Torsion-Free Sub-Frame

[Buckstopper]

It's me. I hope the article helps with the mystery around mounting a camper on these trucks. I have to say that the posts on this forum both inspired my build and made it work. Thanks to those who went before me for all the help.

Buckstopper.

 

[PacificNorthWestJeeper]

So I am in the process of an overland camper aluminum build on the back of an LMTV.
This thread is helpful but last updated in 2014...
Hoping for some ideas for a subframe for my camper to keep it from getting ripped apart while going down a trail.
Any Companys out there selling a kit or pieces?
I am a fairly good fabricator but looking for ideas, has to be something new in the last 6 years?

 

[mog]

Hoping for some ideas for a subframe for my camper to keep it from getting ripped apart while going down a trailer.
Any Companys out there selling a kit or pieces?
I am a fairly good fabricator but looking for ideas, has to be something new in the last 6 years?

You might try and contact Quade (pnwginger) here on the Expo Portal. He built an awesome subframe for his M1088A1 and at one time was offering complete subframes or plans for sale.
His build thread - Trucky McTruckface - Overland Adventure Truck
Photos on Instagram - overlandadventuretruck
Video on Facebook - Subframe in action... 4 point subframe design

 

[515]

Some nice practical testing of subframes FYI

 

[SkiFreak]

has to be something new in the last 6 years?

If I recollect correctly, the wheel has been around for quite some time now, with little or no changes to its design.
Basic mechanical engineering concepts don't change much either, but I will say, a subframe needs to be matched to the vehicle and terrain it will go on.
There is rarely ever a "one size fits all" solution when it comes to kinematic subframe systems.

 

[Victorian]

If I recollect correctly, the wheel has been around for quite some time now, with little or no changes to its design.
Basic mechanical engineering concepts don't change much either, but I will say, a subframe needs to be matched to the vehicle and terrain it will go on.
There is rarely ever a "one size fits all" solution when it comes to kinematic subframe systems.

100% agree. Not every design you see online is suitable for your truck . There is also a lot of info on very poorly designed subframes out there... I would recommend to go with a company that has a proven track record like overland adventure trucks in Olympia WA.

 

[PacificNorthWestJeeper]

You might try and contact Quade (pnwginger) here on the Expo Portal. He built an awesome subframe for his M1088A1 and at one time was offering complete subframes or plans for sale.
His build thread - Trucky McTruckface - Overland Adventure Truck
Photos on Instagram - overlandadventuretruck
Video on Facebook - Subframe in action... 4 point subframe design
View attachment 576220

I checked out the build and video's, VERY helpful, thank you for that!
So it looks like the rear pivot point lets the subframe pivot left and right while at the same time keeps it from falling forward.
Then the two pivot points about halfway up the subframe let the subframe pivot frontward and backwards.
Then the portion of the subframe furthest from the cab just floats?
Wonder what he used as a pivot mechanism, looks like more than just a bolt and bushings?
I thing that's how it works?

 

[mog]

Wonder what he used as a pivot mechanism, looks like more than just a bolt and bushings?
I thing that's how it works?

The layout is a 'standard' 4-point style.

I've seen it in person and it was a thing of beauty. I can not find my photos, but get in tough with Quade, he is a super nice guy and still in the PNW as far as I know.

 

[gringoinloscabos]

Bruce posted pictures recently on a thread here showing his air bag based pivot system and shocks to dampen up and down as well as side to side
movement.

The pictures are here:

http://www.expeditionportal.com/forum/showthread.php?t=5949&page=3

Where are these photos, please? I am in the process of re-fabbing my flatbed mount and want to make sure it is as awesome as possible.

 

[PacificNorthWestJeeper]

I am going to go with the 4 point style. I have been looking for a pivot point idea, ie 4,5,6 inch-ish solid steel bar and a bearing to slide for the bar as the pivot point. I even thought about using the center point from a big rig tandem axel setup. Making the actual subframe is easy, the pivot points of the subframe are the tough pieces to find/figurue out.... Any leads on the pieces or parts for this would be helpful, thank you

 

[Victorian]

If you just want pivot points that you can build your own sub-frame with, Globe Trekker sells just the pivots HERE towards the bottom of the page.

View attachment 801907

There are YouTube links on that page so you can get an idea as to their mounts/subframe in action.

Disclaimer - no relationship with Globe Trekker and no first-hand experience with their subframes/mounting systems

Certainly filling a niche.
But I'm puzzled how they can make these subframes and mounting points universal/non vehicle specific? Other than on mass produced expo trucks, everyone I have seen and worked on was custom due to vehicle specific specs. Some trucks (FusoFG for example) need a spring mounted system as the truck frame can not handle those type of point loads.
In one of the pictures I see some welded gussets on the frame rails. At first glance that looks amazingly simple. But I'm just going through some frame modifications myself and was under the impression that doing any type of welding on a frame needs to be done by a certified shop and paperwork that stays with the truck. Even then it's not recommended. Always best to use the pre drilled factory mounting points on a frame. Last thing you want is to weaken anything or introducing potential failure points.
Most Truck manufacturers are actually very specific where and how to mount accessories to the frame (see above with the Fuso)

I have also never seen side pivot mounts that move...What's the reason for that? With other manufacturers they look like pivots they are actually fixed and do not move!

 

[SkiFreak]

I am going to go with the 4 point style.

Hmmmmm.... if it is to go on a Fuso FG truck, I don't know if you have made the right decision.

This subject has been done to death over the years, so I will not go over all of the issues again, but I will reiterate that the FG is a very unique animal which does not lend itself to standard kinematic systems.
Basically, the frame rails are not flat and they are not what could be considered strong either. Point loads, as @Victorian has stated, can be a significant issue and welding directly to the chassis is definitely not recommended.

At the end of the day, it's your truck and you can do whatever the hell you want with it to meet your own requirements, but if history is anything to go by, spring mounts have been proven to be the best overall option for a kinematic subframe on these specific trucks.

 

[mog]

Hmmmmm.... if it is to go on a Fuso FG truck, I don't know if you have made the right decision.

From earlier in this thread.

 

[SkiFreak]

From earlier in this thread.

Only goes further in proving that my brain is getting old and does not remember things as it used to...
That said, I still believe that a spring mount system is a very viable, simple solution to most offroad camper builds.
As always... the design has to match the intended use, as there is rarely ever a "one size fits all" solution for these builds.

 

[mog]

That said, I still believe that a spring mount system is a very viable, simple solution to most offroad camper builds.
As always... the design has to match the intended use, as there is rarely ever a "one size fits all" solution for these builds.

I agree 100%. I took these at the Abenteuer Allrad show in Bad Kissingen, builder - 4wheel24
Click to enlarge/view


But more importantly for German construction, you must have adequate storage for your Bier und Sprudel


There is not a ton of detail in this Unicat video, but worth a watch, as is their whole video series. IMO