Build Status update Fuso FG140 4X4 2013.

drudru

Observer
The build is underway. I stripped the interior to install Hushmat (competitor of Dynamat), which will provide better insulation, bring the vibrations down and offer better sound proofing of the cab.
I covered most of the front, inside the doors metal and plastic panels, full floor, back wall and ceiling. I also covered the underside of the cab.

I have also started the construction of the sub frame. I am bugged on the exact design of the spring mounts. I am going for 6 anchor points. Each of a 4" travel. Building them similar to:
http://www.expeditionportal.com/forum/attachment.php?attachmentid=190735&d=1369497615
The problem I am facing is to select the proper size of the rod, and most importantly, the proper springs. Anyone has a suggestion?


Otherwise, so far, so good.

Link to images:
http://imgur.com/a/sDuGp
 

SkiFreak

Crazy Person
Each of a 4" travel.

Holy crap!
Are you building a subframe or a pretzel?
I designed my spring mounts to have 40mm of travel (1.6") but the springs should restrain this to a max of 30mm movement.
That may not seem like a lot, but with a 30mm separation between the subframe and the chassis there is about a 150mm difference from one side of the subframe to the other, and visually it looks like even more than that.
 

Czechsix

Watching you from a ridge
Regarding the hushmat - how much did you wind up using? I'm in the same boat, planning to do that within the next couple of months.
 

drudru

Observer
Holy crap!
Are you building a subframe or a pretzel?
I designed my spring mounts to have 40mm of travel (1.6") but the springs should restrain this to a max of 30mm movement.
That may not seem like a lot, but with a 30mm separation between the subframe and the chassis there is about a 150mm difference from one side of the subframe to the other, and visually it looks like even more than that.

I am looking for info on the springs mount design you used. Do you have a link or pics?
 

drudru

Observer
As with most things in my build, I have articles on my website that say how and why I did what I did.
The subframe related articles are here... part1, part2 and part3.

I found that you used 150mm long springs (which is about 6").
What I am trying to find out is what diameter, how many of them?, what Max load, Spring constant and max compressed size?
Those springs have really been giving me headaches.
 

SkiFreak

Crazy Person
One method is to do things as an engineer would..
You need to know, or estimate, what load will be on the subframe, then work out what effort will be placed on each mount point. If you have access to a 3D engineering CAD package (Solidworks, Rhino, Inventor etc.) then you can use this to do most of the hard work, as all of these programs have stress analysis capabilities. You should also take into consideration that there is a significant difference between static and dynamic loads.

Alternately, you can do as I did and make a "best guess", based on the the information you know. I have a general engineering background, so I would like to think that my best guess is not really a guess, but more a decision making process based on the information I have to work with and my past experience.

You definitely need to know approximately how much load will be on each spring. When you have determined that you can work out a suitable spring rate.
If this is all above your skill level, then you can contact a spring manufacturer and ask them for some assistance. The guys I worked with were very helpful, giving me options I had not even considered. Remember... that's what they do! They make springs.

The length, diameter and number of coils can all be worked out quite easily when you know how much load and range the springs need to have. Like with most custom builds, there is not really a "one size fits all" solution. What you will need will be dependent on how you plan on doing your build.
The spring rate is normally expressed as milimetres per kilogram, or inches per pound (I think), and this is all that really matters. You need a spring that has the correct spring rate and sufficient travel for your setup. Really, it's not more complicated than that.
 

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