pivoting frames and mounting campers

Sitec

Adventurer
While pulling the living body I have apart for mods, widening etc I've been giving this 3 or 4 point mounting thought. The central 1 or 2 pivots that have to sit in the middle of the chassis between the two rails have to have decent allowable twist movement so the bush system (pictured a couple of posts up) is perfect IMO, as its greasable, allows free movement of the chassis to twist etc, and is very similar to the picture I had in my mind. What I am pondering though is the two outer chassis pivots that stop the body from falling to the left or right. These are usually roughly in the center of the body (one either side of the chassis) with the chassis internal pivots at the front and rear (on a 4 point system). On mine, I'm having the 2 fixed points near to the cab about a meter back from the front of the living body (purely so the walkthru stays roughly in line both sides. My thoughts are that even with the truck fully crossed up and the chassis twisted (100mm to 150mm chassis twist over 6 meters), there will be very little movement on the outer two mounts. With this in mind, I now plan to utilize two 50mm (2") holes (pictured) that are approx 1 meter behind the cab and roughly central in the chassis 'C' section. I'd have a pair of drop plates off the body (200mm x 16mm) plate?) which would have a machined boss the same size as the holes in the chassis. I'd then have a brass bush/boss that slid into the two holes and a large central bolt that goes through the center of the brass boss, with two large washers. This would be mirrored on the other rail, and would locate, clamp and hold the brass in place, form a rigid solid fix that still allow the small amount of twist flex on this front mount... Thoughts? It saves me drilling holes, utilizes an existing hole that'll act as a pivot...


515094
 

Darwin

Explorer
Just picked up my flatbed, it is a captive spring mount. You can see it and some videos of it in action on Instagram @mountainguildoverland.
 

Sitec

Adventurer
Hi brains trust. Going on from 4 point mounts. I've settled on my 2 fixed outer points being 'up front' as per my last post, with two central chassis pivots behind. One in the center of the body and one at the rear. To add to this system, I'm thinking of adding two rams on the outside of the chassis at the rear, which are linked to the body. When on decent roads, the taps are closed locking the rams, stopping body roll, but when off road, the taps are unlocked allowing the chassis to twist and flex without stressing the body. Thoughts? Sketch attached for reference.

525047
 

Coachgeo

Explorer
think you would just have to test that... could do that with just air bags too..... one bag or ram gets compressed as chassis is pushed toward the box.... that would send air/fluid to the opposite ram making it extend approx. same amount as the other side was compressed....... net result keeping the box level-ish.....

could also put a cab level (ride height) valve on it and use that to activate an air pump to maintain the air suspension . Read up on big rig air "cab" suspensions. Note... All of them have a shock AND an air bag on each side. Sometimes the air bag is built with the shock inside.... with out knowing this in advance some images/video's will confuse you.
 

billiebob

Well-known member
Your OBS PSD doesnt have a boxed frame under the cab.

Not sure when the change happened, but my 2011 does.
It creates a much more rigid platform for the cab to ride on.

From cab-forward it is a combination of boxed and open C
Cab-back, is all open C

Like so...



And 2017 and newer receive the new, fully boxed frame.



Whereas, the older nearly 100% open c-channel looks like so....

I'll take the early open C channel everytime.
 

Darwin

Explorer
I went with a captive spring mount in the front on my cab chassis 3500. Unfortunately I don't have any pictures of the mount and because the boxes are in the way now I am unable to get a good shot of the mounting system. If you want, you can check out some photos and videos of it being built on Instagram @mountainguildoverland

He did a really nice job building the bed and the mount.
 
Check out everlanders build on YouTube, he uses semi brake hydraulic pucks to secure body to frame when on tarmac and releases to drive off-road, I don’t know anyone else who uses this system, but this guy is a guru of gurus and Seems to really think through his systems before implementation
 

Coachgeo

Explorer
Check out everlanders build on YouTube, he uses semi brake hydraulic pucks to secure body to frame when on tarmac and releases to drive off-road, I don’t know anyone else who uses this system, but this guy is a guru of gurus and Seems to really think through his systems before implementation
been digging thru his videos for a good while to finaly find they info your refering too. so others do not have to dig as long

See at about 6'15" into video


at 11'42" into video is most of the detail. Vewy intewesting

Could this be utilized in a captured spring set up...... net result being captured spring with a locking mechanism essentially? Must be huge springs inside those cans for 6" of travel. Would just need a way to keep box from moving port or starboard while articulating. Many ways to do that and is common in captured spring setups.
 
Last edited:
Top