the surface they bolt to on the sides just provides shape to the inner and outer surfaces and not a whole lot more. It’s not the only weak point in these trucks but it’s gotta be the easiest to fix.
Just the other day I saw a dcsb with lumber racks on the freeway with a kink visibly flexing in the middle. The front of the bed was jammed into the cab below the rear glass and the front corners of the rack had foam taped to them since it was riding on the roof. That same rack had 4” clearance at the back of the cab. It was seriously disturbing seeing the truck wiggle in the middle as if it was ready to let go like Herbie the love bug. These are just slightly enlarged light trucks, not heavy duty anything.

 

I don't carry anything on top of my box, so it's a mute point for me.

As long as nobody steals my tailgate...