Bolt down system for truck canopy

[david85]

It took a long time to find the exact canopy I wanted. Cab height, neutral white color, and aluminum base plate, instead of wood-core fiberglass. The roof is also cored with something that makes it stiff enough for me to walk on it. Not bad.

Unfortunately, that aluminum base plate proved flimsy and a few pot holes on the dirt roads quickly caused some damage to both the canopy, and my truck. Basically the bouncing and flexing caused the base plate to rip around the hold down clamps, allowing the front canopy corner to start bouncing.

I didn't want to add new holes in the truck so after a few months I had a brainwave. The rear tailgate latch uses two bolts on the bullnose era. Those bolts thread into a floating steel plate that's captured by some sheet metal tabs. This allows for easy adjustment and is very common on most vehicles. The door hinges of these trucks are adjustable in the same way. Anyway, the ends of these two bolts are long enough to just barely get a nut on them. You might be wondering how I intend to tighten a nut inside the rear corner stake pocket of the box. Well, you don't.

Instead, I needed a steel plate that was threaded to the right pitch and with two properly spaced holes. Since I'm a filthy pack rat, I still had the original box for my truck, What's left of it, anyway. And that meant I had two perfectly ready made plates.

I welded a threaded rod onto the plate, and bent it so that it came up roughly through the center of the stake pocket. This turned out pretty solid. Aside from being a much better hold down system, it also meant that the canopy can't slide around either.

It was easier to fab up something for the front pockets. I used some steel channel scrap to fabricate a long "L" bracket. This hasn't been road tested yet, but I'm sure it will hold up better than the usual canopy clamps I've been using up to now. Once finished, I panted it with zinc rich marine hull primer.

Building these components took a couple afternoons of work. Prepping the canopy and accurately drilling the holes took another whole day.

 

[david85]

Here's what they look like installed. The only bad news here is I don't think this will work on trucks later than 1986, since the latching system was changed.

 

[david85]

Here's the canopy base plate getting prepped and drilled to fit. I'll get some more photos later to show the end result.

 

[lotzagoodstuff]

Nice fabrication work Kudo's to you for being a packrat and saving the old bed off your truck. Nice write up/documentation too.

As an OBS with canopy owner, my view is pure jealousy.

 

[Jesus Freak]

Great job! I'm always looking for the right topper as well, but I want a janky aluminum one. If it's too pretty it'll mess up the look of my truck.

 

[rreegg]

Looks super solid, nice. The bent threaded rods look like they're gonna start crawling away or something.
Slightly surprised the aluminum base was warping due to road conditions but always a good idea to beef things up. Better than c-clamps..

 

[The_Josh_Bear]

Nice work! I love it.

 

[david85]

Leak tested it today. No water coming through at the bed rails but some of the windows will leak, if enough water overwhelms the tiny drain holes in the extruded window frames. I might be able to seal them up better but I'm pretty sure normal rain should be no problem as is. Rainy season is almost here so I'll find out soon enough.

The canopy door also comes down low enough to lock the tailgate at the same time. It won't keep a determined thief out, but better than nothing.

And lastly, I managed to salvage the aluminum tailgate cap from the old bed. It was badly mangled but after about 3 hours of straightening (yes, really) its good enough. If it wasn't for this, the new paint on the tailgate would quickly get worn off by the canopy door gasket gasket. Dust from the road is surprisingly abrasive so I was only using my spare "junk" tailgate up to now, and it wore through to bare metal in a few months.

 

[gandalf]

That's good work. It should serve you well.

However, I have a single reservation. Our truck beds flex quite a bit. Its the way our trucks are made. I've seen one rear corner of my truck rise and fall 7 inches while the other side was stable. The frames are that flexible. This is usually fine, until you put a shell/cap on the truck. When there is a shell/cap, you're asking the shell/cap to flex because it is attached so firmly to the bed rails. This can have bad results. This happens most in off-road rough terrain.

I've had 2 shells on 2 trucks. The first, bought second hand, had stress cracks at the rear upper corners. I pulled it off the truck when it arrived in Maine. My second shell, also second hand, at least, was given me by Calvin's daughter after he passed. This truck, pictured in my avatar, is 2 wheel drive and doesn't leave the pavement. The flex does not cause a problem.

 

[david85]

Yup, flex is an issue. I'm hoping the fiberglass will be able to move with the bed. I did try flexing the truck once to test articulation, but never got to the point of actually lifting a wheel (there's a pretty big ravine on the other side of that rock!). Front and rear stabilizer bars are currently disconnected, to allow for more articulation, and less twist in the body. I'm still looking to try and stiffen the frame some day but can't settle on how to do this. Maybe some intermittent boxed portions? I'm not ashamed to admit losing sleep over that flex dilemma. But then I remember how long these frames last in their flexible form and start worrying about creating stress points that might crack.

I didn't quite catch the top of the box in these older photos, but if I had to guess, there is less than 7" total flex within the box itself.

 

[DaveBen]

The pick-up bed is a box and it is unlikely to twist or bend which would damage your shell. I had one on two 4X4 trucks for years and never had a problem with the shell.