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Gas Shocks for Hatch Question

PostPosted: Thu May 03, 2007 9:52 am
by Classic Finn
Dear Friends

I took a lil roadtrip and found our gas shocks ... that are stainless steel
and the brackets for them..
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Now how do I go about finding the right "point" to install them on our hatch so I dont make a mistake on it ..

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Here is a pic of the assembly.

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Classic Finn

PostPosted: Thu May 03, 2007 11:04 am
by rbeemer

PostPosted: Thu May 03, 2007 12:13 pm
by Classic Finn
The seller said that I have to find the center point of the weight on the hatch :thinking: :thinking: :thinking:

I guess I dont get his thoughts on this.. :?

Classic Finn

PostPosted: Thu May 03, 2007 12:21 pm
by rbeemer
What is the kilo rating on them that there shocks. I think more important is where they can be put so the hatch will fully open and close

PostPosted: Thu May 03, 2007 12:34 pm
by Classic Finn
rbeemer wrote:What is the kilo rating on them that there shocks. I think more important is where they can be put so the hatch will fully open and close


The rating is 40 to 140kg.

Classic Finn

PostPosted: Thu May 03, 2007 12:48 pm
by rbeemer
Those are some heavy duty shocks 88- 308lbs each

There is a thread on the forum with a formula and directions for placing them. Search for Gas Struts. I do not think you have to worry about finding the centerpoint of weight because your hatch is not that heavy. If you can go look at truck canopies you can see how they position their struts/shocks for the rear door or look at rear door of a hatchback automobile.

PostPosted: Thu May 03, 2007 12:53 pm
by Classic Finn
rbeemer wrote:Those are some heavy duty shocks 88- 308lbs each

There is a thread on the forum with a formula and directions for placing them. Search for Gas Struts. I do not think you have to worry about finding the centerpoint of weight because your hatch is not that heavy. If you can go look at truck canopies you can see how they position their struts/shocks for the rear door or look at rear door of a hatchback automobile.


Rather be Safe than Sorry especially with little folks near ...

Classic Finn ;)

PostPosted: Fri May 04, 2007 2:08 am
by Classic Finn
Ok this is what I meant..for anyone else that this may help in the future. Now its figured out.

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Classic Finn

PostPosted: Sat May 05, 2007 7:32 am
by BrwBier
You could take a fish scale and lift the hatch to the hight you want it open to and when you find the point that the scale reads in the middle of the range of the shockes attach them at that point. Example, find the point where the scale reads 100 kg. when lifting with the scale. Does that sound reasonable? :thinking:
Brwbier

PostPosted: Sat May 05, 2007 8:20 am
by sdtripper2
Here are some sources for this subject:

Formulas and planning for Struts
Good explanation on sizing struts
and tools for calculating the size

http://www.easyliftsprings.com/contact/ ... urown.html
http://www.watertanks.com/calc.asp

Steve T's (sonetpro) formula for struts
http://tinyurl.com/zsxpw

Go here and scroll down to the strut area for more information:
http://tnttt.com/viewtopic.php?t=11210

PostPosted: Sat May 05, 2007 11:13 am
by angib
Heikki (and others),

In the post where you fond those drawings you will find the recommendation from Grant for where to put the ends of the gas struts - which is quite different from what I had drawn - it has the strut connected to the hatch fairly near the hinge, but connected to the body well away from the hinge. This has the result that gas strut pushes the hinge closed when the hatch is down - my way, the hinge is being pushed apart by the strut.

I decided not to remove those drawings as the thread would stop making sense if I did that - but maybe I should do so to avoid confusion.

I would draw you a new diagram using Grant's dimensions, but I'm away from home and don't have the time or software here.

Andrew