Gas strut mounting position advice needed

[VanIsle_Greg]

Hello All,
I am looking for some advice, and some of your personal experience. I am about to mount 2 x 100 pound gas struts (lift shocks?) to assist with lifting my lid and RTT. I am going to be adding a set of 6x6 blocks to the inside of the wood lid, then using some stainless bolts and washers to mount the struts. That part I have sorted out... where to mount them, that is the question of the day!

here is a couple of pics of my lid on the trailer

I think the bottom at the tub side will be mounted to the hinge side of center while the top will be mounted more towards the latch side at an angle. I know there are a TON of M416 and CDN M101 trailers with lids...anybody care to share their experience and some measurements (maybe a photo)? I do not want to drill holes in the tub and in the lid only to find it doesn't work because of the angles.

Thanks all!!
Greg

 

[jeepfreak81]

IIRC Mine are centered on the lid, and then about 7" from the trailer side. (opening side)

 

[veetee]

Depends all on various parameter, such as weight of the lid, gas spring strength, base length and extended length of the spring, and position of the fixing poinys on the tub and lid.
There are some calculation tools online:

http://www.bansbach.de/com/gasfedern/online-calculator-3.html

http://tools.gerani.nl/gasveer/gasveer.html (this one is my favourit, but in Dutch language. Maybe you can use google translate)

 

[Woods]

From a post that I did HERE

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...culator-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.

 

[sixbennetts]

I'd jam a wooden dowel through both holes in the end of the gas strut and clamp the dowels to the lid and trailer body with Vise-Grips or C-claps, padded of course so you don't mar your finish. That way you could try a few different positions to see what you like.

If you're adding stuff to the roof of the trailer later, you can bungie cord some weight onto it now just to simulate that weight.

A cheap Yankee told ya that.

 

[Ken Miracle]

Very nice lid, I have never seen construction like that on a home made lid. You must have bought it. Could you supply me with any details on it.

Thanks in advance,
Ken
MiracleAvn@aol.com

 

[VanIsle_Greg]

Wow...excellent advice and links, much appreciated all. Good idea on the scale to weigh the lid. The RTT is now mounted, so everything going up there is now up there, my guess the point load will be in the 100 pound ish range? I can lift it with reasonable effort now, struts will help a lot.

I picked up a set of the longest ones I had access to at a local supplier. These are around 30-36" from memory. They say they are 100#, but I cannot find any information on them online by referencing the part numbers? Anyhow, it I calculate that I need longer or stronger struts I will order what I need. These were SUPER cheap and NIB so I don't feel bad selling them online cheap.

I will have a look at this tonight and see if I can come up with a good solution and post my thoughts before I drill (for peer review).

Thanks all!

 

[VanIsle_Greg]

Very nice lid, I have never seen construction like that on a home made lid. You must have bought it. Could you supply me with any details on it.

Thanks in advance,
Ken
MiracleAvn@aol.com

Hey Ken,
Dont think I could make this myself? heh...well, you would be correct. I had a friend design and make it for me...and he is a craftsman. He is the owner of Trekken Offroad here in Victoria BC and makes all kinds of chuck boxes, truck boxes, etc. He worked with me on the basic shape, and ran with the design himself. It is amazing, and pretty light too. The lid sans tent weighs in and around 50# and is strong. Wife kids and I on the roof in the tent, no problem! He estimates it can safely hold 600-700# and I believe it!

Details... not anything other than pictures, and what is in Mike's head! lol

 

[hesterj]

Hey Greg,

I just ran across this missed thread. On my m416 lid I was also reluctant to drill a bunch of holes to get the formula correct.
What I ended up doing was install a 1x2 square tube at a estemated angle to the inside of the tub. The tube was drilled with mounting holes every one inch down the face of it. This way, no matter the length or angle, the struts could be dialed in to the correct spot. (no pic's here cause me and this iPhone don't get along to well on portal)
You have probably already done the strut mount by now. post up a pic if you did. If not, I posted some pic's of it on my trailer thread on jeepforum. Hope it helps.
The trailer is looking great!

 

[VanIsle_Greg]

Hey HesterJ,
Actually...I havent done this yet. I scrambled to get the stuff done I "needed" to get done for my trip last weekend. It was a shakedown trip and a "what do I really need" trip. What I came up with... I need an internal (small) water tank with pump and on demand hot water!! My buddy on the trip Mike has that in his trailer, and it is the cats ********.

I will take your advice and do some testing. I pretty much have where on the lid I need to mount the struts, the tub...not so much. Played with the online calculator and found I really needed some correct measurements before I continue to get it right. Pics when I get the formula in testing.
Greg

 

[Ozarker]

Thanks for the reminder, I'm making a note of that. When building the lid, build in a 1/4" to 3/8" plywood square about 4" square on the underside with the hardware for the struts attached to the square, then epoxy into the bottom of the lid. Otherwise I'd have to epoxy that piece on after the build and have to remove any paint for a good bond and paint again. Same for the other end too or bolt it in on the side. The additional material will keep the strut attachment from cracking through, cracking the paint job on top, especially if you have additional weight on the lid when you open it.

You also have some very nice ribs in the top, so you could mount to one at the side, you may need a different struct attachment. Nice trailer!

 

[DonBeasley]

Don't know how much help this will be but the struts are dead center on the lid and about 8"-9" in from the side with latches.

 

[VanIsle_Greg]

Don't know how much help this will be but the struts are dead center on the lid and about 8"-9" in from the side with latches.

Nice Don... what does that lid weigh with the RTT up there, and what weight are those struts rated for? I was contemplating setting mine up like that or more vertical, cant decide yet? Also, how much does it assist you in lifting the lid with them like that? A lot or only just some?

NICE trailer!!

 

[DonBeasley]

I have not taken the exact weight of the lid and tent but both are at least 100 lbs. each. The struts are 175 lbs each. They do help with the lift. Hard to start, mostly due to gasket making a tight seal. Once that breaks loose it goes up pretty easy. Not sure my wife could get it started but once it is about 8" up, it is easy after that.

Thanks for the comments on the trailer. Still working on it.

 

[VanIsle_Greg]

Yeah my lid is hard to start as well...that 4 person RTT is pretty heavy up there. I am hoping that the struts I have are good enough. I can barely compress them by hand, they seem to be rated at 100# each but I cannot confirm online as there is zero data available on them by serial and product numbers?

If not...at least I will have all the mounting done and it will just be a strut swap.