Lid mounted shock
- Thread starter syke
- Start date
Poorboyota26
Adventurer
these guys have all of the hardware and everything! Many locations to ship from too.
syke
Adventurer
Looks good. Thanks
jcbrandon
Explorer
McMaster-Carr has got a great section on choosing gas struts and a huge selection of them and the mounting hardware:
http://www.mcmaster.com/#gas-struts/=24x7ta
http://www.mcmaster.com/#gas-struts/=24x7ta
ntsqd
Heretic Car Camper
Those gas springs that I have purchased came from mcmaster, but another vendor is Austin Hardware.
http://www.austinhardware.com/categoryPage.cfm?CatID=6&CatName=Gas Springs
I've purchased other parts from them, just not any gas springs.
http://www.austinhardware.com/categoryPage.cfm?CatID=6&CatName=Gas Springs
I've purchased other parts from them, just not any gas springs.
DaleRider3
New member
Nice find - they have a location near me and have lots of other useful parts like drawer slides and latches that should be good for customizing my conqueror.
Poorboyota26
Adventurer
:victory:
syke
Adventurer
Thanks for the help and the links. I am sure I will be able to find exactly what I am looking for. With that being said I have another question....
How do I figure what weight of shock I will need? I understand the collapsed and extended measurements, that's no problem but the lifting capability is in question.
I have roughly a 100lb lid plus a 125-150lb RTT. So call it 250lb to be safe. Now that is hinged on one side so the shocks wont be bench pressing 250lb. Do I cut that in half? I plan on using 2 shocks just so the lid does not tweak over time. Would I need to run 2 smaller shocks and add the lifting capability or do I need to run 2 shocks at the full lifting number. IE- 2 shocks at 250lb or 2 shocks at 125lb? Does that make sense?
Thanks for the help guys.
How do I figure what weight of shock I will need? I understand the collapsed and extended measurements, that's no problem but the lifting capability is in question.
I have roughly a 100lb lid plus a 125-150lb RTT. So call it 250lb to be safe. Now that is hinged on one side so the shocks wont be bench pressing 250lb. Do I cut that in half? I plan on using 2 shocks just so the lid does not tweak over time. Would I need to run 2 smaller shocks and add the lifting capability or do I need to run 2 shocks at the full lifting number. IE- 2 shocks at 250lb or 2 shocks at 125lb? Does that make sense?
Thanks for the help guys.
ntsqd
Heretic Car Camper
How fresh is your Trig and Strengths of Materials? :Wow1:
I'd model it as a beam with asymmetrical point supports (End [hinge] and partially cantilevered [struts]) with a distributed load. Say figure 18 here on pg. 12: http://www.awc.org/pdf/DA6-BeamFormulas.pdf. You're only interested in the values for R1 and R2, can ignore the rest of it. Bare in mind that the result will be for both struts and for the entire hinge.
Then it's a force triangle if the struts are mounted at any angle off of square. Trig if you know an angle and a distance, Pythagoras if you know two distances.
I'd model it as a beam with asymmetrical point supports (End [hinge] and partially cantilevered [struts]) with a distributed load. Say figure 18 here on pg. 12: http://www.awc.org/pdf/DA6-BeamFormulas.pdf. You're only interested in the values for R1 and R2, can ignore the rest of it. Bare in mind that the result will be for both struts and for the entire hinge.
Then it's a force triangle if the struts are mounted at any angle off of square. Trig if you know an angle and a distance, Pythagoras if you know two distances.
syke
Adventurer
That is what I was afraid of. :Wow1:
You see I went to public schools my entire life... graduated high school more because I had to not because I wanted to. So its safe to say Trigonometry is not my strong suit... you catch my drift? :sombrero:
With that being said... I will take a look at the website and try to figure it out. Worse case is I will buy a shock that is to strong and I am unable to close the lid.
Thanks again for the help.
go4aryd
Adventurer
It really depends on 1) mounting position closed, 2) shock strength, 3) position of shock with the lid open. You need assistance opening the door, but not so much it will not easily close, so there are two cases to consider.
Not all installs are the same. The back window of most SUVs has a strut, but it is to help hold the window open, not for assist in opening the window (though it typically does that also).
