Calculation for M416 Lid Weight


I would like to order lift struts for my M416 build. Unfortunately, for many reasons I am unable to remove the lid and weigh it. I was able to get one measurement that, with your help, may allow a very close estimate for the lid’s total weight.

The lid is hinged on the tongue end of the trailer. The tailgate end of the lid weighs 90lbs when lifted just 2” off of the top lip of the M416. The lid is 74 5/8” long and 51 5/8 wide. Is there a calculation to get close to the total lid weight for the purpose of choosing the correct lift struts? Obviously, it takes 90lbs of force to lift the tailgate end of the lid.

Thanks for any and all help with this.


Sounds like its total is about 180.
You can verify the theory by using a yourself or a known weight, a bathroom scale and a few wooden blocks.


New member
Worst case is the beginning of the lift. If it takes 90 pounds of vertical force to start the lift, you can calculate the vertical required force at any point using rectangle triangles ratios depending of the distance between the hinge and the tail gate end. The closer you will get to the hinge, the beefier your struts will need to be, but they will also be shorter. Then you use trigonometry to determine the force (vector) needed at the angle your struts will be to start the motion. You also need to calculate the lengths needed at full extension. I would usually do a few iterations based on the model selection available.

Its hard to explain, but easy to do.

I found examples:

In your case, you are working with a known required force at a specific point. Verkstad is right, you are lifting completely at one end, then your total weight should be close to double (180 ish)
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