M416 lid questions

GFA

Adventurer
Hello fellow adventurists! A few months ago I picked up a nice 1989 M416a1 trailer in decent shape. It needed a new floor but otherwise is mostly rust free. I have modified the lunette setup as I don't need surge
brakes and want a pivoting hitch setup like the max coupler.

Now that I'm working on the lid I have a few questions. The biggest being which way to hinge it. I see some hinge it at the front but most seem to do it from the side. It seems the if you hinge it at the front, it would work best with a RTT that's opened but maybe it doesn't matter? I won't be putting a RTT on right away but might in the future, for now we're loving our 10/14 Kodiak canvas.

Secondly, how do you figure out what lb rated struts are needed and how to figure out the placement of them.

Thanks
SB
 

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Woods

Explorer
Looks like some nice work being done here.

I think hinge design is determined by how you're going to use your trailer. I have a galley at the back, so a side hinge didn't make much sense. If you don't have any specific need driving how to hinge, it I'd default to a side hinge, as that's what AT does.

Strut design is a little tricky. Of course, you'll first need to determine the angle to which your lid will open. I'd then look to see what gas springs are available to you. I'm using gas springs that are 30.1" long with a 13.8" stroke. Knowing this, you can determine positioning of the gas springs. Positioning is two different trade offs. First being the starting and ending lifting force that is put on the lid. For instance, if your gas spring is parallel to your lid, then the starting lift force is zero. The end load is more important as it's the force that is required to hold the lid in the up position. You'll want to use an ending force that will hold the lid open and position the gas spring so the starting lift force will not automatically open the lid. To make matters more confusing, the gas springs lifting force changes with temperature and age. Gas springs by nature wear out and the warm the ambient temps, the more force they apply. For every 18 degree change in temp, the force changes by 3.5%.

Here's a link to a gas spring calculation program: http://www.bansbach.de/com/gasfedern/online-calculator-3.html Not the easiest beast to master...

I digress - You can avoid a lot of theory by using a bathroom scale and some pieces of wood to determine your gas spring requirement. Use two sticks, to represent your gas spring compressed and extended lengths. Use these to make an initial guess, as to what the gas spring mount locations will be. Take a long pole and simulate the positioning of the gas springs, when the lid is in the full open position (best done in the middle of the lid, between where the gas springs will mount). Cut the pole so you can put a scale under it, while bracing the scale perpendicular to the pole. This will determine the minimum force required to hold the lid open. Once you have attained the gas springs, you'll be able to play with different mounting positions. BTW, I have a pretty light aluminum lid and I use two 30 lb. gas springs. I'm in process of building a larger (heavier) lid and will need to change to stronger gas springs.
 

Pikeman

Adventurer
Generally speaking they hinge the lid on the side and place the hinge for the RTT on the same side. This way as you lift the lid it partialy closes the RTT without having to fully close it. Making inside the cargo box accessible even with the RTT deployed or opened up.
 

Hill Bill E.

Oath Keeper
Generally speaking they hinge the lid on the side and place the hinge for the RTT on the same side. This way as you lift the lid it partialy closes the RTT without having to fully close it. Making inside the cargo box accessible even with the RTT deployed or opened up.

That is how I did mine^^^ Works great! (as long as the wife isn't napping when I open the lid! :elkgrin:)

trailerCJ009.jpg



Nice fab work!
 

GFA

Adventurer
Thanks for the how to woods, that helps a bunch

Hinging it at the side makes sense now thanks to hill bill e's pic. My only concern now is my chuckbox we just finished, it was kinda designed to be placed and lifted out of the rear. It might be pretty tough to lift it from the side. I guess I'll just have to load it up with stuff to see how hard it'll be to lift.

I'm sooo close to cutting in a tailgate... It would solve all of my issues.

SB
 

Hill Bill E.

Oath Keeper
With a little ingenuity, you could fab up some 'pinned' hinges, allowing you to open the lid from either the side or the end.

By using removable pins in the hinge design, they act either as a hold down, or a hinge.

ie: Pull the pins from the side(s) and open the lid from the end.

When the RTT is deployed, pull the pins from the front hinges, and open from the side.

I designed my first lid so it opened from either end. But I discovered that with the 4x6 box size, I could load/unload everything from the side very easily.

Even my kitchen box.

Some folks build a table that sets over the fender, since that would prohibit loading/unloading from the side, I built mine to fit across the tail end of the trailer.

trailertable008.jpg


Sorry for the fuzzy pics, my phone doesn't like the lighting in the shop.

:coffeedrink:
 

Vince1

Adventurer
If you plan on adding a RTT, then your strut lifts need to be oversized accordingly. This leaves the problem that it will open too fast or be difficult to close when the tent is not used. There are powered hydraulic lifts that will work no matter the load, but they rely on onboard power. I ended up ordering 3 sets of standard lifts until I got the balance right, but my lid is super-heavy as we used too thick a gauge of steel. I plan on re-skinning it this Spring. Luckily, I saved the lighter strut sets. I used these hinges, hinged on the drivers side, and reinforced where they attach to the tub. Good thing is they are greasable and have bolt pins so lid can be removed when used for material hauling:
Www.northerntool.com/shop/tools/product_200306309_200306309

The drivers side hinging allows me to access the tub roadside to grab something without standing in traffic; something to consider if you pack a fridge back in your trailer.
 
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GFA

Adventurer
Not too much to update, too busy trying to make a living...

I did play around with strut positioning. I really wanted it to be able to easily be loaded from the rear instead of reaching from the side all the time. My chuckbox was the main concern as its close to 100lbs loaded. My setup allows me to lift it over the rear without the struts being in the way.

Hopefully I'll get some sheet metal bent for the frame this week and send the trailer to the blaster. My goal is to have it trail worthy by the end of the first week of April.
 

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GFA

Adventurer
Finally had a chance to get back to work on the trailer. The lid is finished, two 100lb struts allow it to be lifted with 2 fingers

Tub and frame have been blasted. I primed and painted the frame myself, turned out pretty good. I do wish I had used a better paint though, the rustoleum is still soft 2 weeks later

The tub and lid went to the paint shop today for a coat of rescue green to match the JK. I'll have it waiting for me to assemble when i get back from a week of fishing the backwaters of florida's Everglades.

Next thing to do is convert the axle to 5 on 5 brake drums to be able to run factory jeep wheels to match the JK but that'll have to wait till I take it on a trip or two...

Maiden voyage scheduled for may 5th for a trip to cape lookout, can't wait!!!
 

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Woods

Explorer
Looks VERY nice.

Yeah, I've been pretty bummed on the performance of spray paint. I wonder if it has to do with the paint we used today, vs paint that was available in the past.

Had never heard of Cape Lookout. Just Google Earthed it. Looks like a good time for sure.
 

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