If your mounting position is nearly level with the lid, you won't gain much benefit compared to the rating (maybe 20%). For a good hint at the engineering principles, just look at the AT Chaser positioning of the gas spring with a box closed, and then opened. Notice the spring extends, but does not really rotate a bunch? Also, notice that the spring gets LONGER as the top rotates open.
BTW - There is actually an incorrect way to mount them, that will result in 0 assistance. That would be to mount them nearly parallel to the lid, mounted at the hinge and the midpoint of the lid edges. Mounted this way, the spring cannot expand to assist with the lid and really has no value.
I will be looking at this in detail this week. I need to figure out where to mount them in my M100 to get the most bang without hogging packing space near the tailgate.
Not all installs are the same. The back window of most SUVs has a strut, but it is to help hold the window open, not for assist in opening the window (though it typically does that also).
If your mounting position is nearly level with the lid, you won't gain much benefit compared to the rating (maybe 20%). For a good hint at the engineering principles, just look at the AT Chaser positioning of the gas spring with a box closed, and then opened. Notice the spring extends, but does not really rotate a bunch? Also, notice that the spring gets LONGER as the top rotates open.
BTW - There is actually an incorrect way to mount them, that will result in 0 assistance. That would be to mount them nearly parallel to the lid, mounted at the hinge and the midpoint of the lid edges. Mounted this way, the spring cannot expand to assist with the lid and really has no value.
I will be looking at this in detail this week. I need to figure out where to mount them in my M100 to get the most bang without hogging packing space near the tailgate.
Last edited:
HenryJ
Expedition Leader
I picked out my struts at the local auto parts recycler. $20 and I had what I needed. Most yards don't consider the gas lifts a big seller. I did my best to judge the weight and selected one with a comparable door. I chose to spread the load and use four to support the lid with tent. Two were just enough, but barely. A stiff wind may have closed the lid with the tent folded. With the four it is perfect. Two with stronger springs may have been an option, but this really did turn out well.
I chose to mount mine on the interior so that they are somewhat protected, however I did not want them taking up load space. Mine lay pretty flat when closed as the lower mounts are less than one inch down from the top lip of the box.
Boise is close. I am not far away. You might even see mine on the road. Holler if I can help.
I chose to mount mine on the interior so that they are somewhat protected, however I did not want them taking up load space. Mine lay pretty flat when closed as the lower mounts are less than one inch down from the top lip of the box.
Boise is close. I am not far away. You might even see mine on the road. Holler if I can help.
ntsqd
Heretic Car Camper
The Engineer's approach:That is what I was afraid of. :Wow1:
You see I went to public schools my entire life... graduated high school more because I had to not because I wanted to. So its safe to say Trigonometry is not my strong suit... you catch my drift? :sombrero:
With that being said... I will take a look at the website and try to figure it out. Worse case is I will buy a shock that is to strong and I am unable to close the lid.
Thanks again for the help.
Working through that formula using the closed lid dimensions will give you the vertical force needed at the lid mounting point to *just* fully support the lid.
If you adjust the l & a dimensions to where the mount would be with the lid fully open (ignore the vertical change in position and only work with the horizontal change in position), then it will give you the vertical force needed to keep the lid open *with no other loads*, like wind, involved.
The second half of the process is to measure the horizontal and vertical distances between the mounts (rather than the straight line distance) when open and when closed.
Then use "Similar Triangles" & "A^2 + B^2 = C^2"
where A is the horizontal distance (& the horizontal portion of the strut's force), B is the vertical distance (& vertical force component), and C is the strut's length (& rated force).
The practical approach:
Notch a piece of 2x4 to fit against the ends of the lid, bridging the length of the trailer, and align it with where you expect to put the upper gas spring mounts. Cut a piece of 2x4 that holds the lid fully open while fitting between the first 2x4 and a bathroom scale on the floor of the trailer.
That scale reading will be the minimum force needed to hold the lid fully open if the gas springs are installed such that they are vertical when the lid is fully open. Remember that the scale number represents the total of all of the gas springs used. Buy gas springs with a total force that is a little more force than your scale number to offset any wind, tilted parking spot, or other external influences.