Bed subfloor/framing?

[BR3W CITY]

So I'm curious if you guys think its even worth it. I've gone through a few beds in my truck and want to finally make the switch to an aluminum bed floor. Plan is to ditch the stock cross braces and make a subfloor/frame deal to support the alum plate/sheet.

Due to the battery and fuel cell, I'll be making the floor modular (again). It doesn't need to haul anything, but needs to hold the weight of a set of wheels, or a dude standing in it. Steel 1/2 sq structural tube was my plan to keep it light and strong enough, then skin it with the alum.

I posted a video on the topic as well.

You Tube

So I took a couple photos and overlayed a few lines in p-shop. I might end up having to do something way more complicated, but only having to support 300ish pounds shouldn't be too bad.




The red bar is where the thicker tube bridge would be sitting, as I'll be changing to coilover, but thats a different topic for another day. What do you guys think (aside from the ugly drawing). The frame and alum bed should still be functional, but allow me the modular access to my diff, prop valve, ujoints, fuel cell, battery, and fuel pump all from the top. Maybe I'm being optimistic, but I don't see why it shouldn't work. Aside from that, I'm hoping to net a weight loss over the heavy crossbeams and my 1" TREX bed.

[Super73]

Extra weight.... My thought.. Plus, I get a lot of positive comments on the rubber racing stripes my cab receives with the open bed...

[BR3W CITY]

Hahaha, well, I need to carry my race gear and my camera rigs for track days. Its REALLY annoying using 10 ratchet straps to hold my stuff (notice the grey tub in the second pic lol)

[HAULIN' IT]

1/2" square tubing is not near strong enough, however in your video it looked like you are holding 1" tubing? Kinda hard to tell with the lens making it distorted.

Also you need to think about the span you are going across. That One foot piece around the fuel cell is NOT the same thing as going 4 feet across...Yes it may be made out of the same material, however the distance is a factor when carrying weight. The height & thickness of the material is what gives you strength in what you are doing...the width of the material is really of no concern. I do feel 1" tubing would be fine for the limited weight you are carrying & would provide a reasonable surface to put your fasteners in to hold the aluminum. I would suggest heavily painting the steel structure & the bottom of the aluminum before you attach the two. Aluminum will corrode when mounted against steel.

The area going over the rear could be made out of 1" angle due to the rigidness of the area...would still give you the vertical strength & a surface to attach your fasteners. Same thickness material would be half the weight...just a thought.

I really don't think the "modular" idea is worth the bother...It would be easier to jack up the truck than fool around removing/installing a bunch of rivets & reaching down through a hole. Much of a project (coil-over install) it would be easier to just remove the bed, Just my opinion.

Also you mentioned going to coil-overs...make sure you allow for that clearance to the backside while building your "dogbox roof", they take up more space than may be realized without having them in place. Lorne

[Marv D]

I built mine out of 3/4" steel square tube and 0.065 aluminum. NO WAY could a 180 pound man stand in it and not bend the CRAP out of the steel spans. I can carry a 20# bag of ice or whatever in the corners, but you are going to need some serious steel strength like Haulin-it is saying to carry much weight.

Sorry don't have any real 'good' pictures of the bed support or with the aluminum in place.

[tinydb84]

Here is what I am doing (obviously not done). Not really planning on hauling anything but I am sure it can hold a set of wheels without a problem. I'm not racing (raising the floor for clearance). Its mostly 1x2x.083 with a few pieces of 1x1x.095. The pieces bolted to the bedsides are .120 wall because thats what I had when I started. I am going to get rid of the stock floor once it is all built. I would go with the .083 if I did it again. I can weigh it after its built if you want.

[BR3W CITY]

Thanks for the responses guys. I was holding 1/2" in the video, but I have (and can always just order) 1" or a few metric sizes.

Finding the balance point is the main problem, everything is either a little too thin (but light), or strong but not much lighter than those stock sills. Why oh why did I have to uses my truck as a prograndstreetdragtouring vehicle? Having truck schizophrenia is tough....I wake up not knowing who my truck will be that day.


Haulin it- I have to make it at least 2 sections because I'm not comfortable with not having access to the battery in an emergency situation. I've got pretty serious damage to my back, so being able to work-down instead of work-up is helpful for me. I'll end up buying a topside creeper for that same reason.

Tiny- looks like you've got the closest to what I'm thinking. If you get done soon and it isn't trouble, I'd be curious what the weight came out at.

[RocketChevy56]

I used 1 1/2" square to hold up the diamond plate bed floor we made. The crossmembers were rotted and a real mess. 1 1/2"x1/8" square supports going to the front to tie in to the existing bed frame (Reinforced the existing bed areas) and 1"x3" rectangular (also in 1/8") running across. This is no race truck, but the weight of the bed is sitting nice over the wheels and made for some decent traction.

I understand this is not really ideal for your situation, but maybe you can get an idea or 2 stirred up. I'd love to see some modular floors you or anyone have done. I'm getting ready to raise my bed and would like to do something similar. Can't wait to see what you come up with!!

[tinydb84]

Not finished for my use but for what you are looking for it should get you pretty close.

I welded it all up but didnt bother to take a pic.

Came in at 57lbs. Probably could be a few pounds lighter. The outer 1x2's were .120 wall (had it when I started). The rest is mostly 1x2x.083 the 1x1 in the center is .065 wall. If I did it again I'd use all 1x2x.065. Let me know if you need any more info.

[BR3W CITY]

Thanks for the update man. Is 57 lbs the frame only, or frame + floor?

If I go 1" or 1.5" sq tube on a slightly more sparse floor (since my huge tubs take up 1/3 of the middle bed), I'm thinking I can probably come in 8-10lbs less. Even more if your weight included the floor, as the 1/8th plate is pretty dang light.

I should be getting out to my metal supplier this week to at least get the framing stuff. I do still have some hangups on my setup for the rear suspension bridge, so this may get done in stages.

[tinydb84]

Just the frame. I think you could get even lighter if you tried. 1x1.5x0.83 and attach to the side of the bed with tabs instead of the tube. Like 4 cross bars and make the rest out of wood.